draft-ietf-mpls-tp-requirements-09.txt   draft-ietf-mpls-tp-requirements-10.txt 
MPLS Working Group B. Niven-Jenkins, Ed. MPLS Working Group B. Niven-Jenkins, Ed.
Internet-Draft BT Internet-Draft BT
Intended status: Standards Track D. Brungard, Ed. Intended status: Standards Track D. Brungard, Ed.
Expires: December 24, 2009 AT&T Expires: February 17, 2010 AT&T
M. Betts, Ed. M. Betts, Ed.
Nortel Networks Huawei Technologies
N. Sprecher N. Sprecher
Nokia Siemens Networks Nokia Siemens Networks
S. Ueno S. Ueno
NTT NTT
June 22, 2009 August 16, 2009
MPLS-TP Requirements MPLS-TP Requirements
draft-ietf-mpls-tp-requirements-09 draft-ietf-mpls-tp-requirements-10
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 24, 2009. This Internet-Draft will expire on February 17, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . 6 1.1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . 6
1.1.2. Definitions . . . . . . . . . . . . . . . . . . . . . 8 1.1.2. Definitions . . . . . . . . . . . . . . . . . . . . . 8
1.2. Transport network overview . . . . . . . . . . . . . . . . 11 1.2. Transport network overview . . . . . . . . . . . . . . . . 11
1.3. Layer network overview . . . . . . . . . . . . . . . . . . 12 1.3. Layer network overview . . . . . . . . . . . . . . . . . . 12
2. MPLS-TP Requirements . . . . . . . . . . . . . . . . . . . . . 13 2. MPLS-TP Requirements . . . . . . . . . . . . . . . . . . . . . 13
2.1. General requirements . . . . . . . . . . . . . . . . . . . 13 2.1. General requirements . . . . . . . . . . . . . . . . . . . 13
2.2. Layering requirements . . . . . . . . . . . . . . . . . . 16 2.2. Layering requirements . . . . . . . . . . . . . . . . . . 16
2.3. Data plane requirements . . . . . . . . . . . . . . . . . 17 2.3. Data plane requirements . . . . . . . . . . . . . . . . . 17
2.4. Control plane requirements . . . . . . . . . . . . . . . . 18 2.4. Control plane requirements . . . . . . . . . . . . . . . . 18
2.5. Network Management requirements . . . . . . . . . . . . . 20 2.5. Recovery requirements . . . . . . . . . . . . . . . . . . 19
2.6. Operation, Administration and Maintenance (OAM) 2.5.1. Data plane behavior requirements . . . . . . . . . . . 20
requirements . . . . . . . . . . . . . . . . . . . . . . . 20 2.5.1.1. Protection . . . . . . . . . . . . . . . . . . . . 21
2.7. Network performance monitoring requirements . . . . . . . 20 2.5.1.2. Sharing of protection resources . . . . . . . . . 22
2.8. Recovery requirements . . . . . . . . . . . . . . . . . . 20 2.5.2. Restoration . . . . . . . . . . . . . . . . . . . . . 22
2.8.1. Data plane behavior requirements . . . . . . . . . . . 21 2.5.3. Triggers for protection, restoration, and reversion . 22
2.8.1.1. Protection . . . . . . . . . . . . . . . . . . . . 21 2.5.4. Management plane operation of protection and
2.8.1.2. Sharing of protection resources . . . . . . . . . 22
2.8.2. Restoration . . . . . . . . . . . . . . . . . . . . . 22
2.8.3. Triggers for protection, restoration, and reversion . 23
2.8.4. Management plane operation of protection and
restoration . . . . . . . . . . . . . . . . . . . . . 23 restoration . . . . . . . . . . . . . . . . . . . . . 23
2.8.5. Control plane and in-band OAM operation of recovery . 24 2.5.5. Control plane and in-band OAM operation of recovery . 24
2.8.6. Topology-specific recovery mechanisms . . . . . . . . 25 2.5.6. Topology-specific recovery mechanisms . . . . . . . . 24
2.8.6.1. Ring protection . . . . . . . . . . . . . . . . . 25 2.5.6.1. Ring protection . . . . . . . . . . . . . . . . . 24
2.9. QoS requirements . . . . . . . . . . . . . . . . . . . . . 28 2.6. QoS requirements . . . . . . . . . . . . . . . . . . . . . 27
2.10. Security requirements . . . . . . . . . . . . . . . . . . 28 3. Requirements Discussed in Other Documents . . . . . . . . . . 28
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 3.1. Network Management requirements . . . . . . . . . . . . . 28
4. Security Considerations . . . . . . . . . . . . . . . . . . . 28 3.2. Operation, Administration and Maintenance (OAM)
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29 requirements . . . . . . . . . . . . . . . . . . . . . . . 28
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.3. Network performance monitoring requirements . . . . . . . 28
6.1. Normative References . . . . . . . . . . . . . . . . . . . 29 3.4. Security requirements . . . . . . . . . . . . . . . . . . 28
6.2. Informative References . . . . . . . . . . . . . . . . . . 30 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
5. Security Considerations . . . . . . . . . . . . . . . . . . . 29
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.1. Normative References . . . . . . . . . . . . . . . . . . . 29
7.2. Informative References . . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
Bandwidth demand continues to grow worldwide, stimulated by the Bandwidth demand continues to grow worldwide, stimulated by the
accelerating growth and penetration of new packet based services and accelerating growth and penetration of new packet based services and
multimedia applications: multimedia applications:
o Packet-based services such as Ethernet, Voice over IP (VoIP), o Packet-based services such as Ethernet, Voice over IP (VoIP),
Layer 2 (L2)/Layer 3 (L3) Virtual Private Networks (VPNs), IP Layer 2 (L2)/Layer 3 (L3) Virtual Private Networks (VPNs), IP
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and it is already playing an important role in transport networks and and it is already playing an important role in transport networks and
services. However, not all of MPLS's capabilities and mechanisms are services. However, not all of MPLS's capabilities and mechanisms are
needed and/or consistent with transport network operations. There needed and/or consistent with transport network operations. There
are also transport technology characteristics that are not currently are also transport technology characteristics that are not currently
reflected in MPLS. There is therefore the need to define an MPLS reflected in MPLS. There is therefore the need to define an MPLS
Transport Profile (MPLS-TP) that supports the capabilities and Transport Profile (MPLS-TP) that supports the capabilities and
functionalities needed for packet transport network services and functionalities needed for packet transport network services and
operations through combining the packet experience of MPLS with the operations through combining the packet experience of MPLS with the
operational experience and practices of existing transport networks. operational experience and practices of existing transport networks.
MPLS-TP will enable the depoyment of packet based transport networks MPLS-TP will enable the deployment of packet based transport networks
that will efficiently scale to support packet services in a simple that will efficiently scale to support packet services in a simple
and cost effective way. MPLS-TP needs to combine the necessary and cost effective way. MPLS-TP needs to combine the necessary
existing capabilities of MPLS with additional minimal mechanisms in existing capabilities of MPLS with additional minimal mechanisms in
order that it can be used in a transport role. order that it can be used in a transport role.
