draft-ietf-ipo-framework-03.txt   draft-ietf-ipo-framework-04.txt 
Bala Rajagopalan Bala Rajagopalan
Internet Draft Tellium, Inc. Internet Draft Tellium, Inc.
draft-ietf-ipo-framework-03.txt James Luciani draft-ietf-ipo-framework-04.txt James Luciani
Expires on: 7/13/2003 Consultant Expires on: 10/8/2003 Crescent Networks
Daniel Awduche Daniel Awduche
Isocore Isocore
IP over Optical Networks: A Framework IP over Optical Networks: A Framework
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
skipping to change at line 44 skipping to change at line 44
high-speed routers interconnected by optical core networks. The high-speed routers interconnected by optical core networks. The
architectural choices for the interaction between IP and optical architectural choices for the interaction between IP and optical
network layers, specifically, the routing and signaling aspects, are network layers, specifically, the routing and signaling aspects, are
maturing. At the same time, a consensus has emerged in the industry maturing. At the same time, a consensus has emerged in the industry
on utilizing IP-based protocols for the optical control plane. This on utilizing IP-based protocols for the optical control plane. This
document defines a framework for IP over Optical networks, document defines a framework for IP over Optical networks,
considering both the IP-based control plane for optical networks as considering both the IP-based control plane for optical networks as
well as IP-optical network interactions (together referred to as "IP well as IP-optical network interactions (together referred to as "IP
over optical networks"). over optical networks").
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
Table of Contents Table of Contents
----------------- -----------------
Abstract..............................................................1 Abstract..............................................................1
1. Introduction.......................................................3 1. Introduction.......................................................3
2. Terminology and Concepts...........................................4 2. Terminology and Concepts...........................................4
3. The Network Model..................................................8 3. The Network Model..................................................8
3.1 Network Interconnection.......................................8 3.1 Network Interconnection........................................8
3.2 Control Structure............................................10 3.2 Control Structure.............................................10
4. IP over Optical Service Models and Requirements...................12 4. IP over Optical Service Models and Requirements...................12
4.1 Domain Services Model........................................12 4.1 Domain Services Model.........................................12
4.2 Unified Service Model........................................13 4.2 Unified Service Model.........................................13
4.3 Which Service Model?.........................................14 4.3 Which Service Model?..........................................14
4.4 What are the Possible Services?...............................14 4.4 What are the Possible Services?................................14
5. IP transport over Optical Networks................................15 5. IP transport over Optical Networks................................15
5.1 Interconnection Models........................................15 5.1 Interconnection Models.........................................15
5.2 Routing Approaches............................................16 5.2 Routing Approaches.............................................16
5.3 Signaling-Related.............................................19 5.3 Signaling-Related..............................................19
5.4 End-to-End Protection Models.................................21 5.4 End-to-End Protection Models..................................21
6. IP-based Optical Control Plane Issues.............................23 6. IP-based Optical Control Plane Issues.............................23
6.1 Addressing...................................................23 6.1 Addressing....................................................23
6.2 Neighbor Discovery...........................................24 6.2 Neighbor Discovery............................................24
6.3 Topology Discovery...........................................25 6.3 Topology Discovery............................................25
6.4 Restoration Models...........................................26 6.4 Restoration Models............................................26
6.5 Route Computation............................................27 6.5 Route Computation.............................................27
6.6 Signaling Issues.............................................29 6.6 Signaling Issues..............................................29
6.7 Optical Internetworking......................................31 6.7 Optical Internetworking.......................................31
7. Other Issues......................................................32 7. Other Issues......................................................32
7.1 WDM and TDM in the Same Network.............................32 7.1 WDM and TDM in the Same Network..............................32
7.2 Wavelength Conversion.......................................32 7.2 Wavelength Conversion........................................32
7.3 Service Provider Peering Points.............................33 7.3 Service Provider Peering Points..............................33
7.4 Rate of Lightpath Set-Up....................................33 7.4 Rate of Lightpath Set-Up.....................................33
7.5 Distributed vs. Centralized Provisioning....................34 7.5 Distributed vs. Centralized Provisioning.....................34
7.6 Optical Networks with Additional Configurable Components....35 7.6 Optical Networks with Additional Configurable Components.....35
7.7 Optical Networks with Ltd Wavelength Conversion Capability..35 7.7 Optical Networks with Limited Wavelength Conversion Capability35
8. Evolution Path for IP over Optical Architecture..................35 8. Evolution Path for IP over Optical Architecture..................36
9. Security Considerations...........................................37 9. Security Considerations...........................................37
9.1 General security aspects......................................38 9.1 General Security Aspects.......................................38
9.2 Protocol Mechanisms...........................................39 9.2 Security Considerations for Protocol Mechanisms................39
10. Summary and Conclusions...........................................39 10. Summary and Conclusions..........................................40
11. References........................................................39 11. References.......................................................40
12. Acknowledgments...................................................40 12. Acknowledgments..................................................41
13. Contributors......................................................41 13. Contributors.....................................................42
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
1. Introduction 1. Introduction
Optical network technologies are evolving rapidly in terms of Optical network technologies are evolving rapidly in terms of
functions and capabilities. The increasing importance of optical functions and capabilities. The increasing importance of optical
networks is evidenced by the copious amount of attention focused on networks is evidenced by the copious amount of attention focused on
IP over optical networks and related photonic and electronic IP over optical networks and related photonic and electronic
interworking issues by all the major network service providers, interworking issues by all major network service providers,
telecommunications equipment vendors, and standards organizations. telecommunications equipment vendors, and standards organizations.
In this regard, the term "optical network" is used generically in In this regard, the term "optical network" is used generically in
practice to refer to both SONET/SDH-based transport networks, as practice to refer to both SONET/SDH-based transport networks, as
well as transparent all-optical networks. well as transparent all-optical networks.
It has been realized that optical networks must be survivable, It has been realized that optical networks must be survivable,
flexible, and controllable. There is, therefore, an ongoing trend to flexible, and controllable. There is, therefore, an ongoing trend to
introduce intelligence in the control plane of optical networks to introduce intelligence in the control plane of optical networks to
make them more versatile [1]. An essential attribute of intelligent make them more versatile [1]. An essential attribute of intelligent
optical networks is the capability to instantiate and route optical optical networks is the capability to instantiate and route optical
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layer connections in real-time or near real-time, and to provide layer connections in real-time or near real-time, and to provide
capabilities that enhance network survivability. Furthermore, there capabilities that enhance network survivability. Furthermore, there
is a need for multi-vendor optical network interoperability, when an is a need for multi-vendor optical network interoperability, when an
optical network may consist of interconnected vendor-specific optical network may consist of interconnected vendor-specific
optical sub-networks. optical sub-networks.
The optical network must also be versatile because some service The optical network must also be versatile because some service
providers may offer generic optical layer services that may not be providers may offer generic optical layer services that may not be
client-specific. It would therefore be necessary to have an optical client-specific. It would therefore be necessary to have an optical
network control plane that can handle such generic optical services. network control plane that can handle such generic optical services.
There is general consensus in the industry that the optical network There is general consensus in the industry that the optical network
control plane should utilize IP-based protocols for dynamic control plane should utilize IP-based protocols for dynamic
provisioning and restoration of lightpaths within and across optical provisioning and restoration of optical channels within and across
sub-networks. This is based on the practical view that signaling and optical sub-networks. This is based on the practical view that
routing mechanisms developed for IP traffic engineering applications signaling and routing mechanisms developed for IP traffic
could be re-used in optical networks. Nevertheless, the issues and engineering applications could be re-used in optical networks.
requirements that are specific to optical networking must be Nevertheless, the issues and requirements that are specific to
understood to suitably adopt and adapt the IP-based protocols. This optical networking must be understood to suitably adopt and adapt
is especially the case for restoration, and for routing and the IP-based protocols. This is especially the case for restoration,
signaling in all-optical networks. Also, there are different views and for routing and signaling in all-optical networks. Also, there
on the model for interaction between the optical network and client are different views on the model for interaction between the optical
networks, such as IP networks. Reasonable architectural alternatives network and client networks, such as IP networks. Reasonable
in this regard must be supported, with an understanding of their architectural alternatives in this regard must be supported, with an
relative merits. understanding of their relative merits.
Thus, there are two fundamental issues related to IP over optical Thus, there are two fundamental issues related to IP over optical
networks. The first is the adaptation and reuse of IP control plane networks. The first is the adaptation and reuse of IP control plane
protocols within the optical network control plane, irrespective of protocols within the optical network control plane, irrespective of
the types of digital clients that utilize the optical network. The the types of digital clients that utilize the optical network. The
second is the transport of IP traffic through an optical network second is the transport of IP traffic through an optical network
together with the control and coordination issues that arise together with the control and coordination issues that arise
therefrom. therefrom.
This document defines a framework for IP over optical networks This document defines a framework for IP over optical networks
covering the requirements and mechanisms for establishing an IP- covering the requirements and mechanisms for establishing an IP-
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
centric optical control plane, and the architectural aspects of IP centric optical control plane, and the architectural aspects of IP
transport over optical networks. In this regard, it is recognized transport over optical networks. In this regard, it is recognized
that the specific capabilities required for IP over optical networks that the specific capabilities required for IP over optical networks
would depend on the services expected at the IP-optical interface as would depend on the services expected at the IP-optical interface as
well as the optical sub-network interfaces. Depending on the well as the optical sub-network interfaces. Depending on the
specific operational requirements, a progression of capabilities is specific operational requirements, a progression of capabilities is
possible, reflecting increasingly sophisticated interactions at possible, reflecting increasingly sophisticated interactions at
these interfaces. This document therefore advocates the definition these interfaces. This document therefore advocates the definition
of "capability sets" that define the evolution of functionality at of "capability sets" that define the evolution of functionality at
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This document is organized as follows. In the next section, This document is organized as follows. In the next section,
terminology covering some basic concepts related to this framework terminology covering some basic concepts related to this framework
are described. The definitions are specific to this framework and are described. The definitions are specific to this framework and
may have other connotations elsewhere. In Section 3, the network may have other connotations elsewhere. In Section 3, the network
model pertinent to this framework is described. The service model model pertinent to this framework is described. The service model
and requirements for IP-optical, and multi-vendor optical and requirements for IP-optical, and multi-vendor optical
internetworking are described in Section 4. This section also internetworking are described in Section 4. This section also
considers some general requirements. Section 5 considers the considers some general requirements. Section 5 considers the
architectural models for IP-optical interworking, describing the architectural models for IP-optical interworking, describing the
pros and cons of each model. It should be noted that it is not the relative merits of each model. It should be noted that it is not the
intent of this document to promote any particular model over the intent of this document to promote any particular model over the
others. However, particular aspects of the models that may make one others. However, particular aspects of the models that may make one
approach more appropriate than another in certain circumstances are approach more appropriate than another in certain circumstances are
described. Section 6 describes IP-centric control plane mechanisms described. Section 6 describes IP-centric control plane mechanisms
for optical networks, covering signaling and routing issues in for optical networks, covering signaling and routing issues in
support of provisioning and restoration. Section 7 describes a support of provisioning and restoration. The approaches described in
number of specialized issues in relation to IP over optical Section 5 and 6 range from the relatively simple to the
networks. The approaches described in Section 5 and 6 range from sophisticated. Section 7 describes a number of specialized issues in
the relatively simple to the sophisticated. Section 8 describes a relation to IP over optical networks. Section 8 describes a
possible evolution path for IP over optical networking capabilities possible evolution path for IP over optical networking capabilities
in terms of increasingly sophisticated functionality that may be in terms of increasingly sophisticated functionality that may be
supported. Section 9 considers security issues pertinent to this supported as the need arises. Section 9 considers security issues
framework. Finally, the summary and conclusion are presented in pertinent to this framework. Finally, the summary and conclusion are
Section 10. presented in Section 10.
2. Terminology and Concepts 2. Terminology and Concepts
This section introduces terminology pertinent to this framework and This section introduces terminology pertinent to this framework and
some related concepts. The definitions are specific to this some related concepts. The definitions are specific to this
framework and may have other interpretations elsewhere. framework and may have other interpretations elsewhere.