This document specifies the requirements of an MPLS Transport Profile This document specifies the requirements of an MPLS Transport Profile
(MPLS-TP). The requirements are for the behavior of the protocol (MPLS-TP). The requirements are for the behavior of the protocol
mechanisms and procedures that constitute building blocks out of mechanisms and procedures that constitute building blocks out of
which the MPLS transport profile is constructed. That is, the which the MPLS transport profile is constructed. That is, the
requirements indicate what features are to be available in the MPLS requirements indicate what features are to be available in the MPLS
toolkit for use by MPLS-TP. The requirements in this document do not toolkit for use by MPLS-TP. The requirements in this document do not
describe what functions an MPLS-TP implementation supports. The describe what functions an MPLS-TP implementation supports. The
purpose of this document is to identify the toolkit and any new purpose of this document is to identify the toolkit and any new
protocol work that is required. protocol work that is required.
Although this document is not a protocol specification, the key words
"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are used as
described in [RFC2119] and are to be interpreted as instructions to
the protocol designers producing solutions that satisfy the
requirements set out in this document.
This document is a product of a joint ITU-T and IETF effort to This document is a product of a joint ITU-T and IETF effort to
include an MPLS Transport Profile within the IETF MPLS and PWE3 include an MPLS Transport Profile within the IETF MPLS and PWE3
architectures to support the capabilities and functionalities of a architectures to support the capabilities and functionalities of a
packet transport network as defined by ITU-T. packet transport network as defined by ITU-T. The document is a
requirements specification, but is presented on the Standards Track
so that it can be more easily cited as a normative reference from
within the work of the ITU-T.
This work is based on two sources of requirements, MPLS and PWE3 This work is based on two sources of requirements, MPLS and PWE3
architectures as defined by IETF and packet transport networks as architectures as defined by IETF and packet transport networks as
defined by ITU-T. The requirements of MPLS-TP are provided below. defined by ITU-T. The requirements of MPLS-TP are provided below.
The relevant functions of MPLS and PWE3 are included in MPLS-TP, The relevant functions of MPLS and PWE3 are included in MPLS-TP,
except where explicitly excluded. except where explicitly excluded. Any new functionality that is
defined to fulfill the requirements for MPLS-TP must be agreed within
the IETF through the IETF consensus process as per [RFC4929].
Although both static and dynamic configuration of MPLS-TP transport MPLS-TP transport paths may be established using static or dynamic
paths (including Operations, Administration and Maintenance (OAM) and configuration. It should be noted that the MPLS-TP network and its
protection capabilities) is required by this document, it MUST be transport paths can always be operated fully (including OAM and
possible for operators to be able to completely operate (including protection capabilities) in the absence of any control plane.
OAM and protection capabilities) an MPLS-TP network in the absence of
any control plane.
1.1. Terminology 1.1. Terminology
Note: Mapping between the terms in this section and ITU-T terminology Note: Mapping between the terms in this section and ITU-T terminology
is described in [I-D.helvoort-mpls-tp-rosetta-stone]. is described in [I-D.helvoort-mpls-tp-rosetta-stone].
The recovery requirements in this document use the recovery The recovery requirements in this document use the recovery
terminology defined in RFC 4427 [RFC4427], this is applied to both terminology defined in RFC 4427 [RFC4427], this is applied to both
control plane and management plane based operations of MPLS-TP control plane and management plane based operations of MPLS-TP
transport paths. transport paths.
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OTN: Optical Transport Network OTN: Optical Transport Network
P2MP: Point to Multi-Point P2MP: Point to Multi-Point
P2P: Point to Point P2P: Point to Point
PDU: Protocol Data Unit PDU: Protocol Data Unit
PSC: Protection State Coordination PSC: Protection State Coordination
PW: Pseudo Wire PW: Pseudowire
QoS: Quality of Service QoS: Quality of Service
SDH: Synchronous Digital Hierarchy SDH: Synchronous Digital Hierarchy
SLA: Service Level Agreement SLA: Service Level Agreement
SLS: Service Level Specification SLS: Service Level Specification
S-PE: Switching Provider Edge S-PE: Switching Provider Edge
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resource reservation involved retain their common elements. These resource reservation involved retain their common elements. These
smaller monitored domains are sublayers. smaller monitored domains are sublayers.
It is sometimes useful to independently control forwarding in a It is sometimes useful to independently control forwarding in a
smaller domain within a layer network but the control of resource smaller domain within a layer network but the control of resource
reservation and OAM retain their common elements. These smaller reservation and OAM retain their common elements. These smaller
domains are partitions of the layer network. domains are partitions of the layer network.
2. MPLS-TP Requirements 2. MPLS-TP Requirements
This document specifies the requirements of an MPLS Transport Profile The MPLS-TP requirements set out in this section are for the behavior
(MPLS-TP). The requirements are for the behavior of the protocol of the protocol mechanisms and procedures that constitute building
mechanisms and procedures that constitute building blocks out of blocks out of which the MPLS transport profile is constructed. That
which the MPLS transport profile is constructed. That is, the is, the requirements indicate what features are to be available in
requirements indicate what features are to be available in the MPLS the MPLS toolkit for use by MPLS-TP.
toolkit for use by MPLS-TP. The requirements in this document do not
describe what functions an MPLS-TP implementation supports. The
purpose of this document is to identify the toolkit and any new
protocol work that is required.
2.1. General requirements 2.1. General requirements
1 The MPLS-TP data plane MUST be a subset of the MPLS data plane as 1 The MPLS-TP data plane MUST be a subset of the MPLS data plane as
defined by the IETF. When MPLS offers multiple options in this defined by the IETF. When MPLS offers multiple options in this
respect, MPLS-TP SHOULD select the minimum sub-set (necessary and respect, MPLS-TP SHOULD select the minimum sub-set (necessary and
sufficient subset) applicable to a transport network application. sufficient subset) applicable to a transport network application.
2 Any new functionality that is defined to fulfill the requirements 2 The MPLS-TP design SHOULD as far as reasonably possible re-use
for MPLS-TP MUST be agreed within the IETF through the IETF
consensus process as per [RFC4929]
3 The MPLS-TP design SHOULD as far as reasonably possible re-use
existing MPLS standards. existing MPLS standards.
4 Mechanisms and capabilities MUST be able to interoperate with 3 Mechanisms and capabilities MUST be able to interoperate with
existing IETF MPLS [RFC3031] and IETF PWE3 [RFC3985] control and existing IETF MPLS [RFC3031] and IETF PWE3 [RFC3985] control and
data planes where appropriate. data planes where appropriate.
A. Data plane interoperability MUST NOT require a gateway A. Data plane interoperability MUST NOT require a gateway
function. function.
5 MPLS-TP and its interfaces, both internal and external, MUST be 4 MPLS-TP and its interfaces, both internal and external, MUST be
sufficiently well-defined that interworking equipment supplied by sufficiently well-defined that interworking equipment supplied by
multiple vendors will be possible both within a single domain, multiple vendors will be possible both within a single domain,
and between domains. and between domains.
6 MPLS-TP MUST be a connection-oriented packet switching technology 5 MPLS-TP MUST be a connection-oriented packet switching technology
with traffic engineering capabilities that allow deterministic with traffic engineering capabilities that allow deterministic
control of the use of network resources. control of the use of network resources.
7 MPLS-TP MUST support traffic engineered point to point (P2P) and 6 MPLS-TP MUST support traffic engineered point to point (P2P) and
point to multipoint (P2MP) transport paths. point to multipoint (P2MP) transport paths.
8 MPLS-TP MUST support unidirectional, co-routed bidirectional and 7 MPLS-TP MUST support unidirectional, co-routed bidirectional and
associated bidirectional point-to-point transport paths. associated bidirectional point-to-point transport paths.
9 MPLS-TP MUST support unidirectional point-to-multipoint transport 8 MPLS-TP MUST support unidirectional point-to-multipoint transport
paths. paths.
10 The end points of a co-routed bidirectional transport path MUST 9 The end points of a co-routed bidirectional transport path MUST
be aware of the pairing relationship of the forward and reverse be aware of the pairing relationship of the forward and reverse
paths used to support the bidirectional service. paths used to support the bidirectional service.
11 All nodes on the path of a co-routed bidirectional transport path 10 All nodes on the path of a co-routed bidirectional transport path
in the same (sub-)layer as the path MUST be aware of the pairing in the same (sub-)layer as the path MUST be aware of the pairing
relationship of the forward and the backward directions of the relationship of the forward and the backward directions of the
transport path. transport path.
12 The end points of an associated bidirectional transport path MUST 11 The end points of an associated bidirectional transport path MUST
be aware of the pairing relationship of the forward and reverse be aware of the pairing relationship of the forward and reverse
paths used to support the bidirectional service. paths used to support the bidirectional service.
13 Nodes on the path of an associated bidirectional transport path 12 Nodes on the path of an associated bidirectional transport path
where both the forward and backward directions transit the same where both the forward and backward directions transit the same
node in the same (sub-)layer as the path SHOULD be aware of the node in the same (sub-)layer as the path SHOULD be aware of the
pairing relationship of the forward and the backward directions pairing relationship of the forward and the backward directions
of the transport path. of the transport path.
14 MPLS-TP MUST support bidirectional transport paths with symmetric 13 MPLS-TP MUST support bidirectional transport paths with symmetric
bandwidth requirements, i.e. the amount of reserved bandwidth is bandwidth requirements, i.e. the amount of reserved bandwidth is
the same between the forward and backward directions. the same between the forward and backward directions.
15 MPLS-TP MUST support bidirectional transport paths with 14 MPLS-TP MUST support bidirectional transport paths with
asymmetric bandwidth requirements, i.e. the amount of reserved asymmetric bandwidth requirements, i.e. the amount of reserved
bandwidth differs between the forward and backward directions. bandwidth differs between the forward and backward directions.
16 MPLS-TP MUST support the logical separation of the control and 15 MPLS-TP MUST support the logical separation of the control and
management planes from the data plane. management planes from the data plane.
17 MPLS-TP MUST support the physical separation of the control and 16 MPLS-TP MUST support the physical separation of the control and
management planes from the data plane. management planes from the data plane. That is, it must be
possible to operate the control and management planes out-of-band
and no assumptions should be made about the state of the data
plane channels from information about the control or management
plane channels when they are running out-of-band.
18 MPLS-TP MUST support static provisioning of transport paths via 17 MPLS-TP MUST support static provisioning of transport paths via
the management plane. the management plane.
19 A solution MUST be defined to support dynamic provisioning and 18 A solution MUST be defined to support dynamic provisioning and
restoration of MPLS-TP transport paths via a control plane. restoration of MPLS-TP transport paths via a control plane.
20 Static provisioning MUST NOT depend on the presence of any 19 Static provisioning MUST NOT depend on the presence of any
element of a control plane. element of a control plane.
21 MPLS-TP MUST support the co-existence of statically and 20 MPLS-TP MUST support the co-existence of statically and
dynamically provisioned/managed MPLS-TP transport paths within dynamically provisioned/managed MPLS-TP transport paths within
the same layer network or domain. the same layer network or domain.
22 Mechanisms in an MPLS-TP layer network that satisfy functional 21 Mechanisms in an MPLS-TP layer network that satisfy functional
requirements that are common to general transport layer networks requirements that are common to general transport layer networks
(i.e., independent of technology) SHOULD be operable in a way (i.e., independent of technology) SHOULD be operable in a way
that is similar to the way the equivalent mechanisms are operated that is similar to the way the equivalent mechanisms are operated
in other transport layer technologies. in other transport layer technologies.
23 MPLS-TP MUST support the capability for network operation 22 MPLS-TP MUST support the capability for network operation via the
(including OAM and recovery) via the management plane (without management plane (without the use of any control plane
the use of any control plane protocols). protocols). This includes the configuration and control of OAM
and recovery functions.
24 The MPLS-TP data plane MUST be capable of 23 The MPLS-TP data plane MUST be capable of
A. forwarding data independent of the control or management A. forwarding data independent of the control or management
plane used to configure and operate the MPLS-TP layer plane used to configure and operate the MPLS-TP layer
network. network.
B. taking recovery actions independent of the control or B. taking recovery actions independent of the control or
management plane used to configure the MPLS-TP layer network. management plane used to configure the MPLS-TP layer network.
C. operating normally (i.e. forwarding, OAM and protection MUST C. operating normally (i.e. forwarding, OAM and protection MUST
continue to operate) if the management plane or control plane continue to operate) if the management plane or control plane
that configured the transport paths fails. that configured the transport paths fails.
25 MPLS-TP MUST support mechanisms to avoid or minimize traffic 24 MPLS-TP MUST support mechanisms to avoid or minimize traffic
impact (e.g. packet delay, reordering and loss) during network impact (e.g. packet delay, reordering and loss) during network
reconfiguration. reconfiguration.
26 MPLS-TP MUST support transport paths through multiple homogeneous 25 MPLS-TP MUST support transport paths through multiple homogeneous
domains. domains.
27 MPLS-TP SHOULD support transport paths through multiple non- 26 MPLS-TP SHOULD support transport paths through multiple non-
homogeneous domains. homogeneous domains.
28 MPLS-TP MUST NOT dictate the deployment of any particular network 27 MPLS-TP MUST NOT dictate the deployment of any particular network
topology either physical or logical, however: topology either physical or logical, however:
A. It MUST be possible to deploy MPLS-TP in rings. A. It MUST be possible to deploy MPLS-TP in rings.
B. It MUST be possible to deploy MPLS-TP in arbitrarily B. It MUST be possible to deploy MPLS-TP in arbitrarily
interconnected rings with one or two points of interconnected rings with one or two points of
interconnection. interconnection.
C. MPLS-TP MUST support rings of at least 16 nodes in order to C. MPLS-TP MUST support rings of at least 16 nodes in order to
support the upgrade of existing TDM rings to MPLS-TP. support the upgrade of existing TDM rings to MPLS-TP.
MPLS-TP SHOULD support rings with more than 16 nodes. MPLS-TP SHOULD support rings with more than 16 nodes.
29 MPLS-TP MUST be able to scale at least as well as existing 28 MPLS-TP MUST be able to scale at least as well as existing
transport technologies with growing and increasingly complex transport technologies with growing and increasingly complex
network topologies as well as with increasing bandwidth demands, network topologies as well as with increasing bandwidth demands,
number of customers, and number of services. number of customers, and number of services.
30 MPLS-TP SHOULD support mechanisms to safeguard against the 29 MPLS-TP SHOULD support mechanisms to safeguard against the
provisioning of transport paths which contain forwarding loops. provisioning of transport paths which contain forwarding loops.
2.2. Layering requirements 2.2. Layering requirements
31 A generic and extensible solution MUST be provided to support the 30 A generic and extensible solution MUST be provided to support the
transport of one or more client layer networks (e.g. MPLS-TP, transport of one or more client layer networks (e.g. MPLS-TP,
IP, MPLS, Ethernet, ATM, FR, etc.) over an MPLS-TP layer network. IP, MPLS, Ethernet, ATM, FR, etc.) over an MPLS-TP layer network.