WDM WDM
--- ---
Wavelength Division Multiplexing (WDM) is a technology that allows Wavelength Division Multiplexing (WDM) is a technology that allows
multiple optical signals operating at different wavelengths to be multiple optical signals operating at different wavelengths to be
multiplexed onto a single optical fiber and transported in parallel multiplexed onto a single optical fiber and transported in parallel
through the fiber. In general, each optical wavelength may carry through the fiber. In general, each optical wavelength may carry
digital client payloads at a different data rate (e.g., OC-3c, OC- digital client payloads at a different data rate (e.g., OC-3c, OC-
12c, OC- 48c, OC-192c, etc.) and in a different format (SONET, 12c, OC- 48c, OC-192c, etc.) and in a different format (SONET,
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
Ethernet, ATM, etc.) For example, there are many commercial WDM Ethernet, ATM, etc.) For example, there are many commercial WDM
networks in existence today that support a mix of SONET signals networks in existence today that support a mix of SONET signals
operating at OC-48c (approximately 2.5 Gbps) and OC-192 operating at OC-48c (approximately 2.5 Gbps) and OC-192
(approximately 10 Gbps) over a single optical fiber. An optical (approximately 10 Gbps) over a single optical fiber. An optical
system with WDM capability can achieve parallel transmission of system with WDM capability can achieve parallel transmission of
multiple wavelengths gracefully while maintaining high system multiple wavelengths gracefully while maintaining high system
performance and reliability. In the near future, commercial dense performance and reliability. In the near future, commercial dense
WDM systems are expected to concurrently carry more than 160 WDM systems are expected to concurrently carry more than 160
wavelengths at data rates of OC-192c and above, for a total of 1.6 wavelengths at data rates of OC-192c and above, for a total of 1.6
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Optical cross-connect (OXC) Optical cross-connect (OXC)
--------------------------- ---------------------------
An OXC is a space-division switch that can switch an optical data An OXC is a space-division switch that can switch an optical data
stream from an input port to a output port. Such a switch may stream from an input port to a output port. Such a switch may
utilize optical-electrical conversion at the input port and utilize optical-electrical conversion at the input port and
electrical-optical conversion at the output port, or it may be all- electrical-optical conversion at the output port, or it may be all-
optical. An OXC is assumed to have a control-plane processor that optical. An OXC is assumed to have a control-plane processor that
implements the signaling and routing protocols necessary for implements the signaling and routing protocols necessary for
computing and instantiating connectivity in the optical domain. computing and instantiating optical channel connectivity in the
optical domain.
Optical channel trail or Lightpath Optical channel trail or Lightpath
---------------------------------- ----------------------------------
An optical channel trail is a point-to-point optical layer An optical channel trail is a point-to-point optical layer
connection between two access points in an optical network. In this connection between two access points in an optical network. In this
document, the term "lightpath" is used interchangeably with optical document, the term "lightpath" is used interchangeably with optical
channel trail. channel trail.
Optical mesh sub-network Optical mesh sub-network
------------------------ ------------------------
An optical sub-network, as used in this framework, is a network of An optical sub-network, as used in this framework, is a network of
OXCs that supports end-to-end networking of optical channel trails OXCs that supports end-to-end networking of optical channel trails
providing functionality like routing, monitoring, grooming, and draft-ietf-ipo-framework-04.txt
draft-ietf-ipo-framework-03.txt
providing functionality like routing, monitoring, grooming, and
protection and restoration of optical channels. The interconnection protection and restoration of optical channels. The interconnection
of OXCs in this network can be based on a general mesh topology. of OXCs in this network can be based on a general mesh topology.
The following may underlie this network: The following sub-layers may be associated with this network:
(a) An optical multiplex section (OMS) layer network : The optical (a) An optical multiplex section (OMS) layer network : The optical
multiplex section layer provides transport for the optical multiplex section layer provides transport for the optical
channels. The information contained in this layer is a data channels. The information contained in this layer is a data
stream comprising a set of optical channels, which may have a stream comprising a set of optical channels, which may have a
defined aggregate bandwidth. defined aggregate bandwidth.
(b) An optical transmission section (OTS) layer network : This layer (b) An optical transmission section (OTS) layer network : This layer
provides functionality for transmission of optical signals provides functionality for transmission of optical signals
through different types of optical media. through different types of optical media.
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--------------------------------------------------- ---------------------------------------------------
A mesh optical network, as used in document, is a topologically A mesh optical network, as used in document, is a topologically
connected collection of optical sub-networks whose node degree may connected collection of optical sub-networks whose node degree may
exceed 2. Such an optical network is assumed to be under the purview exceed 2. Such an optical network is assumed to be under the purview
of a single administrative entity. It is also possible to conceive of a single administrative entity. It is also possible to conceive
of a large scale global mesh optical network consisting of the of a large scale global mesh optical network consisting of the
voluntary interconnection of autonomous optical networks, each of voluntary interconnection of autonomous optical networks, each of
which is owned and administered by an independent entity. In such an which is owned and administered by an independent entity. In such an
environment, abstraction can be used to hide the internal details of environment, abstraction can be used to hide the internal details of
each autonomous optical cloud from external clouds in the remainder each autonomous optical cloud from external clouds.
of the network.
Optical internetwork Optical internetwork
-------------------- --------------------
An optical internetwork is a mesh-connected collection of optical An optical internetwork is a mesh-connected collection of optical
networks. Each of these networks may be under a different networks. Each of these networks may be under a different
administration. administration.
Wavelength continuity property Wavelength continuity property
------------------------------ ------------------------------
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it is transported over the same wavelength end-to-end. Wavelength it is transported over the same wavelength end-to-end. Wavelength
continuity is required in optical networks with no wavelength continuity is required in optical networks with no wavelength
conversion feature. conversion feature.
Wavelength path Wavelength path
--------------- ---------------
A lightpath that satisfies the wavelength continuity property is A lightpath that satisfies the wavelength continuity property is
called a wavelength path. called a wavelength path.
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
Opaque vs. transparent optical networks Opaque vs. transparent optical networks
--------------------------------------- ---------------------------------------
A transparent optical network is an optical network in which optical A transparent optical network is an optical network in which optical
signals traverse from transmitter to receiver across intermediate signals traverse from transmitter to receiver across intermediate
nodes in the optical domain without OEO conversion. More generally, nodes in the optical domain without OEO conversion. More generally,
all intermediate nodes in a transparent optical network will pass all intermediate nodes in a transparent optical network will
optical signals without performing retiming and reshaping and thus transfer optical signals without performing retiming and reshaping
such nodes are unaware of the characteristics of the payload carried and thus such nodes are unaware of the characteristics of the
by the optical signals. payload carried by the optical signals.
Note that amplification of signals at transit nodes is Note that amplification of signals at transit nodes is
permitted in transparent optical networks (e.g. using Erbium Doped permitted in transparent optical networks (e.g. using Erbium Doped
Fiber Amplifiers EDFAs). Fiber Amplifiers EDFAs).
On the other hand, in opaque optical networks, transit nodes may On the other hand, in opaque optical networks, transit nodes may
manipulate optical signals traversing through them. An example of manipulate optical signals traversing through them. An example of
such manipulation would be OEO conversion which may involve 3R such manipulation would be OEO conversion which may involve 3R
operations (reshaping, retiming, regeneration/amplification). operations (reshaping, retiming, regeneration, and perhaps
amplification).
Trust domain Trust domain
------------ ------------
A trust domain is a network under a single technical administration A trust domain is a network under a single technical administration
in which adequate security measures are establish to prevent in which adequate security measures are established to prevent
unauthorized intrusion from outside the domain. Hence, most nodes in unauthorized intrusion from outside the domain. Hence, most nodes in
the domain are deemed to be secure or trusted in some fashion. the domain are deemed to be secure or trusted in some fashion.
Generally, the rule for "single" administrative control over a trust Generally, the rule for "single" administrative control over a trust
domain may be relaxed in practice if a set of administrative domain may be relaxed in practice if a set of administrative
entities agree to trust one another to form an enlarged entities agree to trust one another to form an enlarged
heterogeneous trust domain. However, to simplify the discussions in heterogeneous trust domain. However, to simplify the discussions in
this document, it will be assumed, without loss of generality, that this document, it will be assumed, without loss of generality, that
the term trust domain applies to a single administrative entity with the term trust domain applies to a single administrative entity with
appropriate security policies. It should be noted that within a appropriate security policies. It should be noted that within a
trust domain, any subverted node can send control messages which can trust domain, any subverted node can send control messages which can
compromise the entire network. compromise the entire network.
Flow Flow
---- ----
For purposes of this document, the term flow will be used to For purposes of this document, the term flow will be used to
signify the smallest non-separable stream of data, from the point of signify the smallest non-separable stream of data, from the point of
view of endpoint or termination point (source or destination node). view of an endpoint or termination point (source or destination
The reader should note that the term flow is heavily overloaded in node). The reader should note that the term flow is heavily
contemporary networking literature. Therefore, within the context of overloaded in contemporary networking literature. Therefore, within
this document, it may be convenient to consider a wavelength as a the context of this document, it may be convenient to consider a
flow under certain circumstances. However, if there wavelength as a flow under certain circumstances. However, if there
is a method to partition the bandwidth of the wavelength, then each is a method to partition the bandwidth of the wavelength, then each
partition may be considered a flow, for example by using time partition may be considered a flow, for example using time division
division multiplexing (RDM) to quantize time into time slots, it may multiplexing (TDM) to quantize time into time slots, it may be
be feasible to consider each quanta of time within a given feasible to consider each quanta of time within a given wavelength
wavelength as a flow. as a flow.
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
Traffic Trunk Traffic Trunk
------------- -------------
A traffic trunk is an abstraction of traffic flow that follows the A traffic trunk is an abstraction of traffic flow traversing the
same path between two access points which allows some same path between two access points which allows some
characteristics and attributes of the traffic to be parameterized. characteristics and attributes of the traffic to be parameterized.
3. The Network Model 3. The Network Model
3.1 Network Interconnection 3.1 Network Interconnection
The network model considered in this memo consists of IP routers The network model considered in this memo consists of IP routers
attached to an optical core internetwork, and connected to their attached to an optical core internetwork, and connected to their
peers over dynamically established switched optical channels. The peers over dynamically established switched optical channels. The
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The switching function in an OXC is controlled by appropriately The switching function in an OXC is controlled by appropriately
configuring the cross-connect fabric. Conceptually, this may be configuring the cross-connect fabric. Conceptually, this may be
viewed as setting up a cross-connect table whose entries are of the viewed as setting up a cross-connect table whose entries are of the
form <input port i, output port j>, indicating that the data stream form <input port i, output port j>, indicating that the data stream
entering input port i will be switched to output port j. In the entering input port i will be switched to output port j. In the
context of a wavelength selective cross-connect (generally referred context of a wavelength selective cross-connect (generally referred
to as a WXC), the cross-connect tables may also indicate the input to as a WXC), the cross-connect tables may also indicate the input
and output wavelengths along with the input and output ports. A and output wavelengths along with the input and output ports. A
lightpath from an ingress port in an OXC to an egress port in a lightpath from an ingress port in an OXC to an egress port in a
remote OXC is established by setting up suitable cross-connects in remote OXC is established by setting up suitable cross-connects in
the ingress, the egress and a set of intermediate OXCs such that a draft-ietf-ipo-framework-04.txt
draft-ietf-ipo-framework-03.txt
the ingress, the egress and a set of intermediate OXCs such that a
continuous physical path exists from the ingress to the egress port. continuous physical path exists from the ingress to the egress port.
Optical paths tend to be bi-directional, i.e., the return path from Optical paths tend to be bi-directional, i.e., the return path from
the egress port to the ingress port is typically routed along the the egress port to the ingress port is typically routed along the
same set of intermediate ports as the forward path, but this may not same set of intermediate ports as the forward path, but this may not
be the case under all circumstances. be the case under all circumstances.
Optical Network Optical Network
+----------------------------------------+ +----------------------------------------+
| | | |
| Optical Subnetwork | | Optical Subnetwork |
+--------------+ | +------------------------------------+ | +--------------+ | +------------------------------------+ |
| | | | +-----+ +-----+ +-----+ | | | | | | +-----+ +-----+ +-----+ | |
| IP | | | | | | | | | | | | IP | | | | | | | | | | |
| Network +--UNI--+--+ OXC +------+ OXC +------+ OXC + | | | Network +--UNI--+--+ OXC +------+ OXC +------+ OXC + | |
| | | | | | | | | | | | | | | | | | | | | | | |
+--------------+ | | +--+--+ +--+--+ +--+--+ | | +--------------+ | | +--+--+ +--+--+ +--+--+ | |
| +-----|------------|------------|----+ | | +-----|------------|------------|----+ |
| | | | | | | | | | | INNI INNI INNI | +--------------+ | | | | | | | | +-----+------+ | +-------+----+ | | IP +--UNI--| +-----+ | | |
| INNI INNI INNI |
+--------------+ | | | | |
| | | +-----+------+ | +-------+----+ |
| IP +--UNI--| +-----+ | | |
| Network | | | Optical | | Optical | | | Network | | | Optical | | Optical | |
| | | | Subnetwork +---INNI---+ Subnetwork | | | | | | Subnetwork +---INNI---+ Subnetwork | |
+--------------+ | | | | | | +--------------+ | | | | | |
| +------+-----+ +------+-----+ | | +------+-----+ +------+-----+ |
| | | | | | | |
+--------+-----------------------+-------+ +--------+-----------------------+-------+
| | | |
ENNI ENNI ENNI ENNI
| | | |
+--------+-----------------------+-------+ +--------+-----------------------+-------+
| | | |
| Optical Network | | Optical Network |
| | | |
+--------+-----------------------+-------+ +--------+-----------------------+-------+ | |
| |
UNI UNI UNI UNI
| | | |
+------+-------+ +------+-----+ +------+-------+ +------+-----+
| | | | | | | |
| Other Client | |Other Client| | Other Client | |Other Client|
| Network | | Network | | Network | | Network |
| (e.g., ATM) | | | | (e.g., ATM) | | |
+--------------+ +------------+ +--------------+ +------------+
Figure 1: Optical Internetwork Model Figure 1: Optical Internetwork Model
Multiple data streams output from an OXC may be multiplexed onto an Multiple data streams output from an OXC may be multiplexed onto an
optical link using WDM technology. The WDM functionality may exist optical link using WDM technology. The WDM functionality may exist
outside of the OXC, and be transparent to the OXC. Or, this function outside of the OXC, and be transparent to the OXC. Or, this function
may be built into the OXC. In the later case, the cross-connect may be built into the OXC. In the later case, the cross-connect
table (conceptually) consists of pairs of the form, <{input port draft-ietf-ipo-framework-04.txt
draft-ietf-ipo-framework-03.txt
table (conceptually) consists of pairs of the form, <{input port
i, Lambda(j)}, {output port k, Lambda(l)}>. This indicates that the i, Lambda(j)}, {output port k, Lambda(l)}>. This indicates that the
data stream received on wavelength Lambda(j) over input port i is data stream received on wavelength Lambda(j) over input port i is
switched to output port k on Lambda(l). Automated establishment of switched to output port k on Lambda(l). Automated establishment of
lightpaths involves setting up the cross-connect table entries in lightpaths involves setting up the cross-connect table entries in
the appropriate OXCs in a coordinated manner such that the desired the appropriate OXCs in a coordinated manner such that the desired
physical path is realized. physical path is realized.
Under this network model, a switched lightpath must be established Under this network model, a switched lightpath must be established
between a pair of IP routers before they can communicate. This between a pair of IP routers before they can communicate. This
lightpath might traverse multiple optical networks and be subject to lightpath might traverse multiple optical networks and be subject to
skipping to change at line 501 skipping to change at line 496
paths from one IP endpoint to another over an optical network. paths from one IP endpoint to another over an optical network.
3.2 Control Structure 3.2 Control Structure
There are three logical control interfaces identified in Figure 1. There are three logical control interfaces identified in Figure 1.
These are the client-optical internetwork interface, the internal These are the client-optical internetwork interface, the internal
node-to-node interface within an optical network (between OXCs in node-to-node interface within an optical network (between OXCs in
different sub-networks), and the external node-to-node interface different sub-networks), and the external node-to-node interface
between nodes in different optical networks. These interfaces are between nodes in different optical networks. These interfaces are
also referred to as the User-Network Interface (UNI), the internal also referred to as the User-Network Interface (UNI), the internal
NNI (INNI), and the external NNI, respectively. NNI (INNI), and the external NNI (ENNI), respectively.
The distinction between these interfaces arises out of the type and The distinction between these interfaces arises out of the type and
amount of control information flow across them. The client-optical amount of control information flow across them. The client-optical
internetwork interface (UNI) represents a service boundary between internetwork interface (UNI) represents a service boundary between
the client and optical networks. The client and server are the client (e.g. IP router) and the optical network. The client and
essentially two different roles: the client role requests a service server (optical network) are essentially two different roles: the
connection from a server; the server role establishes the connection client role requests a service connection from a server; the server
to fulfill the service request -- provided all relevant admission role establishes the connection to fulfill the service request --
control conditions are satisfied. provided all relevant admission control conditions are satisfied.
Thus, the control flow across the client-optical internetwork Thus, the control flow across the client-optical internetwork
interface is dependent on the set of services defined across it interface is dependent on the set of services defined across it
and the manner in which the services may be accessed. The service and the manner in which the services may be accessed. The service
models are described in Section 4. The NNIs represent vendor- models are described in Section 4. The NNIs represent vendor-
independent standardized control flow between nodes. The distinction independent standardized control flow between nodes. The distinction
between the INNI and the ENNI is that the former is an interface between the INNI and the ENNI is that the former is an interface
within a given network under a single technical administration, within a given network under a single technical administration,
while the later indicates an interface at the administrative while the later indicates an interface at the administrative
boundary between networks. The INNI and ENNI may thus differ in the boundary between networks. The INNI and ENNI may thus differ in the
policies that restrict control flow between nodes. policies that restrict control flow between nodes.
draft-ietf-ipo-framework-04.txt
Security, scalability, stability, and information hiding are Security, scalability, stability, and information hiding are
important considerations in the specification of the ENNI. It is important considerations in the specification of the ENNI. It is
draft-ietf-ipo-framework-03.txt
possible in principle to harmonize the control flow across the UNI possible in principle to harmonize the control flow across the UNI
and the NNI and eliminate the distinction between them. On the other and the NNI and eliminate the distinction between them. On the other
hand, it may be required to minimize control flow information, hand, it may be required to minimize flow of control information,
especially routing-related information, over the UNI; and even over especially routing-related information, over the UNI; and even over
the ENNI. In this case, UNI and NNIs may look different in some the ENNI. In this case, UNI and NNIs may look different in some
respects. In this document, these interfaces are treated as respects. In this document, these interfaces are treated as
distinct. distinct.
The client-optical internetwork interface can be categorized as The client-optical internetwork interface can be categorized as
public or private depending upon context and service models. Routing public or private depending upon context and service models. Routing
information (ie, topology state information) can be exchanged across information (i.e., topology state information) can be exchanged
a private client-optical internetwork interface. On the other hand, across a private client-optical internetwork interface. On the other
such information is not exchanged across a public client-optical hand, such information is not exchanged across a public client-
internetwork interface, or such information may be exchanged with optical internetwork interface, or such information may be exchanged
very explicit restrictions (including, for example abstraction, with very explicit restrictions (including, for example abstraction,
filtration, etc). Thus, different relationships (e.g., peer or over- filtration, etc). Thus, different relationships (e.g., peer or over-
lay, Section 5) may occur across private and public logical lay, Section 5) may occur across private and public logical
interfaces. interfaces.
The physical control structure used to realize these logical The physical control structure used to realize these logical
interfaces may vary. For instance, for the client-optical interfaces may vary. For instance, for the client-optical
internetwork interface, some of the possibilities are: internetwork interface, some of the possibilities are:
1. Direct interface: An in-band or out-of-band IP control channel 1. Direct interface: An in-band or out-of-band IP control channel
(IPCC) may be implemented between an edge router and each OXC (IPCC) may be implemented between an edge router and each OXC to which it is connected. This control channel is used for
to which it is connected. This control channel is used for
exchanging signaling and routing messages between the router and exchanging signaling and routing messages between the router and
the OXC. With a direct interface, the edge router and the OXC it the OXC. With a direct interface, the edge router and the OXC it
connects to are peers with respect to the control plane. This connects to are peers with respect to the control plane. This
situation is shown in Figure 2. The type of routing and signaling situation is shown in Figure 2. The type of routing and signaling
information exchanged across the direct interface may vary information exchanged across the direct interface may vary
depending on the service definition. This issue is addressed in depending on the service definition. This issue is addressed in
the next section. Some choices for the routing protocol are OSPF the next section. Some choices for the routing protocol are OSPF
or ISIS (with traffic engineering extensions and additional or ISIS (with traffic engineering extensions and additional
enhancements to deal with the peculiar characteristics of optical enhancements to deal with the peculiar characteristics of optical
networks) or BGP, or some other protocol. Other directory-based networks) or BGP, or some other protocol. Other directory-based
skipping to change at line 579 skipping to change at line 573
implemented between the client and a device in the optical network implemented between the client and a device in the optical network
to signal service requests and responses. For instance, a to signal service requests and responses. For instance, a
management system or a server in the optical network may receive management system or a server in the optical network may receive
service requests from clients. Similarly, out-of-band signaling service requests from clients. Similarly, out-of-band signaling
may be used between management systems in client and optical may be used between management systems in client and optical
networks to signal service requests. In these cases, there is no networks to signal service requests. In these cases, there is no
direct control interaction between clients and respective direct control interaction between clients and respective
OXCs. One reason to have an indirect interface would be that the OXCs. One reason to have an indirect interface would be that the
OXCs and/or clients do not support a direct signaling interface. OXCs and/or clients do not support a direct signaling interface.
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
+-----------------------------+ +-----------------------------+ +-----------------------------+ +-----------------------------+
| | | | | | | |
| +---------+ +---------+ | | +---------+ +---------+ | | +---------+ +---------+ | | +---------+ +---------+ |
| | | | | | | | | | | | | | | | | | | | | | | |
| | Routing | |Signaling| | | | Routing | |Signaling| | | | Routing | |Signaling| | | | Routing | |Signaling| |
| | Protocol| |Protocol | | | | Protocol| |Protocol | | | | Protocol| |Protocol | | | | Protocol| |Protocol | |
| | | | | | | | | | | | | | | | | | | | | | | |
| +-----+---+ +---+-----+ | | +-----+---+ +---+-----+ | | +-----+---+ +---+-----+ | | +-----+---+ +---+-----+ |
| | | | | | | | | | | | | | | |
skipping to change at line 622 skipping to change at line 616
In this section, the service models and requirements at the UNI and In this section, the service models and requirements at the UNI and
the NNIs are considered. Two general models have emerged for the the NNIs are considered. Two general models have emerged for the
services at the UNI (which can also be applied at the NNIs). These services at the UNI (which can also be applied at the NNIs). These
models are as follows. models are as follows.
4.1 Domain Services Model 4.1 Domain Services Model
Under the domain services model, the optical network primarily Under the domain services model, the optical network primarily
offers high bandwidth connectivity in the form of lightpaths. offers high bandwidth connectivity in the form of lightpaths.
Standardized signaling across the UNI (Figure 1) is used to invoke Standardized signaling across the UNI (Figure 1) is used to invoke
the following the following services:
services:
1. Lightpath creation: This service allows a lightpath with the 1. Lightpath creation: This service allows a lightpath with the
specified attributes to be created between a pair of termination specified attributes to be created between a pair of termination
points in the optical network. Lightpath creation may be subject points in the optical network. Lightpath creation may be subject
to network-defined policies (e.g., connectivity restrictions) and to network-defined policies (e.g., connectivity restrictions) and
security procedures. security procedures.
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2. Lightpath deletion: This service allows an existing lightpath to 2. Lightpath deletion: This service allows an existing lightpath to
be deleted. be deleted.
3. Lightpath modification: This service allows certain parameters of 3. Lightpath modification: This service allows certain parameters of
the lightpath to be modified. the lightpath to be modified.
4. Lightpath status enquiry: This service allows the status of 4. Lightpath status enquiry: This service allows the status of
certain parameters of the lightpath (referenced by its ID) to be certain parameters of the lightpath (referenced by its ID) to be
queried by the router that created the lightpath. queried by the router that created the lightpath.
skipping to change at line 676 skipping to change at line 669
is discussed in Section 5. is discussed in Section 5.
4.2 Unified Service Model 4.2 Unified Service Model
Under this model, the IP and optical networks are treated together Under this model, the IP and optical networks are treated together
as a single integrated network from a control plane point of view. as a single integrated network from a control plane point of view.
In this regard, the OXCs are treated just like any other router as In this regard, the OXCs are treated just like any other router as
far as the control plane is considered. Thus, in principle, there is far as the control plane is considered. Thus, in principle, there is
no distinction between the UNI, NNIs and any other router-to-router no distinction between the UNI, NNIs and any other router-to-router
interface from a routing and signaling point of view. It is assumed interface from a routing and signaling point of view. It is assumed
that this control plane is MPLS-based, as described in [1]. The that this control plane is IP-based, for example leveraging the
unified service model has so far been discussed only in the context traffic engineering extensions for MPLS or GMPLS, as described in
of a single administrative domain. A unified control plane is [1]. The unified service model has so far been discussed only in the
possible even when there are administrative boundaries within an context of a single administrative domain. A unified control plane
is possible even when there are administrative boundaries within an
optical internetwork, but some of the integrated routing optical internetwork, but some of the integrated routing
capabilities may not be practically attractive or even feasible in capabilities may not be practically attractive or even feasible in
this case (see Section 5). this case (see Section 5).
Under the unified service model and within the context of an MPLS or draft-ietf-ipo-framework-04.txt
GMPLS network, optical network services are obtained implicitly
draft-ietf-ipo-framework-03.txt
during end-to-end GMPLS signaling. Specifically, an edge router can Under the unified service model and within the context of a GMPLS
create a lightpath with specified attributes, or delete and modify network, optical network services are obtained implicitly during
end-to-end GMPLS signaling. Specifically, an edge router can create
a lightpath with specified attributes, or delete and modify
lightpaths as it creates GMPLS label-switched paths (LSPs). In this lightpaths as it creates GMPLS label-switched paths (LSPs). In this
regard, the services obtained from the optical network are similar regard, the services obtained from the optical network are similar
to the domain services model. These services, however, may be to the domain services model. These services, however, may be
invoked in a more seamless manner as compared to the domain services invoked in a more seamless manner as compared to the domain services
model. For instance, when routers are attached to a single optical model. For instance, when routers are attached to a single optical
network (i.e., there are no ENNIs), a remote router could compute an network (i.e., there are no ENNIs), a remote router could compute an
end-to-end path across the optical internetwork. It can then end-to-end path across the optical internetwork. It can then
establish an LSP across the optical internetwork. But the edge establish an LSP across the optical internetwork. But the edge
routers must still recognize that an LSP across the optical routers must still recognize that an LSP across the optical
internetwork is a lightpath, or a conduit for multiple LSPs. internetwork is a lightpath, or a conduit for multiple packet-based
LSPs.