32 A generic and extensible solution MUST be provided to support the 31 A generic and extensible solution MUST be provided to support the
transport of MPLS-TP transport paths over one or more server transport of MPLS-TP transport paths over one or more server
layer networks (such as MPLS-TP, Ethernet, SONET/SDH, OTN, etc.). layer networks (such as MPLS-TP, Ethernet, SONET/SDH, OTN, etc.).
Requirements for bandwidth management within a server layer Requirements for bandwidth management within a server layer
network are outside the scope of this document. network are outside the scope of this document.
33 In an environment where an MPLS-TP layer network is supporting a 32 In an environment where an MPLS-TP layer network is supporting a
client layer network, and the MPLS-TP layer network is supported client layer network, and the MPLS-TP layer network is supported
by a server layer network then operation of the MPLS-TP layer by a server layer network then operation of the MPLS-TP layer
network MUST be possible without any dependencies on the server network MUST be possible without any dependencies on the server
or client layer network. or client layer network.
A. The server layer MUST guarantee that the traffic loading A. The server layer MUST guarantee that the traffic loading
imposed by other clients does not cause the transport service imposed by other clients does not cause the transport service
provided to the MPLS-TP layer to fall below the agreed level. provided to the MPLS-TP layer to fall below the agreed level.
Mechanisms to achieve this are outside the scope of these Mechanisms to achieve this are outside the scope of these
requirements. requirements.
B. It MUST be possible to isolate the control and management B. It MUST be possible to isolate the control and management
planes of the MPLS-TP layer network from the control and planes of the MPLS-TP layer network from the control and
management planes of the client and server layer networks. management planes of the client and server layer networks.
34 A solution MUST be provided to support the transport of a client 33 A solution MUST be provided to support the transport of a client
MPLS or MPLS-TP layer network over a server MPLS or MPLS-TP layer MPLS or MPLS-TP layer network over a server MPLS or MPLS-TP layer
network. network.
A. The level of co-ordination required between the client and A. The level of co-ordination required between the client and
server MPLS(-TP) layer networks MUST be minimized (preferably server MPLS(-TP) layer networks MUST be minimized (preferably
no co-ordination will be required). no co-ordination will be required).
B. The MPLS(-TP) server layer network MUST be capable of B. The MPLS(-TP) server layer network MUST be capable of
transporting the complete set of packets generated by the transporting the complete set of packets generated by the
client MPLS(-TP) layer network, which may contain packets client MPLS(-TP) layer network, which may contain packets
that are not MPLS packets (e.g. IP or CNLS packets used by that are not MPLS packets (e.g. IP or CNLS packets used by
the control/management plane of the client MPLS(-TP) layer the control/management plane of the client MPLS(-TP) layer
network). network).
35 It MUST be possible to operate the layers of a multi-layer 34 It MUST be possible to operate the layers of a multi-layer
network that includes an MPLS-TP layer autonomously. network that includes an MPLS-TP layer autonomously.
The above are not only technology requirements, but also operational The above are not only technology requirements, but also operational
requirements. Different administrative groups may be responsible for requirements. Different administrative groups may be responsible for
the same layer network or different layer networks. the same layer network or different layer networks.
36 It MUST be possible to hide MPLS-TP layer network addressing and 35 It MUST be possible to hide MPLS-TP layer network addressing and
other information (e.g. topology) from client layer networks. other information (e.g. topology) from client layer networks.
However, it SHOULD be possible, at the option of the operator, to However, it SHOULD be possible, at the option of the operator, to
leak a limited amount of summarized information (such as SRLGs or leak a limited amount of summarized information (such as SRLGs or
reachability) between layers. reachability) between layers.
2.3. Data plane requirements 2.3. Data plane requirements
37 It MUST be possible to operate and configure the MPLS-TP data 36 It MUST be possible to operate and configure the MPLS-TP data
plane without any IP forwarding capability in the MPLS-TP data plane without any IP forwarding capability in the MPLS-TP data
plane. i.e. the data plane only operates on the MPLS label. plane. i.e. the data plane only operates on the MPLS label.
38 It MUST be possible for the end points of an MPLS-TP transport 37 It MUST be possible for the end points of an MPLS-TP transport
path that is carrying an aggregate of client transport paths to path that is carrying an aggregate of client transport paths to
be able to decompose the aggregate transport path into its be able to decompose the aggregate transport path into its
component client transport paths. component client transport paths.
39 A transport path on a link MUST be uniquely identifiable by a 38 A transport path on a link MUST be uniquely identifiable by a
single label on that link. single label on that link.
40 A transport path's source MUST be identifiable at its destination 39 A transport path's source MUST be identifiable at its destination
within its layer network. within its layer network.
41 MPLS-TP MUST be capable of using P2MP server (sub-)layer 40 MPLS-TP MUST be capable of using P2MP server (sub-)layer
capabilities as well as P2P server (sub-)layer capabilities when capabilities as well as P2P server (sub-)layer capabilities when
supporting P2MP MPLS-TP transport paths. supporting P2MP MPLS-TP transport paths.
42 MPLS-TP MUST be extensible in order to accommodate new types of 41 MPLS-TP MUST be extensible in order to accommodate new types of
client layer networks and services. client layer networks and services.
43 MPLS-TP SHOULD support mechanisms to enable the reserved 42 MPLS-TP SHOULD support mechanisms to enable the reserved
bandwidth associated with a transport path to be increased bandwidth associated with a transport path to be increased
without impacting the existing traffic on that transport path without impacting the existing traffic on that transport path
provided enough resources are available. provided enough resources are available.
44 MPLS-TP SHOULD support mechanisms to enable the reserved 43 MPLS-TP SHOULD support mechanisms to enable the reserved
bandwidth of a transport path to be decreased without impacting bandwidth of a transport path to be decreased without impacting
the existing traffic on that transport path, provided that the the existing traffic on that transport path, provided that the
level of existing traffic is smaller than the reserved bandwidth level of existing traffic is smaller than the reserved bandwidth
following the decrease. following the decrease.
45 MPLS-TP MUST support mechanisms which ensure the integrity of the 44 MPLS-TP MUST support mechanisms which ensure the integrity of the
transported customer's service traffic as required by its transported customer's service traffic as required by its
associated SLA. Loss of integrity may be defined as packet associated SLA. Loss of integrity may be defined as packet
corruption, re-ordering or loss during normal network conditions. corruption, re-ordering or loss during normal network conditions.
46 MPLS-TP MUST support mechanisms to detect when loss of integrity 45 MPLS-TP MUST support mechanisms to detect when loss of integrity
of the transported customer's service traffic has occurred. of the transported customer's service traffic has occurred.
47 MPLS-TP MUST support an unambiguous and reliable means of 46 MPLS-TP MUST support an unambiguous and reliable means of
distinguishing users' (client) packets from MPLS-TP control distinguishing users' (client) packets from MPLS-TP control
packets (e.g. control plane, management plane, OAM and protection packets (e.g. control plane, management plane, OAM and protection
switching packets). switching packets).
2.4. Control plane requirements 2.4. Control plane requirements
This section defines the requirements that apply to an MPLS-TP This section defines the requirements that apply to an MPLS-TP
control plane. Note that it MUST be possible to operate an MPLS-TP control plane. Note that it MUST be possible to operate an MPLS-TP
network without using a control plane. network without using a control plane.
The ITU-T has defined an architecture for Automatically Switched The ITU-T has defined an architecture for Automatically Switched
Optical Networks (ASON) in G.8080 [ITU.G8080.2006] and G.8080 Amd1 Optical Networks (ASON) in G.8080 [ITU.G8080.2006] and G.8080 Amd1
[ITU.G8080.2008]. The control plane for MPLS-TP MUST fit within the [ITU.G8080.2008]. The control plane for MPLS-TP MUST fit within the
ASON architecture. ASON architecture.
An interpretation of the ASON signaling and routing requirements in An interpretation of the ASON signaling and routing requirements in
the context of GMPLS can be found in [RFC4139] and [RFC4258]. the context of GMPLS can be found in [RFC4139] and [RFC4258].
Additionally: Additionally:
48 The MPLS-TP control plane MUST support control plane topology and 47 The MPLS-TP control plane MUST support control plane topology and
data plane topology independence. As a consequence a failure of data plane topology independence. As a consequence a failure of
the control plane does not imply that there has also been a the control plane does not imply that there has also been a
failure of the data plane. failure of the data plane.
49 The MPLS-TP control plane MUST be able to be operated independent 48 The MPLS-TP control plane MUST be able to be operated independent
of any particular client or server layer control plane. of any particular client or server layer control plane.
50 MPLS-TP SHOULD define a solution to support an integrated control 49 MPLS-TP SHOULD define a solution to support an integrated control
plane encompassing MPLS-TP together with its server and client plane encompassing MPLS-TP together with its server and client
layer networks when these layer networks belong to the same layer networks when these layer networks belong to the same
administrative domain. administrative domain.
51 The MPLS-TP control plane MUST support establishing all the 50 The MPLS-TP control plane MUST support establishing all the
connectivity patterns defined for the MPLS-TP data plane (i.e., connectivity patterns defined for the MPLS-TP data plane (i.e.,
unidirectional P2P, associated bidirectional P2P, co-routed unidirectional P2P, associated bidirectional P2P, co-routed
bidirectional P2P, unidirectional P2MP) including configuration bidirectional P2P, unidirectional P2MP) including configuration
of protection functions and any associated maintenance functions. of protection functions and any associated maintenance functions.
52 The MPLS-TP control plane MUST support the configuration and 51 The MPLS-TP control plane MUST support the configuration and
modification of OAM maintenance points as well as the activation/ modification of OAM maintenance points as well as the activation/
deactivation of OAM when the transport path or transport service deactivation of OAM when the transport path or transport service
is established or modified. is established or modified.
53 An MPLS-TP control plane MUST support operation of the recovery 52 An MPLS-TP control plane MUST support operation of the recovery
functions described in Section 2.8. functions described in Section 2.8.
54 An MPLS-TP control plane MUST scale gracefully to support a large 53 An MPLS-TP control plane MUST scale gracefully to support a large
number of transport paths, nodes and links. number of transport paths, nodes and links.
55 If a control plane is used for MPLS-TP, following a control plane 54 If a control plane is used for MPLS-TP, following a control plane
failure, the control plane MUST be capable of restarting and failure, the control plane MUST be capable of restarting and
relearning its previous state without impacting forwarding. relearning its previous state without impacting forwarding.
56 An MPLS-TP control plane MUST provide a mechanism for dynamic 55 An MPLS-TP control plane MUST provide a mechanism for dynamic
ownership transfer of the control of MPLS-TP transport paths from ownership transfer of the control of MPLS-TP transport paths from
the management plane to the control plane and vice versa. The the management plane to the control plane and vice versa. The
number of reconfigurations required in the data plane MUST be number of reconfigurations required in the data plane MUST be
minimized (preferably no data plane reconfiguration will be minimized (preferably no data plane reconfiguration will be
required). required).
2.5. Network Management requirements 2.5. Recovery requirements
For requirements related to network management functionality
(Management Plane in ITU-T terminology) for MPLS-TP, see the MPLS-TP
Network Management requirements document [I-D.ietf-mpls-tp-nm-req].
2.6. Operation, Administration and Maintenance (OAM) requirements
For requirements related to OAM functionality for MPLS-TP, see the
MPLS-TP OAM requirements document
[I-D.ietf-mpls-tp-oam-requirements].
2.7. Network performance monitoring requirements
For requirements related to performance monitoring functionality for
MPLS-TP, see the MPLS-TP OAM requirements document
[I-D.ietf-mpls-tp-oam-requirements].
2.8. Recovery requirements
Network survivability plays a critical role in the delivery of Network survivability plays a critical role in the delivery of
reliable services. Network availability is a significant contributor reliable services. Network availability is a significant contributor
to revenue and profit. Service guarantees in the form of SLAs to revenue and profit. Service guarantees in the form of SLAs
require a resilient network that rapidly detects facility or node require a resilient network that rapidly detects facility or node
failures and restores network operation in accordance with the terms failures and restores network operation in accordance with the terms
of the SLA. of the SLA.
57 MPLS-TP MUST provide protection and restoration mechanisms. 56 MPLS-TP MUST provide protection and restoration mechanisms.
A. MPLS-TP recovery techniques SHOULD be identical (or as A. MPLS-TP recovery techniques SHOULD be identical (or as
similar as possible) to those already used in existing similar as possible) to those already used in existing
transport networks to simplify implementation and operations. transport networks to simplify implementation and operations.
However, this MUST NOT override any other requirement. However, this MUST NOT override any other requirement.
B. Recovery techniques used for P2P and P2MP SHOULD be identical B. Recovery techniques used for P2P and P2MP SHOULD be identical
to simplify implementation and operation. However, this MUST to simplify implementation and operation. However, this MUST
NOT override any other requirement. NOT override any other requirement.
58 MPLS-TP recovery mechanisms MUST be applicable at various levels 57 MPLS-TP recovery mechanisms MUST be applicable at various levels
throughout the network including support for link, transport throughout the network including support for link, transport
path, segment, concatenated segment and end to end recovery. path, segment, concatenated segment and end to end recovery.
59 MPLS-TP recovery paths MUST meet the SLA protection objectives of 58 MPLS-TP recovery paths MUST meet the SLA protection objectives of
the service. the service.
A. MPLS-TP MUST provide mechanisms to guarantee 50ms recovery A. MPLS-TP MUST provide mechanisms to guarantee 50ms recovery
times from the moment of fault detection in networks with times from the moment of fault detection in networks with
spans less than 1200 km. spans less than 1200 km.
B. For protection it MUST be possible to require protection of B. For protection it MUST be possible to require protection of
100% of the traffic on the protected path. 100% of the traffic on the protected path.
C. Recovery MUST meet SLA requirements over multiple domains. C. Recovery MUST meet SLA requirements over multiple domains.
60 Recovery objectives SHOULD be configurable per transport path. 59 Recovery objectives SHOULD be configurable per transport path.
61 The recovery mechanisms SHOULD be applicable to any topology. 60 The recovery mechanisms SHOULD be applicable to any topology.
62 The recovery mechanisms MUST support the means to operate in 61 The recovery mechanisms MUST support the means to operate in
synergy with (including coordination of timing) the recovery synergy with (including coordination of timing) the recovery
mechanisms present in any client or server transport networks mechanisms present in any client or server transport networks
(for example, Ethernet, SDH, OTN, WDM) to avoid race conditions (for example, Ethernet, SDH, OTN, WDM) to avoid race conditions
between the layers. between the layers.
63 MPLS-TP recovery and reversion mechanisms MUST prevent frequent 62 MPLS-TP recovery and reversion mechanisms MUST prevent frequent
operation of recovery in the event of an intermittent defect. operation of recovery in the event of an intermittent defect.