The concept of "forwarding adjacency" can be used to specify virtual The concept of "forwarding adjacency" can be used to specify virtual
links across optical internetworks in routing protocols such as OSPF links across optical internetworks in routing protocols such as OSPF
[3]. In essence, once a lightpath is established across an optical [3]. In essence, once a lightpath is established across an optical
internetwork between two edge routers, the lightpath can be internetwork between two edge routers, the lightpath can be
advertised as a forwarding adjacency (a virtual link) between these advertised as a forwarding adjacency (a virtual link) between these
routers. Thus, from a data plane point of view, the lightpaths routers. Thus, from a data plane point of view, the lightpaths
result in a virtual overlay between edge routers. The decisions as result in a virtual overlay between edge routers. The decisions as
to when to create such lightpaths, and the bandwidth management for to when to create such lightpaths, and the bandwidth management for
these lightpaths is identical in both the domain services model and these lightpaths is identical in both the domain services model and
the unified service model. The routing and signaling models for the unified service model. The routing and signaling models for
unified services is described in Sections 5 and 6. unified services is described in Sections 5 and 6.
4.3 Which Service Model? 4.3 Which Service Model?
The pros and cons of the above service models can be debated at The relative merits of the above service models can be debated at
length, but the approach recommended in this framework is to define length, but the approach recommended in this framework is to define
routing and signaling mechanisms in support of both models. As noted routing and signaling mechanisms in support of both models. As noted
above, signaling for service requests can be unified to cover both above, signaling for service requests can be unified to cover both
models. The developments in GMPLS signaling [4] for the unified models. The developments in GMPLS signaling [4] for the unified
service model and its adoption for UNI signaling [5, 6] under the service model and its adoption for UNI signaling [5, 6] under the
domain services model essentially supports this view. The domain services model essentially supports this view. The
significant difference between the service models, however, is in significant difference between the service models, however, is in
routing protocols, as described in Sections 5 and 6. routing protocols, as described in Sections 5 and 6.
4.4 What are the Possible Services? 4.4 What are the Possible Services?
Specialized services may be built atop the point-to-point Specialized services may be built atop the point-to-point
connectivity service offered by the optical network. For example, connectivity service offered by the optical network. For example,
optical virtual private networks and bandwidth on demand are some of optical virtual private networks and bandwidth on demand are some of
the services that can be envisioned. the services that can be envisioned.
4.4.1 Optical Virtual Private Networks (OVPNs) 4.4.1 Optical Virtual Private Networks (OVPNs)
Given that the data plane between IP routers over an optical network Given that the data plane links between IP routers over an optical
amounts to a virtual topology which is an overlay over the optical network amounts to a virtual topology which is an overlay over the
network, it is easy to envision a virtual private network of fiber optic network, it is easy to envision a virtual private
lightpaths that interconnect routers (or any other set of clients) network of lightpaths that interconnect routers (or any other set of
belonging to a single entity or a group of related entities across a draft-ietf-ipo-framework-04.txt
public optical network. Indeed, in the case where the optical
network provides connectivity for multiple sets of external client
draft-ietf-ipo-framework-03.txt
networks, there has to be a way to enforce routing policies that clients) belonging to a single entity or a group of related entities
ensure routing separation between different sets of client networks across a public optical network. Indeed, in the case where the
(i.e., VPN service). optical network provides connectivity for multiple sets of external
client networks, there has to be a way to enforce routing policies
that ensure routing separation between different sets of client
networks (i.e., VPN service).
5. IP transport over Optical Networks 5. IP transport over Optical Networks
To examine the architectural alternatives for IP over optical To examine the architectural alternatives for IP over optical
networks, it is important to distinguish between the data and networks, it is important to distinguish between the data and
control planes over the UNI. The optical network provides a service control planes. The optical network provides a service to external
to external entities in the form of fixed bandwidth transport pipes entities in the form of fixed bandwidth transport pipes (optical
(optical paths). IP routers at the edge of the optical networks must paths). IP routers at the edge of the optical networks must
necessarily have such paths established between them before necessarily have such paths established between them before
communication at the IP layer can commence. Thus, the IP data plane communication at the IP layer can commence. Thus, the IP data plane
over optical networks is realized over a virtual topology of optical over optical networks is realized over a virtual topology of optical
paths. On the other hand, IP routers and OXCs can have a peer paths. On the other hand, IP routers and OXCs can have a peer
relation with respect to the control plane, especially for routing relation with respect to the control plane, especially for routing
protocols that permit the dynamic discovery of IP endpoints attached protocols that permit the dynamic discovery of IP endpoints attached
to the optical network. to the optical network.
The IP over optical network architecture is defined essentially by The IP over optical network architecture is defined essentially by
the organization of the control plane. The assumption in this the organization of the control plane. The assumption in this
skipping to change at line 777 skipping to change at line 772
tightly coupled. This coupling determines the following tightly coupled. This coupling determines the following
characteristics: characteristics:
o The details of the topology and routing information advertised by o The details of the topology and routing information advertised by
the optical network across the client interface; the optical network across the client interface;
o The level of control that IP routers can exercise in selecting o The level of control that IP routers can exercise in selecting
explicit paths for connections across the optical network; explicit paths for connections across the optical network;
o Policies regarding the dynamic provisioning of optical paths o Policies regarding the dynamic provisioning of optical paths
between routers. These include access control, accounting and between routers. These include access control, accounting, and
security issues. security issues.
The following interconnection models are then possible: The following interconnection models are then possible:
5.1 Interconnection Models 5.1 Interconnection Models
5.1.1 The Peer Model 5.1.1 The Peer Model
Under the peer model, the IP control plane acts as a peer of the Under the peer model, the IP control plane acts as a peer of the
optical transport network control. This implies that a single optical transport network control plane. This implies that a single
instance of the control plane is deployed over the IP and optical instance of the control plane is deployed over the IP and optical
domains. When there is a single optical network involved and the IP domains. When there is a single optical network involved and the IP
and optical domains belong to the same entity, then a common IGP and optical domains belong to the same entity, then a common IGP
such as OSPF or IS-IS, with appropriate extensions, can be used to such as OSPF or IS-IS, with appropriate extensions, can be used to
draft-ietf-ipo-framework-04.txt
distribute topology information [7] over the integrated IP-optical distribute topology information [7] over the integrated IP-optical
network. In the case of OSPF, opaque LSAs can be used to advertise network. In the case of OSPF, opaque LSAs can be used to advertise
topology state information. In the case of IS-IS, extended TLVs will topology state information. In the case of IS-IS, extended TLVs will
draft-ietf-ipo-framework-03.txt
have to be defined to propagate topology state information. Many of have to be defined to propagate topology state information. Many of
these extensions are occurring within the context of GMPLS. these extensions are occurring within the context of GMPLS.
When an optical internetwork with multiple optical networks is When an optical internetwork with multiple optical networks is
involved (e.g., spanning different administrative domains), a involved (e.g., spanning different administrative domains), a
single instance of an intra-domain routing protocol is not single instance of an intra-domain routing protocol is not
attractive or even realistic. In this case, inter-domain routing and attractive or even realistic. In this case, inter-domain routing and
signaling protocols are needed. In either case, a tacit assumption signaling protocols are needed. In either case, a tacit assumption
is that a common addressing scheme will be used for the optical and is that a common addressing scheme will be used for the optical and
IP networks. A common address space can be trivially realized by IP networks. A common address space can be trivially realized by
skipping to change at line 847 skipping to change at line 842
are described below. are described below.
5.2 Routing Approaches 5.2 Routing Approaches
5.2.1 Integrated Routing 5.2.1 Integrated Routing
This routing approach supports the peer model within a single This routing approach supports the peer model within a single
administrative domain. Under this approach, the IP and optical administrative domain. Under this approach, the IP and optical
networks are assumed to run the same instance of an IP routing networks are assumed to run the same instance of an IP routing
protocol, e.g., OSPF with suitable "optical" extensions. These protocol, e.g., OSPF with suitable "optical" extensions. These
draft-ietf-ipo-framework-04.txt
extensions must capture optical link parameters, and any constraints extensions must capture optical link parameters, and any constraints
that are specific to optical networks. The topology and link state that are specific to optical networks. The topology and link state
information maintained by all nodes (OXCs and routers) may be information maintained by all nodes (OXCs and routers) may be
draft-ietf-ipo-framework-03.txt
identical, but not necessarily. This approach permits a router to identical, but not necessarily. This approach permits a router to
compute an end-to-end path to another router across the optical compute an end-to-end path to another router across the optical
network. Suppose the path computation is triggered by the need to network. Suppose the path computation is triggered by the need to
route a label switched path (LSP) in a GMPLS environment. Such an route a label switched path (LSP) in a GMPLS environment. Such an
LSP can be established using GMPLS signaling, e.g., RSVP-TE or CR- LSP can be established using GMPLS signaling, e.g., RSVP-TE or CR-
LDP with appropriate extensions. In this case, the signaling LDP with appropriate extensions. In this case, the signaling
protocol will establish a ightpath between two edge routers. This protocol will establish a lightpath between two edge routers. This
lightpath is in essence a tunnel across the optical network, and may lightpath is in essence a tunnel across the optical network, and may
have capacity much larger than the bandwidth required to support the have capacity much larger than the bandwidth required to support the
first LSP. Thus, it is essential that other routers in the network first LSP. Thus, it is essential that other routers in the network
realize the availability of excess capacity within the lightpath so realize the availability of excess capacity within the lightpath so
that subsequent LSPs between the routers can use it rather that subsequent LSPs between the routers can use it rather than
instantiating a new lightpath. The lightpath may therefore be instantiating a new lightpath. The lightpath may therefore be
advertised as a virtual link in the topology as a means to address advertised as a virtual link in the topology as a means to address
this issue. this issue.
The notion of "forwarding adjacency" (FA) described in [3] is The notion of "forwarding adjacency" (FA) described in [3] is
essential in propagating existing lightpath information to other essential in propagating existing lightpath information to other
routers. An FA is essentially a virtual link advertised into a link routers. An FA is essentially a virtual link advertised into a link
state routing protocol. Thus, an FA could be described by the same state routing protocol. Thus, an FA could be described by the same
parameters that define resources in any regular link. While it is parameters that define resources in any regular link. While it is
necessary to specify the mechanism for creating an FA, it is not necessary to specify the mechanism for creating an FA, it is not
skipping to change at line 901 skipping to change at line 896
link state representation, replacing the links previously advertised link state representation, replacing the links previously advertised
at the IP-Optical interface. Finally, the details of the optical at the IP-Optical interface. Finally, the details of the optical
network captured in the link state representation is replaced by a network captured in the link state representation is replaced by a
network of FAs. The above scheme is one way to tackle the problem. network of FAs. The above scheme is one way to tackle the problem.
Another approach is to associate appropriate dynamic attributes with Another approach is to associate appropriate dynamic attributes with
link state information, so that a link that cannot be used to link state information, so that a link that cannot be used to
establish a particular type of connection will be appropriately establish a particular type of connection will be appropriately
tagged. Generally, however, there is a great deal of similarity tagged. Generally, however, there is a great deal of similarity
between integrated routing and domain-specific routing (described between integrated routing and domain-specific routing (described
next). Both ultimately deal with the creation of a virtual next). Both ultimately deal with the creation of a virtual
draft-ietf-ipo-framework-04.txt
lightpath topology (which is overlaid over the optical network) to lightpath topology (which is overlaid over the optical network) to
meet certain traffic engineering objectives. meet certain traffic engineering objectives.
draft-ietf-ipo-framework-03.txt
5.2.2 Domain-Specific Routing 5.2.2 Domain-Specific Routing
The domain-specific routing approach supports the augmented The domain-specific routing approach supports the augmented
interconnection model. Under this approach, routing within the interconnection model. Under this approach, routing within the
optical and IP domains are separated, with a standard routing optical and IP domains are separated, with a standard routing
protocol running between domains. This is similar to the IP inter- protocol running between domains. This is similar to the IP inter-
domain routing model. A specific approach for this is considered domain routing model. A specific approach for this is considered
next. It is to be noted that other approaches are equally possible. next. It is to be noted that other approaches are equally possible.
5.2.2.1 Domain-Specific Routing using BGP 5.2.2.1 Domain-Specific Routing using BGP
skipping to change at line 955 skipping to change at line 950
information need not propagate the egress address further, but it information need not propagate the egress address further, but it
must keep the association between external IP addresses and egress must keep the association between external IP addresses and egress
OXC addresses. Specific BGP mechanisms for propagating egress OXC OXC addresses. Specific BGP mechanisms for propagating egress OXC
addresses are to be determined, considering prior examples addresses are to be determined, considering prior examples
described in [9]. When VPNs are implemented, the address prefixes described in [9]. When VPNs are implemented, the address prefixes
advertised by the border OXCs may be accompanied by some VPN advertised by the border OXCs may be accompanied by some VPN
identification (for example, VPN IPv4 addresses, as defined in [9], identification (for example, VPN IPv4 addresses, as defined in [9],
may be used). may be used).