2.8.1. Data plane behavior requirements 2.5.1. Data plane behavior requirements
General protection and survivability requirements are expressed in General protection and survivability requirements are expressed in
terms of the behavior in the data plane. terms of the behavior in the data plane.
2.8.1.1. Protection 2.5.1.1. Protection
Note: Only nodes that are aware of the pairing relationship between Note: Only nodes that are aware of the pairing relationship between
the forward and backward directions of an associated bidirectional the forward and backward directions of an associated bidirectional
transport path can be used as end points to protect all or part of transport path can be used as end points to protect all or part of
that transport path. that transport path.
64 It MUST be possible to provide protection for the MPLS-TP data 63 It MUST be possible to provide protection for the MPLS-TP data
plane without any IP forwarding capability in the MPLS-TP data plane without any IP forwarding capability in the MPLS-TP data
plane. i.e. the data plane only operates on the MPLS label. plane. i.e. the data plane only operates on the MPLS label.
65 MPLS-TP protection mechanisms MUST support revertive and non- 64 MPLS-TP protection mechanisms MUST support revertive and non-
revertive behavior. revertive behavior.
66 MPLS-TP MUST support 1+1 protection. 65 MPLS-TP MUST support 1+1 protection.
A. Bidirectional 1+1 protection for P2P connectivity MUST be A. Bidirectional 1+1 protection for P2P connectivity MUST be
supported. supported.
B. Unidirectional 1+1 protection for P2P connectivity MUST be B. Unidirectional 1+1 protection for P2P connectivity MUST be
supported. supported.
C. Unidirectional 1+1 protection for P2MP connectivity MUST be C. Unidirectional 1+1 protection for P2MP connectivity MUST be
supported. supported.
67 MPLS-TP MUST support the ability to share protection resources 66 MPLS-TP MUST support the ability to share protection resources
amongst a number of transport paths. amongst a number of transport paths.
68 MPLS-TP MUST support 1:n protection (including 1:1 protection). 67 MPLS-TP MUST support 1:n protection (including 1:1 protection).
A. Bidirectional 1:n protection for P2P connectivity MUST be A. Bidirectional 1:n protection for P2P connectivity MUST be
supported, and SHOULD be the default behavior for 1:n supported, and SHOULD be the default behavior for 1:n
protection. protection.
B. Unidirectional 1:n protection for P2MP connectivity MUST be B. Unidirectional 1:n protection for P2MP connectivity MUST be
supported. supported.
C. Unidirectional 1:n protection for P2P connectivity is not C. Unidirectional 1:n protection for P2P connectivity is not
required and MAY be omitted from the MPLS-TP specifications. required and MAY be omitted from the MPLS-TP specifications.
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D. The action of protection switching MUST NOT cause the user D. The action of protection switching MUST NOT cause the user
data to enter an uncontrolled loop. The protection switching data to enter an uncontrolled loop. The protection switching
system MAY cause traffic to pass over a given link more than system MAY cause traffic to pass over a given link more than
once, but it must do so in a controlled way such that once, but it must do so in a controlled way such that
uncontrolled loops do not form. uncontrolled loops do not form.
Note: Support for extra traffic (as defined in [RFC4427]) is not Note: Support for extra traffic (as defined in [RFC4427]) is not
required in MPLS-TP and MAY be omitted from the MPLS-TP required in MPLS-TP and MAY be omitted from the MPLS-TP
specifications. specifications.
2.8.1.2. Sharing of protection resources 2.5.1.2. Sharing of protection resources
69 MPLS-TP SHOULD support 1:n (including 1:1) shared mesh recovery. 68 MPLS-TP SHOULD support 1:n (including 1:1) shared mesh recovery.
70 MPLS-TP MUST support sharing of protection resources such that 69 MPLS-TP MUST support sharing of protection resources such that
protection paths that are known not to be required concurrently protection paths that are known not to be required concurrently
can share the same resources. can share the same resources.
2.8.2. Restoration 2.5.2. Restoration
71 The restoration transport path MUST be able to share resources 70 The restoration transport path MUST be able to share resources
with the transport path being replaced (sometimes known as soft with the transport path being replaced (sometimes known as soft
rerouting). rerouting).
72 Restoration priority MUST be supported so that an implementation 71 Restoration priority MUST be supported so that an implementation
can determine the order in which transport paths should be can determine the order in which transport paths should be
restored (to minimize service restoration time as well as to gain restored (to minimize service restoration time as well as to gain
access to available spare capacity on the best paths). access to available spare capacity on the best paths).
73 Preemption priority MUST be supported to allow restoration to 72 Preemption priority MUST be supported to allow restoration to
displace other transport paths in the event of resource displace other transport paths in the event of resource
constraint. constraint.
74 MPLS-TP restoration mechanisms MUST support revertive and non- 73 MPLS-TP restoration mechanisms MUST support revertive and non-
revertive behavior. revertive behavior.
2.8.3. Triggers for protection, restoration, and reversion 2.5.3. Triggers for protection, restoration, and reversion
Recovery actions may be triggered from different places as follows: Recovery actions may be triggered from different places as follows:
75 MPLS-TP MUST support physical layer fault indication triggers. 74 MPLS-TP MUST support fault indication triggers from lower layers.
This includes faults detected and reported by lower layer
protocols, and faults reported directly by the physical medium
(for example, loss of light).
76 MPLS-TP MUST support OAM-based triggers. 75 MPLS-TP MUST support OAM-based triggers.
77 MPLS-TP MUST support management plane triggers (e.g., forced 76 MPLS-TP MUST support management plane triggers (e.g., forced
switch, etc.). switch, etc.).
78 There MUST be a mechanism to allow administrative recovery 77 There MUST be a mechanism to allow administrative recovery
actions to be distinguished from recovery actions initiated by actions to be distinguished from recovery actions initiated by
other triggers. other triggers.
79 Where a control plane is present, MPLS-TP SHOULD support control 78 Where a control plane is present, MPLS-TP SHOULD support control
plane restoration triggers. plane restoration triggers.
80 MPLS-TP protection mechanisms MUST support priority logic to 79 MPLS-TP protection mechanisms MUST support priority logic to
negotiate and accommodate coexisting requests (i.e., multiple negotiate and accommodate coexisting requests (i.e., multiple
requests) for protection switching (e.g., administrative requests requests) for protection switching (e.g., administrative requests
and requests due to link/node failures). and requests due to link/node failures).
2.8.4. Management plane operation of protection and restoration 2.5.4. Management plane operation of protection and restoration
All functions described here are for control by the operator. All functions described here are for control by the operator.
81 It MUST be possible to configure protection paths and protection- 80 It MUST be possible to configure protection paths and protection-
to-working path relationships (sometimes known as protection to-working path relationships (sometimes known as protection
groups). groups).
82 There MUST be support for pre-calculation of recovery paths. 81 There MUST be support for pre-calculation of recovery paths.
83 There MUST be support for pre-provisioning of recovery paths. 82 There MUST be support for pre-provisioning of recovery paths.
84 The external controls as defined in [RFC4427] MUST be supported. 83 The external controls as defined in [RFC4427] MUST be supported.
A. External controls overruled by higher priority requests A. External controls overruled by higher priority requests
(e.g., administrative requests and requests due to link/node (e.g., administrative requests and requests due to link/node
failures) or unable to be signaled to the remote end (e.g. failures) or unable to be signaled to the remote end (e.g.
because of a protection state coordination fail) MUST be because of a protection state coordination fail) MUST be
dropped. dropped.
85 It MUST be possible to test and validate any protection/ 84 It MUST be possible to test and validate any protection/
restoration mechanisms and protocols: restoration mechanisms and protocols:
A. Including the integrity of the protection/recovery transport A. Including the integrity of the protection/recovery transport
path. path.
B. Without triggering the actual protection/restoration. B. Without triggering the actual protection/restoration.
C. While the working path is in service. C. While the working path is in service.
D. While the working path is out of service. D. While the working path is out of service.
86 Restoration resources MAY be pre-planned and selected a priori, 85 Restoration resources MAY be pre-planned and selected a priori,
or computed after failure occurrence. or computed after failure occurrence.
87 When preemption is supported for restoration purposes, it MUST be 86 When preemption is supported for restoration purposes, it MUST be
possible for the operator to configure it. possible for the operator to configure it.
88 The management plane MUST provide indications of protection 87 The management plane MUST provide indications of protection
events and triggers. events and triggers.
89 The management plane MUST allow the current protection status of 88 The management plane MUST allow the current protection status of
all transport paths to be determined. all transport paths to be determined.
2.8.5. Control plane and in-band OAM operation of recovery 2.5.5. Control plane and in-band OAM operation of recovery
90 The MPLS-TP control plane (which is not mandatory in an MPLS-TP 89 The MPLS-TP control plane (which is not mandatory in an MPLS-TP
implementation) MUST be capable of supporting: implementation) MUST be capable of supporting:
A. establishment and maintenance of all recovery entities and A. establishment and maintenance of all recovery entities and
functions functions
B. signaling of administrative control B. signaling of administrative control
C. protection state coordination (PSC). Since control plane C. protection state coordination (PSC). Since control plane
network topology is independent from the data plane network network topology is independent from the data plane network
topology, the PSC supported by the MPLS-TP control plane MAY topology, the PSC supported by the MPLS-TP control plane MAY
run on resources different than the data plane resources run on resources different than the data plane resources
handled within the recovery mechanism (e.g. backup). handled within the recovery mechanism (e.g. backup).
91 In-band OAM MUST be capable of supporting: 90 In-band OAM MUST be capable of supporting:
A. signaling of administrative control A. signaling of administrative control
B. protection state coordination (PSC). Since in-band OAM tools B. protection state coordination (PSC). Since in-band OAM tools
share the data plane with the carried transport service, in share the data plane with the carried transport service, in
order to optimize the usage of network resources, the PSC order to optimize the usage of network resources, the PSC
supported by in-band OAM MUST run on protection resources. supported by in-band OAM MUST run on protection resources.
2.8.6. Topology-specific recovery mechanisms 2.5.6. Topology-specific recovery mechanisms
92 MPLS-TP MAY support recovery mechanisms that are optimized for 91 MPLS-TP MAY support recovery mechanisms that are optimized for
specific network topologies. These mechanisms MUST be specific network topologies. These mechanisms MUST be
interoperable with the mechanisms defined for arbitrary topology interoperable with the mechanisms defined for arbitrary topology
(mesh) networks to enable protection of end-to-end transport (mesh) networks to enable protection of end-to-end transport
paths. paths.
2.8.6.1. Ring protection 2.5.6.1. Ring protection
Several service providers have expressed a high level of interest in Several service providers have expressed a high level of interest in
operating MPLS-TP in ring topologies and require a high level of operating MPLS-TP in ring topologies and require a high level of
survivability function in these topologies. The requirements listed survivability function in these topologies. The requirements listed
below have been collected from these service providers and from the below have been collected from these service providers and from the
ITU-T. ITU-T.
The main objective in considering a specific topology (such as a The main objective in considering a specific topology (such as a
ring) is to determine whether it is possible to optimize any ring) is to determine whether it is possible to optimize any
mechanisms such that the performance of those mechanisms within the mechanisms such that the performance of those mechanisms within the
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mechanisms. mechanisms.
d. Minimize the amount of control and management plane transactions d. Minimize the amount of control and management plane transactions
during a maintenance operation (e.g., ring upgrade) - less than during a maintenance operation (e.g., ring upgrade) - less than
are required by other recovery mechanisms. are required by other recovery mechanisms.
e. When a control plane is supported, minimize the impact on e. When a control plane is supported, minimize the impact on
signaling and routing information exchange during protection - signaling and routing information exchange during protection -
less than are required by other recovery mechanisms. less than are required by other recovery mechanisms.
It may be observed that the requirements in Section 2.8.6.1 are fully It may be observed that the requirements in Section 2.5.6.1 are fully
compatible with the generic requirements expressed in Section 2.8 compatible with the generic requirements expressed in Section 2.5
through Section 2.8.6 inclusive, and that no requirements that are through Section 2.5.6 inclusive, and that no requirements that are
specific to ring topologies have been identified. specific to ring topologies have been identified.
93 MPLS-TP MUST include recovery mechanisms that operate in any 92 MPLS-TP MUST include recovery mechanisms that operate in any
single ring supported in MPLS-TP, and continue to operate within single ring supported in MPLS-TP, and continue to operate within
the single rings even when the rings are interconnected. the single rings even when the rings are interconnected.
94 When a network is constructed from interconnected rings, MPLS-TP 93 When a network is constructed from interconnected rings, MPLS-TP
MUST support recovery mechanisms that protect user data that MUST support recovery mechanisms that protect user data that
traverses more than one ring. This includes the possibility of traverses more than one ring. This includes the possibility of
failure of the ring-interconnect nodes and links. failure of the ring-interconnect nodes and links.
95 MPLS-TP recovery in a ring MUST protect unidirectional and 94 MPLS-TP recovery in a ring MUST protect unidirectional and
bidirectional P2P transport paths. bidirectional P2P transport paths.
96 MPLS-TP recovery in a ring MUST protect unidirectional P2MP 95 MPLS-TP recovery in a ring MUST protect unidirectional P2MP
transport paths. transport paths.
97 MPLS-TP 1+1 and 1:1 protection in a ring MUST support switching 96 MPLS-TP 1+1 and 1:1 protection in a ring MUST support switching
time within 50 ms from the moment of fault detection in a time within 50 ms from the moment of fault detection in a
network with a 16 nodes ring with less than 1200 km of fiber. network with a 16 nodes ring with less than 1200 km of fiber.
98 The protection switching time in a ring MUST be independent of 97 The protection switching time in a ring MUST be independent of
the number of LSPs crossing the ring. the number of LSPs crossing the ring.
99 The configuration and operation of recovery mechanisms in a ring 98 The configuration and operation of recovery mechanisms in a ring
MUST scale well with: MUST scale well with:
A. the number of transport paths (must be better than linear A. the number of transport paths (must be better than linear
scaling) scaling)
B. the number of nodes on the ring (must be at least as good as B. the number of nodes on the ring (must be at least as good as
linear scaling) linear scaling)
C. the number of ring interconnects (must be at least as good C. the number of ring interconnects (must be at least as good
as linear scaling) as linear scaling)
100 Recovery techniques used in a ring MUST NOT prevent the ring 99 Recovery techniques used in a ring MUST NOT prevent the ring
from being connected to a general MPLS-TP network in any from being connected to a general MPLS-TP network in any
arbitrary way, and MUST NOT prevent the operation of recovery arbitrary way, and MUST NOT prevent the operation of recovery
techniques in the rest of the network. techniques in the rest of the network.