5.2.3 Overlay Routing 5.2.3 Overlay Routing
draft-ietf-ipo-framework-04.txt
The overlay routing approach supports the overlay interconnection The overlay routing approach supports the overlay interconnection
model.Under this approach, an overlay mechanism that allows edge model.Under this approach, an overlay mechanism that allows edge
routers toregister and query for external addresses is implemented. routers toregister and query for external addresses is implemented.
draft-ietf-ipo-framework-03.txt
This is conceptually similar to the address resolution mechanism This is conceptually similar to the address resolution mechanism
used for IP over ATM. Under this approach, the optical network could used for IP over ATM. Under this approach, the optical network could
implement a registry that allows edge routers to register IP implement a registry that allows edge routers to register IP
addresses and VPN identifiers. An edge router may be allowed to addresses and VPN identifiers. An edge router may be allowed to
query for external addresses belonging to the same set of VPNs it query for external addresses belonging to the same set of VPNs it
belongs to. A successful query would return the address of the belongs to. A successful query would return the address of the
egress optical port through which the external destination can be egress optical port through which the external destination can be
reached. reached.
Because IP-optical interface connectivity is limited, the Because IP-optical interface connectivity is limited, the
determination of how many lightpaths must be established and to what determination of how many lightpaths must be established and to what
endpoints are traffic engineering decisions. Furthermore, after an endpoints are traffic engineering decisions. Furthermore, after an
initial set of such lightpaths are established, these may be used as initial set of such lightpaths are established, these may be used as
adjacencies within VPNs for a VPN-wide routing scheme, for example, adjacencies within VPNs for a VPN-wide routing scheme, for example, OSPF. With this approach, an edge router could first determine other
OSPF. With this approach, an edge router could first determine other
edge routers of interest by querying the registry. After it obtains edge routers of interest by querying the registry. After it obtains
the appropriate addresses, an initial overlay lightpath topology may the appropriate addresses, an initial overlay lightpath topology may
be formed. Routing adjacencies may then be established across the be formed. Routing adjacencies may then be established across the
lightpaths and further routing information may be exchanged to lightpaths and further routing information may be exchanged to
establish VPN-wide routing. establish VPN-wide routing.
5.3 Signaling-Related 5.3 Signaling-Related
5.3.1 The Role of MPLS 5.3.1 The Role of MPLS
skipping to change at line 1011 skipping to change at line 1003
IP and optical network are completely separate as shown in Figure 3 IP and optical network are completely separate as shown in Figure 3
below. This separation also implies the separation of IP and optical below. This separation also implies the separation of IP and optical
address spaces (even though the optical network would be using address spaces (even though the optical network would be using
internal IP addressing). While RSVP-TE and LDP can be adapted for internal IP addressing). While RSVP-TE and LDP can be adapted for
UNI signaling, the full functionality of these protocols will not be UNI signaling, the full functionality of these protocols will not be
used. For example, UNI signaling does not require the specification used. For example, UNI signaling does not require the specification
of explicit routes. On the other hand, based on the service of explicit routes. On the other hand, based on the service
attributes, new objects need to be signaled using these protocols as attributes, new objects need to be signaled using these protocols as
described in [5, 6]. described in [5, 6].
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MPLS Signaling UNI Signaling MPLS or other signaling MPLS Signaling UNI Signaling MPLS or other signaling
| |
+-----------------------------+ | +-----------------------------+ +-----------------------------+ | +-----------------------------+
| IP Network | | | Optical Internetwork | | IP Network | | | Optical Internetwork |
| +---------+ +---------+ | | | +---------+ +---------+ | | +---------+ +---------+ | | | +---------+ +---------+ |
| | | | | | | | | | | | | | | | | | | | | | | | | |
| | Router +---+ Router +-----+------+ OXC +---+ OXC | | | | Router +---+ Router +-----+------+ OXC +---+ OXC | |
| | | | | | | | | | | | | | | | | | | | | | | | | |
| +-----+---+ +---+-----+ | | | +-----+---+ +---+-----+ | | +-----+---+ +---+-----+ | | | +-----+---+ +---+-----+ |
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| | | |
IP Layer GMPLS Signaling | Optical Layer GMPLS | IP Layer GMPLS IP Layer GMPLS Signaling | Optical Layer GMPLS | IP Layer GMPLS
| | | |
+--------+ +--------+ | +-------+ +-------+ | +--------+ +--------+ +--------+ | +-------+ +-------+ | +--------+
| | | | | | | | | | | | | | | | | | | | | | | |
| IP LSR +--+ IP LSR +--+--+Optical+--+Optical+-+--+ IP LSR +--- | IP LSR +--+ IP LSR +--+--+Optical+--+Optical+-+--+ IP LSR +---
| | | | | | LSR | | LSR | | | | | | | | | | LSR | | LSR | | | |
+-----+--+ +---+----+ | +-----+-+ +---+---+ | +--------+ +-----+--+ +---+----+ | +-----+-+ +---+---+ | +--------+
Common Address Space, Service Translation Common Address Space, Service Translation
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Figure 4: Unified Services Signaling Model Figure 4: Unified Services Signaling Model
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Thus, as illustrated in Figure 4, the signaling in the case of Thus, as illustrated in Figure 4, the signaling in the case of
unified services is actually multi-layered. The layering is based on unified services is actually multi-layered. The layering is based on
the technology and functionality. As an example, the specific the technology and functionality. As an example, the specific
adaptations of GMPLS signaling for SONET layer (whose functionality adaptations of GMPLS signaling for SONET layer (whose functionality
is transport) are described in [12]. is transport) are described in [12].
5.4 End-to-End Protection Models 5.4 End-to-End Protection Models
Suppose an LSP is established from an ingress IP router to an egress Suppose an LSP is established from an ingress IP router to an egress
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this path be as shown in Figure 5, traversing router interface B this path be as shown in Figure 5, traversing router interface B
in the ingress network, optical ports C (ingress) and D (egress), in the ingress network, optical ports C (ingress) and D (egress),
and router interface E in the egress network. Next, 1+1 protection and router interface E in the egress network. Next, 1+1 protection
is realized separately in each network by establishing a protection is realized separately in each network by establishing a protection
path between points A and B, C and D and E and F. Furthermore, the path between points A and B, C and D and E and F. Furthermore, the
segments B-C and D-E must themselves be 1+1 protected, using drop- segments B-C and D-E must themselves be 1+1 protected, using drop-
side protection. For the segment between C and D, the optical side protection. For the segment between C and D, the optical
internetwork must offer a 1+1 service similar to that offered in the internetwork must offer a 1+1 service similar to that offered in the
IP networks. IP networks.
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+----------------+ +------------------+ +---------------+ +----------------+ +------------------+ +---------------+
| | | | | | | | | | | |
A Ingress IP Net B----C Optical Internet D----E Egress IP Net F A Ingress IP Net B----C Optical Internet D----E Egress IP Net F
| | | | | | | | | | | |
+----------------+ +------------------+ +---------------+ +----------------+ +------------------+ +---------------+
Figure 5: End-to-End Protection Example Figure 5: End-to-End Protection Example
5.4.2 Single-Layer Protection 5.4.2 Single-Layer Protection
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network protocols restore the affected internal segments. Under the network protocols restore the affected internal segments. Under the
second choice, restoration signaling is always end-to-end between IP second choice, restoration signaling is always end-to-end between IP
routers, essentially by-passing the optical internetwork. A result routers, essentially by-passing the optical internetwork. A result
of this is that restoration latency could be higher. In addition, of this is that restoration latency could be higher. In addition,
restoration protocols in the IP layer must run transparently over restoration protocols in the IP layer must run transparently over
the optical internetwork in the overlay mode. IP based recovery the optical internetwork in the overlay mode. IP based recovery
techniques may however be more resource efficient, as it may be techniques may however be more resource efficient, as it may be
possible to convey traffic through the redundant capacity under possible to convey traffic through the redundant capacity under
fault-free scenarios. In particular, it may be possible to utilize fault-free scenarios. In particular, it may be possible to utilize
classification, scheduling, and concepts of forwarding equivalence classification, scheduling, and concepts of forwarding equivalence
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class to route lower class traffic over protect facilities and then class to route lower class traffic over protect facilities and then
possibly preempt them to make way for high priority traffic when possibly preempt them to make way for high priority traffic when
faults occur. faults occur.
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6. IP-based Optical Control Plane Issues 6. IP-based Optical Control Plane Issues
Provisioning and restoring lightpaths end-to-end between IP networks Provisioning and restoring lightpaths end-to-end between IP networks
requires protocol and signaling support within optical sub-networks, requires protocol and signaling support within optical sub-networks,
and across the INNI and ENNI. In this regard, a distinction is made and across the INNI and ENNI. In this regard, a distinction is made
between control procedures within an optical sub-network (Figure 1), between control procedures within an optical sub-network (Figure 1),
between sub-networks, and between networks. The general guideline between sub-networks, and between networks. The general guideline
followed in this framework is to separate these cases, and allow the followed in this framework is to separate these cases, and allow the
possibility that different control procedures are followed inside possibility that different control procedures are followed inside
different sub-networks, while a common set of procedures are different sub-networks, while a common set of procedures are
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many optical channels, each of which contain many sub-channels etc. many optical channels, each of which contain many sub-channels etc.
It is perhaps not reasonable to assume that every sub-channel or It is perhaps not reasonable to assume that every sub-channel or
channel termination, or even OXC ports could be assigned a unique IP channel termination, or even OXC ports could be assigned a unique IP
address. Also, the routing of an optical trail within the network address. Also, the routing of an optical trail within the network
does not depend on the precise termination point information, but does not depend on the precise termination point information, but
rather only on the terminating OXC. Thus, finer granularity rather only on the terminating OXC. Thus, finer granularity
identification of termination points is of relevance only to the identification of termination points is of relevance only to the
terminating OXC and not to intermediate OXCs (of course, resource terminating OXC and not to intermediate OXCs (of course, resource
allocation at each intermediate point would depend on the allocation at each intermediate point would depend on the
granularity of resources requested). This suggests an identification granularity of resources requested). This suggests an identification
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scheme whereby OXCs are identified by a unique IP address and a scheme whereby OXCs are identified by a unique IP address and a
"selector" identifies further fine-grain information of relevance at "selector" identifies further fine-grain information of relevance at
an OXC. This, of course, does not preclude the identification of an OXC. This, of course, does not preclude the identification of
these termination points directly with IP addresses(with a null these termination points directly with IP addresses(with a null
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selector). The selector can be formatted to have adequate number of selector). The selector can be formatted to have adequate number of
bits and a structure that expresses port, channel, sub-channel, etc, bits and a structure that expresses port, channel, sub-channel, etc,
identification. identification.
Within the optical network, the establishment of trail segments Within the optical network, the establishment of trail segments
between adjacent OXCs require the identification of specific port, between adjacent OXCs require the identification of specific port,
channel, sub-channel, etc. With a GMPLS control plane, a label channel, sub-channel, etc. With a GMPLS control plane, a label
serves this function. The structure of the label must be such that serves this function. The structure of the label must be such that
it can encode the required information [12]. it can encode the required information [12].
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Routing within the optical network relies on knowledge of network Routing within the optical network relies on knowledge of network
topology and resource availability. This information may be gathered topology and resource availability. This information may be gathered
and used by a centralized system, or by a distributed link state and used by a centralized system, or by a distributed link state
routing protocol. In either case, the first step towards network- routing protocol. In either case, the first step towards network-
wide link state determination is the discovery of the status of wide link state determination is the discovery of the status of
local links to all neighbors by each OXC. Specifically, each OXC local links to all neighbors by each OXC. Specifically, each OXC
must determine the up/down status of each optical link, the must determine the up/down status of each optical link, the
bandwidth and other parameters of the link, and the identity of the bandwidth and other parameters of the link, and the identity of the
remote end of the link (e.g., remote port number). The last piece of remote end of the link (e.g., remote port number). The last piece of
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information is used to specify an appropriate label when signaling information is used to specify an appropriate label when signaling
for lightpath provisioning. The determination of these parameters for lightpath provisioning. The determination of these parameters
could be based on a combination of manual configuration and an could be based on a combination of manual configuration and an
automated protocol running between adjacent OXCs. The automated protocol running between adjacent OXCs. The
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characteristics of such a protocol would depend on the type of OXCs characteristics of such a protocol would depend on the type of OXCs
that are adjacent (e.g., transparent or opaque). that are adjacent (e.g., transparent or opaque).
Neighbor discovery would typically require in-band communication on Neighbor discovery would typically require in-band communication on
the bearer channels to determine local connectivity and link status. the bearer channels to determine local connectivity and link status.
In the case of opaque OXCs with SONET termination, one instance of a In the case of opaque OXCs with SONET termination, one instance of a
neighbor discovery protocol (e.g., LMP [2]) would run on each OXC neighbor discovery protocol (e.g., LMP [2]) would run on each OXC
port, communicating with the corresponding protocol instance at the port, communicating with the corresponding protocol instance at the
neighboring OXC. The protocol would utilize the SONET overhead bytes neighboring OXC. The protocol would utilize the SONET overhead bytes
to transmit the (configured) local attributes periodically to the to transmit the (configured) local attributes periodically to the
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Topology discovery is the procedure by which the topology and Topology discovery is the procedure by which the topology and
resource state of all the links in a network are determined. This resource state of all the links in a network are determined. This
procedure may be done as part of a link state routing protocol procedure may be done as part of a link state routing protocol
(e.g., OSPF, ISIS), or it can be done via the management plane (in (e.g., OSPF, ISIS), or it can be done via the management plane (in
the case of centralized path computation). The implementation of a the case of centralized path computation). The implementation of a
link state protocol within a network (i.e., across sub-network link state protocol within a network (i.e., across sub-network
boundaries) means that the same protocol runs in OXCs in every sub- boundaries) means that the same protocol runs in OXCs in every sub-
network. If this assumption does not hold then interworking of network. If this assumption does not hold then interworking of
routing between sub-networks is required. This is similar to inter- routing between sub-networks is required. This is similar to inter-
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network routing discussed in Section 6.7. The focus in the following network routing discussed in Section 6.7. The focus in the following
is therefore on standardized link state routing. is therefore on standardized link state routing.
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In general, most of the link state routing functionality is In general, most of the link state routing functionality is
maintained when applied to optical networks. However, the maintained when applied to optical networks. However, the
representation of optical links, as well as some link parameters, representation of optical links, as well as some link parameters,
are changed in this setting. Specifically, are changed in this setting. Specifically,
o The link state information may consist of link bundles [14]. o The link state information may consist of link bundles [14].
Each link bundle is represented as an abstract link in the network Each link bundle is represented as an abstract link in the network
topology. Different bundling representations are possible. For topology. Different bundling representations are possible. For
instance, the parameters of the abstract link may include the instance, the parameters of the abstract link may include the
number, bandwidth and the type of optical links contained in the number, bandwidth and the type of optical links contained in the
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restoration of lightpaths within a network (across the INNI). Local restoration of lightpaths within a network (across the INNI). Local
mechanisms are used to select an alternate link between two adjacent mechanisms are used to select an alternate link between two adjacent
OXCs across the INNI when a failure affects the primary link over OXCs across the INNI when a failure affects the primary link over
which the (protected) lightpath is being routed. Local restoration which the (protected) lightpath is being routed. Local restoration
does not affect the end-to-end route of the lightpath. When local does not affect the end-to-end route of the lightpath. When local
restoration is not possible (e.g., no alternate link is available restoration is not possible (e.g., no alternate link is available
between the adjacent OXCs in question), end-to-end restoration may between the adjacent OXCs in question), end-to-end restoration may
be performed. With this, the affected lightpath may be rerouted over be performed. With this, the affected lightpath may be rerouted over
an alternate path that completely avoids the OXCs or the link an alternate path that completely avoids the OXCs or the link
segment where the failure occurred. For end-to-end restoration, segment where the failure occurred. For end-to-end restoration,
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alternate paths are typically pre-computed. Such back-up paths may alternate paths are typically pre-computed. Such back-up paths may
have to be physically diverse from the corresponding primary paths. have to be physically diverse from the corresponding primary paths.
End-to-end restoration may be based on two types of protection End-to-end restoration may be based on two types of protection
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schemes; "1 + 1" protection or shared protection. Under 1 + 1 schemes; "1 + 1" protection or shared protection. Under 1 + 1
protection, a back-up path is established for the protected primary protection, a back-up path is established for the protected primary
path along a physically diverse route. Both paths are active and the path along a physically diverse route. Both paths are active and the
failure along the primary path results in an immediate switch-over failure along the primary path results in an immediate switch-over
to the back-up path. Under shared protection, back-up paths to the back-up path. Under shared protection, back-up paths
corresponding to physically diverse primary paths may share the same corresponding to physically diverse primary paths may share the same
network resources. When a failure affects a primary path, it is network resources. When a failure affects a primary path, it is
assumed that the same failure will not affect the other primary assumed that the same failure will not affect the other primary
paths whose back-ups share resources. paths whose back-ups share resources.
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implications on optical link bundling. Specifically, a bundled LSA implications on optical link bundling. Specifically, a bundled LSA
must include adequate information such that a remote OXC can must include adequate information such that a remote OXC can
determine the resource availability under each SRLG that the bundled determine the resource availability under each SRLG that the bundled
link refers to, and the relationship between links belonging to link refers to, and the relationship between links belonging to
different SRLGs in the bundle. For example, considering Figure 3, different SRLGs in the bundle. For example, considering Figure 3,
if links 1,2,3 and 4 are bundled together in an LSA, the bundled LSA if links 1,2,3 and 4 are bundled together in an LSA, the bundled LSA
must indicate that there are three SRLGs which are part of the must indicate that there are three SRLGs which are part of the
bundle (i.e., 1, 2 and 3), and that links in SRLGs 2 and 3 are also bundle (i.e., 1, 2 and 3), and that links in SRLGs 2 and 3 are also
part of SRLG 1. part of SRLG 1.
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To encode the SRLG relationships in a link bundle LSA, only links To encode the SRLG relationships in a link bundle LSA, only links
which belong to exactly the same set of SRLGs must be bundled which belong to exactly the same set of SRLGs must be bundled
together. With reference to Figure 3, for example, two bundles can together. With reference to Figure 3, for example, two bundles can
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be advertised for links between OXC1 and OXC2, with the following be advertised for links between OXC1 and OXC2, with the following
information: information:
Bundle No. SRLGs Link Type Number Other Info Bundle No. SRLGs Link Type Number Other Info
---------- ----- --------- ------ ---------- ---------- ----- --------- ------ ----------
1 1,2 OC-48 3 --- 1 1,2 OC-48 3 ---
2 1,3 OC-192 1 --- 2 1,3 OC-192 1 ---
Assuming that the above information is available for each bundle at Assuming that the above information is available for each bundle at
every node, there are several approaches possible for path every node, there are several approaches possible for path
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also be established specifying only which SRLGs to avoid in a also be established specifying only which SRLGs to avoid in a
given segment, rather than which bundles to use. This would given segment, rather than which bundles to use. This would
maximize the chances of establishing the back-up path. maximize the chances of establishing the back-up path.
2. The primary path and the back-up path are computed together in 2. The primary path and the back-up path are computed together in
one step, for example, using Suurbaale's algorithm [18]. In this one step, for example, using Suurbaale's algorithm [18]. In this
case, the paths must be computed using specific bundle case, the paths must be computed using specific bundle
information. information.
To summarize, it is essential to capture sufficient information in To summarize, it is essential to capture sufficient information in
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link bundle LSAs to accommodate different path computation link bundle LSAs to accommodate different path computation
procedures and to maximize the chances of successful path procedures and to maximize the chances of successful path
establishment. Depending on the path computation procedure used, establishment. Depending on the path computation procedure used,
the type of support needed during path establishment (e.g., the the type of support needed during path establishment (e.g., the
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recording of link group or SRLG information during path recording of link group or SRLG information during path
establishment) may differ. establishment) may differ.
When shared protection is used, the route computation algorithm must When shared protection is used, the route computation algorithm must
take into account the possibility of sharing links among multiple take into account the possibility of sharing links among multiple
back-up paths. Under shared protection, the back-up paths back-up paths. Under shared protection, the back-up paths
corresponding to SRLG-disjoint primary paths can be assigned the corresponding to SRLG-disjoint primary paths can be assigned the
same links. The assumption here is that since the primary paths are same links. The assumption here is that since the primary paths are
not routed over links that have the same SRLG, a given failure will not routed over links that have the same SRLG, a given failure will
affect only one of them. Furthermore, it is assumed that multiple affect only one of them. Furthermore, it is assumed that multiple
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coordinated fashion. This coordination is akin to selecting incoming coordinated fashion. This coordination is akin to selecting incoming
and outgoing labels in a label-switched environment. Thus, protocols and outgoing labels in a label-switched environment. Thus, protocols
like RSVP-TE [11] and CR-LDP [10] can be used across the INNI for like RSVP-TE [11] and CR-LDP [10] can be used across the INNI for
this. A few new concerns, however, must be addressed. this. A few new concerns, however, must be addressed.
6.6.1 Bi-Directional Lightpath Establishment 6.6.1 Bi-Directional Lightpath Establishment
Lightpaths are typically bi-directional. That is, the output port Lightpaths are typically bi-directional. That is, the output port
selected at an OXC for the forward direction is also the input port selected at an OXC for the forward direction is also the input port
for the reverse direction of the path. Since signaling for optical for the reverse direction of the path. Since signaling for optical
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paths may be autonomously initiated by different nodes, it is paths may be autonomously initiated by different nodes, it is
possible that two path set-up attempts are in progress at the same possible that two path set-up attempts are in progress at the same
time. Specifically, while setting up an optical path, an OXC A may time. Specifically, while setting up an optical path, an OXC A may
select output port i which is connected to input port j of the select output port i which is connected to input port j of the
"next" OXC B. Concurrently, OXC B may select output port j for "next" OXC B. Concurrently, OXC B may select output port j for
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setting up a different optical path, where the "next" OXC is A. This setting up a different optical path, where the "next" OXC is A. This
results in a "collision". Similarly, when WDM functionality is built results in a "collision". Similarly, when WDM functionality is built
into OXCs, a collision occurs when adjacent OXCs choose directly into OXCs, a collision occurs when adjacent OXCs choose directly
connected output ports and the same wavelength for two different connected output ports and the same wavelength for two different
optical paths. There are two ways to deal with such collisions. optical paths. There are two ways to deal with such collisions.
First, collisions may be detected and the involved paths may be torn First, collisions may be detected and the involved paths may be torn
down and re-established. Or, collisions may be avoided altogether. down and re-established. Or, collisions may be avoided altogether.
6.6.2 Failure Recovery 6.6.2 Failure Recovery
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Signaling to establish a "1+1" back-up path is relatively straight- Signaling to establish a "1+1" back-up path is relatively straight-
forward. This signaling is very similar to signaling used for forward. This signaling is very similar to signaling used for
establishing the primary path. Signaling to establish a shared back- establishing the primary path. Signaling to establish a shared back-
up path is a little bit different. Here, each OXC must understand up path is a little bit different. Here, each OXC must understand
which back-up paths can share resources. The signaling message must which back-up paths can share resources. The signaling message must
itself indicate shared reservation. The sharing rule is as described itself indicate shared reservation. The sharing rule is as described
in Section 6.4: back-up paths corresponding to physically diverse in Section 6.4: back-up paths corresponding to physically diverse
primary paths may share the same network resources. It is primary paths may share the same network resources. It is
therefore necessary for the signaling message to carry adequate therefore necessary for the signaling message to carry adequate
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information that allows an OXC to verify that back-up paths that information that allows an OXC to verify that back-up paths that
share a certain resources are allowed to do so. share a certain resources are allowed to do so.
Under both 1+1 and shared protection, the activation phase has two Under both 1+1 and shared protection, the activation phase has two
parts: propagation of failure information to the source OXC from the parts: propagation of failure information to the source OXC from the
point of failure, and activation of the back-up path. The signaling point of failure, and activation of the back-up path. The signaling
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for these two phases must be very fast in order to realize response for these two phases must be very fast in order to realize response
times in the order of tens of milliseconds. When optical links are times in the order of tens of milliseconds. When optical links are
SONET-based, in-band signals may be used, resulting in quick SONET-based, in-band signals may be used, resulting in quick
response. With out-of-band control, it is necessary to consider response. With out-of-band control, it is necessary to consider
fast signaling over the control channel using very short IP packets fast signaling over the control channel using very short IP packets
and prioritized processing. While it is possible to use RSVP or CR- and prioritized processing. While it is possible to use RSVP or CR-
LDP for activating protection paths, these protocols do not provide LDP for activating protection paths, these protocols do not provide
any means to give priority to restoration signaling as opposed to any means to give priority to restoration signaling as opposed to
signaling for provisioning. For instance, it is possible for a signaling for provisioning. For instance, it is possible for a
restoration-related RSVP message to be queued behind a number of restoration-related RSVP message to be queued behind a number of
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o A protocol is required for determining reachability of end-points o A protocol is required for determining reachability of end-points
across networks. across networks.
o A standard signaling protocol is required for provisioning o A standard signaling protocol is required for provisioning
lightpaths across networks. lightpaths across networks.
o A standard procedure is required for the restoration of lightpaths o A standard procedure is required for the restoration of lightpaths
across networks. across networks.
o Support for policies that affect the flow of control information o Support for policies that affect the flow of control information across networks will be required.
across networks will be required.
The IP-centric control architecture for optical networks can be The IP-centric control architecture for optical networks can be
extended to satisfy the functional requirements of optical extended to satisfy the functional requirements of optical
internetworking. Routing and signaling interaction between optical internetworking. Routing and signaling interaction between optical
networks can be standardized across the ENNI (Figure 1). The networks can be standardized across the ENNI (Figure 1). The
functionality provided across ENNI is as follows. functionality provided across ENNI is as follows.
6.7.1 Neighbor Discovery 6.7.1 Neighbor Discovery
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Neighbor discovery procedure, as described in Section 6.2, can be Neighbor discovery procedure, as described in Section 6.2, can be
used for this. Indeed, a single protocol should be standardized for used for this. Indeed, a single protocol should be standardized for
neighbor discovery within and across networks. neighbor discovery within and across networks.
6.7.2 Addressing and Routing Model 6.7.2 Addressing and Routing Model
The addressing mechanisms described in Section 6.1 can be used to The addressing mechanisms described in Section 6.1 can be used to
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identify OXCs, ports, channels and sub-channels in each network. identify OXCs, ports, channels and sub-channels in each network.
It is essential that the OXC IP addresses are unique within the It is essential that the OXC IP addresses are unique within the
internetwork. internetwork.
Provisioning an end-to-end lightpath across multiple networks Provisioning an end-to-end lightpath across multiple networks
involves the establishment of path segments in each network involves the establishment of path segments in each network
sequentially. Thus, a path segment is established from the source sequentially. Thus, a path segment is established from the source
OXC to a border OXC in the source network. From this border OXC, OXC to a border OXC in the source network. From this border OXC,
signaling across NNI is used to establish a path segment to a border signaling across NNI is used to establish a path segment to a border
OXC in the next network. Provisioning then continues in the next OXC in the next network. Provisioning then continues in the next
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7.2 Wavelength Conversion 7.2 Wavelength Conversion
Some form of wavelength conversion may exist at some switching Some form of wavelength conversion may exist at some switching
elements. This however may not be the case in some pure optical elements. This however may not be the case in some pure optical
switching elements. A switching element is essentially anything switching elements. A switching element is essentially anything
more sophisticated than a simple repeater, that is capable of more sophisticated than a simple repeater, that is capable of
switching and converting a wavelength Lambda(k) from an input port switching and converting a wavelength Lambda(k) from an input port
to a wavelength Lambda(l) on an output port. In this display, it to a wavelength Lambda(l) on an output port. In this display, it
is not necessarily the case that Lambda(k) = Lambda(l), nor is it is not necessarily the case that Lambda(k) = Lambda(l), nor is it
draft-ietf-ipo-framework-04.txt
necessarily the case that the data carried on Lambda(k) is switched necessarily the case that the data carried on Lambda(k) is switched
through the device without being examined or modified. through the device without being examined or modified.
It is not necessary to have a wavelength converter at every It is not necessary to have a wavelength converter at every
switching element. A number of studies have attempted to address switching element. A number of studies have attempted to address
the issue of the value of wavelength conversion in an optical the issue of the value of wavelength conversion in an optical
network. Such studies typically use the blocking probability (the network. Such studies typically use the blocking probability (the
probability that a lightpath cannot be established because the probability that a lightpath cannot be established because the
draft-ietf-ipo-framework-03.txt
requisite wavelengths are not available) as a metric to adjudicate requisite wavelengths are not available) as a metric to adjudicate
the effectiveness of wavelength conversion. The IP over optical the effectiveness of wavelength conversion. The IP over optical
architecture must take into account hybrid networks with some OXCs architecture must take into account hybrid networks with some OXCs
capable of wavelength conversion and others incapable of this. The capable of wavelength conversion and others incapable of this. The
GMPLS "label set" mechanism [4] supports the selection of the same GMPLS "label set" mechanism [4] supports the selection of the same
label (i.e., wavelength) across an NNI. label (i.e., wavelength) across an NNI.
7.3 Service Provider Peering Points 7.3 Service Provider Peering Points
There are proposed inter-network interconnect models which allow There are proposed inter-network interconnect models which allow
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complexity of proposed solutions, stability concerns, and lack of complexity of proposed solutions, stability concerns, and lack of
true economic drivers for this type of service. This document true economic drivers for this type of service. This document
assumes that this paradigm will not change and that highly dynamic, assumes that this paradigm will not change and that highly dynamic,
data-driven shortcut lightpath setups are for future investigation. data-driven shortcut lightpath setups are for future investigation.
Instead, the optical channel trails and lightpaths that are expected Instead, the optical channel trails and lightpaths that are expected
to be widely used at the initial phases in the evolution of IP over to be widely used at the initial phases in the evolution of IP over
optical networks will include the following: optical networks will include the following:
o Dynamic connections for control plane traffic and default path o Dynamic connections for control plane traffic and default path
routed data traffic, routed data traffic,
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o Establishment and re-arrangement of arbitrary virtual topologies o Establishment and re-arrangement of arbitrary virtual topologies
over rings and other physical layer topologies. over rings and other physical layer topologies.
o Use of stable traffic engineering control systems to engineer o Use of stable traffic engineering control systems to engineer
lightpath connections to enhance network performance, either for lightpath connections to enhance network performance, either for
explicit demand based QoS reasons or for load balancing). explicit demand based QoS reasons or for load balancing).
Other issues surrounding dynamic connection setup within the core Other issues surrounding dynamic connection setup within the core
draft-ietf-ipo-framework-03.txt
center around resource usage at the edge of the optical domain. center around resource usage at the edge of the optical domain.
One potential issue pertains to the number of flows that can be One potential issue pertains to the number of flows that can be
processed by an ingress or egress network element either because of processed by an ingress or egress network element either because of
aggregate bandwidth limitations or because of a limitation on the aggregate bandwidth limitations or because of a limitation on the
number of flows (e.g., lightpaths) that can be processed number of flows (e.g., lightpaths) that can be processed
concurrently. concurrently.
Another possible short term reason for dynamic shortcut lightpath Another possible short term reason for dynamic shortcut lightpath
setup would be to quickly pre-provision paths based on some criteria setup would be to quickly pre-provision paths based on some criteria
(e.g., a corporate executive wants a high bandwidth reliable (e.g., a corporate executive wants a high bandwidth reliable
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server in order to set up a lightpath from the source to the server in order to set up a lightpath from the source to the
destination. The server would then check to see if such a lightpath destination. The server would then check to see if such a lightpath
can be established based on prevailing conditions. Furthermore, can be established based on prevailing conditions. Furthermore,
depending on the specifics of the model, the server may either setup depending on the specifics of the model, the server may either setup
the lightpath on behalf of the client or provide the necessary the lightpath on behalf of the client or provide the necessary
information to the client or to some other entity to allow the information to the client or to some other entity to allow the
lightpath to be instantiated. lightpath to be instantiated.
Centralization aids in implementing complex capacity optimization Centralization aids in implementing complex capacity optimization
schemes, and may be the near-term provisioning solution in optical schemes, and may be the near-term provisioning solution in optical
draft-ietf-ipo-framework-04.txt
networks with interconnected multi-vendor optical sub-networks. In networks with interconnected multi-vendor optical sub-networks. In
the long term, however, the distributed solution with centralization the long term, however, the distributed solution with centralization
of some control procedures (e.g., traffic engineering) is likely to of some control procedures (e.g., traffic engineering) is likely to
be the approach followed. be the approach followed.
draft-ietf-ipo-framework-03.txt
7.6 Optical Networks with Additional Configurable Components 7.6 Optical Networks with Additional Configurable Components
Thus far, this memo has focused mainly on IP over optical networks Thus far, this memo has focused mainly on IP over optical networks
where the cross-connect is the basic dynamically re-configurable where the cross-connect is the basic dynamically re-configurable
device in the optical network. Recently, as a consequence of device in the optical network. Recently, as a consequence of
technology evolution, various types of re-configurable optical technology evolution, various types of re-configurable optical
components are now available, including tunable lasers, tunable components are now available, including tunable lasers, tunable
filters, etc. Under certain circumstances, it may be necessary to filters, etc. Under certain circumstances, it may be necessary to
parameterize the characteristics of these components and advertise parameterize the characteristics of these components and advertise
them within the control plane. This aspect is left for further them within the control plane. This aspect is left for further
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dispersion and polarization mode dispersion), cross-talk, and non- dispersion and polarization mode dispersion), cross-talk, and non-
linear effects. In such networks, the feasibility of a path between linear effects. In such networks, the feasibility of a path between
two nodes is no longer simply a function of topology and resource two nodes is no longer simply a function of topology and resource
availability but will also depend on the accumulation of impairments availability but will also depend on the accumulation of impairments
along the path. If the impairment accumulation is excessive, the along the path. If the impairment accumulation is excessive, the
optical signal to noise ratio (OSNR) and hence the electrical bit optical signal to noise ratio (OSNR) and hence the electrical bit
error rate (BER) at the destination node may exceed prescribed error rate (BER) at the destination node may exceed prescribed
thresholds, making the resultant optical channel unusable for data thresholds, making the resultant optical channel unusable for data
communication. The challenge in the development of IP-based control communication. The challenge in the development of IP-based control
plane for optical networks is to abstract these peculiar plane for optical networks is to abstract these peculiar
draft-ietf-ipo-framework-04.txt
characteristics of the optical layer [19] in a generic fashion, so characteristics of the optical layer [19] in a generic fashion, so
that they can be used for path computation. that they can be used for path computation.
8. Evolution Path for IP over Optical Architecture 8. Evolution Path for IP over Optical Architecture
The architectural models described in Section 5 imply a certain The architectural models described in Section 5 imply a certain
degree of implementation complexity. Specifically, the overlay degree of implementation complexity. Specifically, the overlay
model was described as the least complex for near term deployment model was described as the least complex for near term deployment
draft-ietf-ipo-framework-03.txt
and the peer model the most complex. Nevertheless, each model has and the peer model the most complex. Nevertheless, each model has
certain advantages and this raises the question as to the evolution certain advantages and this raises the question as to the evolution
path for IP over optical network architectures. path for IP over optical network architectures.
The evolution approach recommended in this framework is the The evolution approach recommended in this framework is the
definition of capability sets that start with simpler functionality definition of capability sets that start with simpler functionality
in the beginning and include more complex functionality later. In in the beginning and include more complex functionality later. In
this regard, it is realistic to expect that initial IP over optical this regard, it is realistic to expect that initial IP over optical
deployments will be based on the domain services model (with overlay deployments will be based on the domain services model (with overlay
interconnection), with no routing exchange between the IP and interconnection), with no routing exchange between the IP and
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integrated into operational infrastructures. The introduction of integrated into operational infrastructures. The introduction of
routing capabilities can be expected to occur in a phased approach. routing capabilities can be expected to occur in a phased approach.
It is likely that in the first phase, service providers will either It is likely that in the first phase, service providers will either
upgrade existing local element management (EMS) software with upgrade existing local element management (EMS) software with
additional control plane capabilities (and perhaps the hardware as additional control plane capabilities (and perhaps the hardware as
well), or upgrade the NMS software in order to introduce some degree well), or upgrade the NMS software in order to introduce some degree
of automation within each optical subnetwork. For this reason, it of automation within each optical subnetwork. For this reason, it
may be desirable to partition the network into subnetworks and may be desirable to partition the network into subnetworks and
introduce IGP interoperability within each subnetwork (i.e. at the introduce IGP interoperability within each subnetwork (i.e. at the
I-NNI level), and employ either static or signaled interoperability I-NNI level), and employ either static or signaled interoperability
draft-ietf-ipo-framework-04.txt
between subnetworks. Consequently, it can be envisioned that the between subnetworks. Consequently, it can be envisioned that the
first phase in the evolution towards network level control plane first phase in the evolution towards network level control plane
interoperability in IP over Optical networks will be organized interoperability in IP over Optical networks will be organized
around a system of optical subnetworks which are interconnected around a system of optical subnetworks which are interconnected
statically (or dynamically in a signaled configuration). During this statically (or dynamically in a signaled configuration). During this
phase, an overlay interconnection model will be used between the phase, an overlay interconnection model will be used between the
optical network itself and external IP and MPLS routers (as optical network itself and external IP and MPLS routers (as
described in Section 5.2.3). described in Section 5.2.3).
draft-ietf-ipo-framework-03.txt
Progressing with this phased approach to IPO routing Progressing with this phased approach to IPO routing
interoperabibility evolution, the next level of integration will be interoperabibility evolution, the next level of integration will be
achieved when a single carrier provides dynamic optical routing achieved when a single carrier provides dynamic optical routing
interoperability between subnetworks and between domains. In order interoperability between subnetworks and between domains. In order
to become completely independent of the network switching capability to become completely independent of the network switching capability
within subnetworks and across domains, routing information exchange within subnetworks and across domains, routing information exchange
may need to be enabled at the UNI level. This would constitute a may need to be enabled at the UNI level. This would constitute a
significant evolution: even if the routing instances are kept significant evolution: even if the routing instances are kept
separate and independent, it would still be possible to dynamicallhy separate and independent, it would still be possible to dynamicallhy
exchange reachability and other types of routing information. exchange reachability and other types of routing information.
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networks (independent of internal switching capability) would be networks (independent of internal switching capability) would be
capable of exchanging routing information with peers across the E- capable of exchanging routing information with peers across the E-
NNI. NNI.
Another alternative would be for private networks to bypass these Another alternative would be for private networks to bypass these
intermediate steps and directly consider an integrated routing model intermediate steps and directly consider an integrated routing model
from the onset. This direct evolution strategy is realistic, but is from the onset. This direct evolution strategy is realistic, but is
more likely to occur in operational contexts where both the IP (or more likely to occur in operational contexts where both the IP (or
MPLS) and optical networks are built simultaneously, using equipment MPLS) and optical networks are built simultaneously, using equipment
from a single source or from multiple sources that are closely from a single source or from multiple sources that are closely
affiliated. In any case, due the current lack of operational affiliated. In any case, due to the current lack of operational
experience in managing this degree of control plane interaction in a experience in managing this degree of control plane interaction in a
heterogenous network (these issues may exist even if the hardware heterogeneous network (these issues may exist even if the hardware
and software originate from the same vendor), an augmented model is and software originate from the same vendor), an augmented model is
likely to be the most viable initial option. Alternatively, a very likely to be the most viable initial option. Alternatively, a very
modular or hierarchical peer model may be contemplated. There may be modular or hierarchical peer model may be contemplated. There may be
other challenges (not just of a technical, but also administrative other challenges (not just of a technical, but also administrative
and even political issues) that may be need to be resolved in order and even political issues) that may need to be resolved in order to
to achieve full a peer model at the routing level in a multi- achieve full a peer model at the routing level in a multi-technology
technology and multi-vendor environment. Ultimately, the main and multi-vendor environment. Ultimately, the main technical
technical improvement would likely arise from efficiencies derived improvement would likely arise from efficiencies derived from the
from the integration of traffic-engineering capabilities in the integration of traffic-engineering capabilities in the dynamic
dynamic inter-domain routing environments. inter-domain routing environments.
9. Security Considerations 9. Security Considerations
The architectural framework described in this document requires The architectural framework described in this document requires a
different protocol mechanisms for its realization. Specifically, the number of different protocol mechanisms for its realization.
role of neighbor discovery, routing and signaling protocols were Specifically, the role of neighbor discovery, routing, and signaling
described in previous sections. The general security issues that protocols were highlighted in previous sections. The general
arise with these protocols include: security issues that arise with these protocols include:
draft-ietf-ipo-framework-04.txt
o The authentication of entities exchanging information o The authentication of entities exchanging information
(signaling, routing or link management) across a control (e.g., signaling, routing, or link management) across a control
interface; interface;
o Ensuring the integrity of the information exchanged across the o Ensuring the integrity of the information exchanged across the interface;
interface, and
draft-ietf-ipo-framework-03.txt
o Protection of the control mechanisms from outside interference o Protection of the control mechanisms from intrusions and other
modes of outside interference.
Because optical connections may carry high volumes of data and Because optical connections may carry high volumes of traffic and
consume significant network resources, mechanisms are required to are generally quite expensive, mechanisms are required to safeguard
safeguard an optical network against unauthorized use of network optical networks against intrusions and unauthorized utilization of
resources. network resources.
In addition to the security aspects related to the control plane, In addition to the security aspects relating to the control plane,
the data plane must also be protected from external interference. the data plane must also be protected from external interference.
An important consideration in optical networks is the separation of
control channels from data channels. This decoupling implies that
the state of the bearer channels carrying user traffic cannot be
inferred from the state of the control channels. Similarly, the
state of the control channels cannot be inferred from the state of
the data channels. The potential security implications of this
decoupling should be taken into account in the design of pertinent
control protocols and in the operation of IPO networks.
Another issue in IPO networks concerns the fact that the underlying
optical network elements may be invisible to IP client nodes,
especially in the overlay model. This means that traditional IP
tools such as traceroute cannot be used by client IP nodes to detect
attacks within the optical domain.
For the aforementioned reasons, the output of the routing protocol
security (RPSEC) efforts within the IETF should be considered in the
design of control protocols for optical networks.
In Section 2, the concept of a trust domain was defined as a network
under a single technical administration in which adequate security
measures are established to prevent unauthorized intrusion from
outside the domain. It should be strongly noted that within a trust
domain, any subverted node can send control messages which can
compromise the entire network.
9.1 General security aspects 9.1 General security aspects
Communication protocols usually require two main security Communication protocols usually require two main security
mechanisms: authentication and confidentiality. Authentication mechanisms: authentication and confidentiality. Authentication
mechanisms ensure data origin verification and message integrity so mechanisms ensure data origin verification and message integrity so
that unauthorized operations can be detectedd and discarded. For that intrusions and unauthorized operations can be detected and
example, with reference to Figure 1, message authentication service draft-ietf-ipo-framework-04.txt
can prevent a malicious IP client from mounting a denial of service
attack against the optical network by inserting an excessive number mitigated. For example, with reference to Figure 1, message
of UNI connection creation requests. Additionally, authentication authentication can prevent a malicious IP client from mounting a
mechanisms can provide denial of service attack against the optical network by invoking an
excessive number of connection creation requests across the UNI
interface. Additionally, authentication mechanisms can provide
1. Replay protection, which detects and rejects attempts to 1. Replay protection, which detects and rejects attempts to
reorder, duplicate, truncate, or otherwise tamper with the reorder, duplicate, truncate, or otherwise tamper with the
proper sequence of messages, and proper sequence of messages, and
2. Non-repudiation, which may be desirable for accounting and 2. Non-repudiation, which may be desirable for accounting and
billing purposes. billing purposes.
Confidentiality of signaling messages is also likely to be Confidentiality of signaling messages is also likely to be
desirable, especially in cases where message attributes include desirable, especially in cases where message attributes include
information private to the communicating parties (client and optical information of a private nature to the communicating parties (client
network operator). Examples of such attributes include account and optical network operator). Examples of such attributes include
numbers, contract identification numbers, etc, exchanged over the account numbers, contract identification numbers, etc, exchanged
UNI (Figure 1). over the UNI (Figure 1).
The case of non-co-located equipment presents increases security The case of non-co-located equipment presents increased security
requirements. In this scenario, the signaling (or routing) peers may threats. In this scenario, the signaling (or routing) peers may be
be connected using an external network. Since such a network could connected using an external network. Since such a network could be
be outside the control of the optical (or client) network operator, outside the control of the optical (or client) network operator,
control communication between peers may be subject to increased control communication between peers may be subject to increased
security threats, such as address spoofing, eavesdropping and security threats, such as address spoofing, eavesdropping and
unauthorized intrusion attempts. To counter these threats , unauthorized intrusion attempts. To counter these threats ,
appropriate security mechanisms have to be employed to protect the appropriate security mechanisms have to be employed to protect the
signaling and control channel(s). signaling and control channel(s).
Requests for optical connections from client networks must be Requests for optical connections from client networks must be
filtered against policy to guard against security infringements and filtered against policy to guard against security infringements and
excess resource consumption. excess resource consumption.
There may be a need for confidentiality for SRLGs in some There may be a need for confidentiality of SRLGs in some
circumstances. circumstances.
draft-ietf-ipo-framework-03.txt
Optical networks may also be subject to subtle forms of denial of Optical networks may also be subject to subtle forms of denial of
service attacks. An example of this would be requests for optical service attacks. An example of this would be requests for optical
connections with explicit routes that induce a high degree of connections with explicit routes that induce a high degree of
blocking for subsequent requests. This aspect might require some blocking for subsequent requests. This aspect might require some
global coordination of resource allocation. global coordination of resource allocation.
9.2 Protocol Mechanisms Another related form of subtle denial of service attack could occur
when improbably optical paths are requested (i.e., paths within the
network for which resources were insufficiently provisioned). Such
requests for improbable paths may consume ports on optical switching
elements within the network resulting in denial of service for
subsequent connection requests.
The security-related mechanisms required in IP-centric control 9.2 Security Considerations for Protocol Mechanisms
protocols would depend on the specific security requirements. Such draft-ietf-ipo-framework-04.txt
details are beyond the scope of this document and hence are not
considered further. The security mechanisms required for IP-centric control plane
protocols for optical networks would depend on the characteristics
of the specific protocols and other pertinent security requirements.
Such details are beyond the scope of this document and hence are not
considered further. Nevertheless, it must be stated that such
control protocols must take into account the issues associated with
the separation of control channels from data channels in switched
optical networks, and the magnitude and extent of service
interruptions within the IP domain that could result from outages
within the optical domain.
10. Summary and Conclusions 10. Summary and Conclusions
The objective of this document was to define a framework for IP over The objective of this document was to define a framework for IP over
optical networks, considering the service models, routing and optical networks, considering the service models, routing and
signaling issues. There are a diversity of choices, as described signaling issues. There are a diversity of choices, as described
in this document, for IP-optical interconnection, service models in this document, for IP-optical interconnection, service models
and protocol mechanisms. The approach advocated in this document and protocol mechanisms. The approach advocated in this document
was to allow different service models and proprietary enhancements was to allow different service models and proprietary enhancements
in optical networks, and define complementary signaling and in optical networks, and define complementary signaling and
skipping to change at line 2063 skipping to change at line 2093
with overlay interconnection that eventually evolves to support full with overlay interconnection that eventually evolves to support full
peer interaction. peer interaction.
11. References 11. References
Note: All references are informative: Note: All references are informative:
1. D. Awduche and Y. Rekhter, , "Multi-Protocol 1. D. Awduche and Y. Rekhter, , "Multi-Protocol
Lambda Switching: Combining MPLS Traffic Engineering Control With Lambda Switching: Combining MPLS Traffic Engineering Control With
Optical Crossconnects," IEEE Communications Magazine, March 2001. Optical Crossconnects," IEEE Communications Magazine, March 2001.
2. J. P. Lang, et. al., "Link Management Protocol," Internet Draft, 2. J. P. Lang, et. al., "Link Management Protocol," Internet Draft,
Work in progress. Work in progress.
3. K. Kompella and Y. Rekhter, "LSP Hierarchy with MPLS TE," 3. K. Kompella and Y. Rekhter, "LSP Hierarchy with MPLS TE,"
Internet Draft, Work in progress. Internet Draft, Work in progress.
4. P. Ashwood-Smith et. al, "Generalized MPLS - Signaling Functional 4. L. Berger, et. al, "Generalized MPLS - Signaling Functional
Description", Internet Draft, Work in Progress. Description", RFC 3471.
5. B. Rajagopalan, "LDP and RSVP Extensions for Optical UNI
Signaling," Internet Draft, Work in Progress.
draft-ietf-ipo-framework-03.txt 5. B. Rajagopalan, "Documentation of IANA Assignments for LDP, RSVP
and RSVP-TE Extensions for Optical UNI Signaling," RFC 3476.
6. The Optical Interworking Forum, "UNI 1.0 Signaling 6. The Optical Interworking Forum, "UNI 1.0 Signaling
Specification," December, 2001. Specification," December, 2001.
draft-ietf-ipo-framework-04.txt
7. K. Kompella et al, "OSPF Extensions in Support of Generalized 7. K. Kompella et al, "OSPF Extensions in Support of Generalized
MPLS," Internet Draft, Work in Progress. MPLS," Internet Draft, Work in Progress.
8. Y. Rekhter and T. Li, "A Border Gateway Protocol 4 (BGP4)",RFC 8. Y. Rekhter and T. Li, "A Border Gateway Protocol 4 (BGP4)",RFC
1771, March, 1995. 1771, March, 1995.
9. E. Rosen and Y. Rekhter, "BGP/MPLS VPNs", RFC 2547, March, 1999. 9. E. Rosen and Y. Rekhter, "BGP/MPLS VPNs", RFC 2547, March, 1999.
10. P. Ashwood-Smith, et. al., "Generalized MPLS - CR-LDP Signaling 10. P. Ashwood-Smith, et. al., "Generalized MPLS - CR-LDP Signaling
Functional Description," Internet Draft, Work in Progress. Functional Description," RFC 3472.
11. P. Ashwood-Smith, et. al., "Generalized MPLS - RSVP-TE 11. L. Berger, et. al., "Generalized MPLS - RSVP-TE Signaling
Signaling Functional Description", Internet Draft, Work in Functional Description", RFC 3473.
Progress.
12. E. Mannie, et. al., "GMPLS Extensions for SONET/SDH Control," 12. E. Mannie, et. al., "GMPLS Extensions for SONET/SDH Control,"
Internet Draft, Work in Progress. Internet Draft, Work in Progress.
13. B. Doshi, S. Dravida, P. Harshavardhana, et. al, "Optical 13. B. Doshi, S. Dravida, P. Harshavardhana, et. al, "Optical
Network Design and Restoration," Bell Labs Technical Journal, Network Design and Restoration," Bell Labs Technical Journal,
Jan-March, 1999. Jan-March, 1999.
14. K. Kompella, et al., "Link Bundling in MPLS Traffic 14. K. Kompella, et al., "Link Bundling in MPLS Traffic
Engineering," Internet Draft, Work in Progress. Engineering," Internet Draft, Work in Progress.
skipping to change at line 2129 skipping to change at line 2157
1974. 1974.
19. A. Chiu et al., "Impairments and Other Constraints On Optical 19. A. Chiu et al., "Impairments and Other Constraints On Optical
Layer Routing", Internet Draft, Work in Progress. Layer Routing", Internet Draft, Work in Progress.
12. Acknowledgments 12. Acknowledgments
We would like to thank Zouheir Mansourati (Movaz Networks), Ian We would like to thank Zouheir Mansourati (Movaz Networks), Ian
Duncan (Nortel Networks), Dimitri Papadimitriou (Alcatel), and Duncan (Nortel Networks), Dimitri Papadimitriou (Alcatel), and
Dimitrios Pendarakis (Tellium) for their contributions to this Dimitrios Pendarakis (Tellium) for their contributions to this
document. document. The Security Considerations section was revised to reflect
input from Scott Bradner and Steve Bellovin.
draft-ietf-ipo-framework-03.txt draft-ietf-ipo-framework-04.txt
13. Contributors 13. Contributors
Contributors are listed alphabetically. Contributors are listed alphabetically.
Daniel O. Awduche Daniel O. Awduche
Isocore Isocore
8201 Greensboro Drive, Suite 102, 8201 Greensboro Drive, Suite 102,
McLean, VA 22102 McLean, VA 22102
Phone: 703-298-5291 Phone: 703-298-5291
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