101 Recovery techniques in a ring SHOULD be identical (or as similar 100 Recovery techniques in a ring SHOULD be identical (or as similar
as possible) to those in general transport networks to simplify as possible) to those in general transport networks to simplify
implementation and operations. However, this MUST NOT override implementation and operations. However, this MUST NOT override
any other requirement. any other requirement.
102 Recovery techniques in logical and physical rings SHOULD be 101 Recovery techniques in logical and physical rings SHOULD be
identical to simplify implementation and operation. However, identical to simplify implementation and operation. However,
this MUST NOT override any other requirement. this MUST NOT override any other requirement.
103 The default recovery scheme in a ring MUST be bidirectional 102 The default recovery scheme in a ring MUST be bidirectional
recovery in order to simplify the recovery operation. recovery in order to simplify the recovery operation.
104 The recovery mechanism in a ring MUST support revertive 103 The recovery mechanism in a ring MUST support revertive
switching, which MUST be the default behavior. This allows switching, which MUST be the default behavior. This allows
optimization of the use of the ring resources, and restores the optimization of the use of the ring resources, and restores the
preferred quality conditions for normal traffic (e.g., delay) preferred quality conditions for normal traffic (e.g., delay)
when the recovery mechanism is no longer needed. when the recovery mechanism is no longer needed.
105 The recovery mechanisms in a ring MUST support ways to allow 104 The recovery mechanisms in a ring MUST support ways to allow
administrative protection switching, to be distinguished from administrative protection switching, to be distinguished from
protection switching initiated by other triggers. protection switching initiated by other triggers.
106 It MUST be possible to lockout (disable) protection mechanisms 105 It MUST be possible to lockout (disable) protection mechanisms
on selected links (spans) in a ring (depending on operator's on selected links (spans) in a ring (depending on operator's
need). This may require lockout mechanisms to be applied to need). This may require lockout mechanisms to be applied to
intermediate nodes within a transport path. intermediate nodes within a transport path.
107 MPLS-TP recovery mechanisms in a ring: 106 MPLS-TP recovery mechanisms in a ring:
A. MUST include a mechanism to allow an implementation to A. MUST include a mechanism to allow an implementation to
handle (including the coordination of) coexisting requests handle (including the coordination of) coexisting requests
or triggers (i.e., multiple requests - not necessarily or triggers (i.e., multiple requests - not necessarily
arriving simultaneously and located anywhere in the ring) arriving simultaneously and located anywhere in the ring)
for protection switching based on priority. Note that such for protection switching based on priority. Note that such
coordination is the ring equivalent of the definition of coordination is the ring equivalent of the definition of
shared protection groups. shared protection groups.
B. SHOULD protect against multiple failures B. SHOULD protect against multiple failures
108 MPLS-TP recovery and reversion mechanisms in a ring MUST offer a 107 MPLS-TP recovery and reversion mechanisms in a ring MUST offer a
way to prevent frequent operation of recovery in the event of an way to prevent frequent operation of recovery in the event of an
intermittent defect. intermittent defect.
109 MPLS-TP MUST support the sharing of protection bandwidth in a 108 MPLS-TP MUST support the sharing of protection bandwidth in a
ring by allowing best effort traffic. ring by allowing best effort traffic.
110 MPLS-TP MUST support sharing of ring protection resources such 109 MPLS-TP MUST support sharing of ring protection resources such
that protection paths that are known not to be required that protection paths that are known not to be required
concurrently can share the same resources. concurrently can share the same resources.
2.9. QoS requirements 2.6. QoS requirements
Carriers require advanced traffic management capabilities to enforce Carriers require advanced traffic management capabilities to enforce
and guarantee the QoS parameters of customers' SLAs. and guarantee the QoS parameters of customers' SLAs.
Quality of service mechanisms are REQUIRED in an MPLS-TP network to Quality of service mechanisms are REQUIRED in an MPLS-TP network to
ensure: ensure:
111 Support for differentiated services and different traffic types 110 Support for differentiated services and different traffic types
with traffic class separation associated with different traffic. with traffic class separation associated with different traffic.
112 Enabling the provisioning and the guarantee of Service Level 111 Enabling the provisioning and the guarantee of Service Level
Specifications (SLS), with support for hard and relative end-to- Specifications (SLS), with support for hard and relative end-to-
end bandwidth guaranteed. end bandwidth guaranteed.
113 Support of services, which are sensitive to jitter and delay. 112 Support of services, which are sensitive to jitter and delay.
114 Guarantee of fair access, within a particular class, to shared 113 Guarantee of fair access, within a particular class, to shared
resources. resources.
115 Guaranteed resources for in-band control and management plane 114 Guaranteed resources for in-band control and management plane
traffic regardless of the amount of data plane traffic. traffic regardless of the amount of data plane traffic.
116 Carriers are provided with the capability to efficiently support 115 Carriers are provided with the capability to efficiently support
service demands over the MPLS-TP network. This MUST include service demands over the MPLS-TP network. This MUST include
support for a flexible bandwidth allocation scheme. support for a flexible bandwidth allocation scheme.
2.10. Security requirements 3. Requirements Discussed in Other Documents
3.1. Network Management requirements
For requirements related to network management functionality
(Management Plane in ITU-T terminology) for MPLS-TP, see the MPLS-TP
Network Management requirements document [I-D.ietf-mpls-tp-nm-req].
3.2. Operation, Administration and Maintenance (OAM) requirements
For requirements related to OAM functionality for MPLS-TP, see the
MPLS-TP OAM requirements document
[I-D.ietf-mpls-tp-oam-requirements].
3.3. Network performance monitoring requirements
For requirements related to performance monitoring functionality for
MPLS-TP, see the MPLS-TP OAM requirements document
[I-D.ietf-mpls-tp-oam-requirements].
3.4. Security requirements
For a description of the security threats relevant in the context of For a description of the security threats relevant in the context of
MPLS and GMPLS and the defensive techniques to combat those threats MPLS and GMPLS and the defensive techniques to combat those threats
see the Security Framework for MPLS & GMPLS Networks see the Security Framework for MPLS & GMPLS Networks
[I-D.ietf-mpls-mpls-and-gmpls-security-framework]. [I-D.ietf-mpls-mpls-and-gmpls-security-framework].
3. IANA Considerations For a description of additional security threats relevant in the
context of MPLS-TP and the defensive techniques to combat those
threats see the Security Framework for MPLS-TP
[I-D.ietf-fang-mpls-tp-security-framework].
4. IANA Considerations
This document makes no request of IANA. This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an Note to RFC Editor: this section may be removed on publication as an
RFC. RFC.
4. Security Considerations 5. Security Considerations
See Section 2.10. See Section 3.4.
5. Acknowledgements 6. Acknowledgements
The authors would like to thank all members of the teams (the Joint The authors would like to thank all members of the teams (the Joint
Working Team, the MPLS Interoperability Design Team in the IETF, and Working Team, the MPLS Interoperability Design Team in the IETF, and
the T-MPLS Ad Hoc Group in the ITU-T) involved in the definition and the T-MPLS Ad Hoc Group in the ITU-T) involved in the definition and
specification of MPLS Transport Profile. specification of MPLS Transport Profile.
The authors would also like to thank Loa Andersson, Dieter Beller, The authors would also like to thank Loa Andersson, Dieter Beller,
Lou Berger, Italo Busi, John Drake, Adrian Farrel, Annamaria Lou Berger, Italo Busi, John Drake, Adrian Farrel, Annamaria
Fulignoli, Pietro Grandi, Eric Gray, Neil Harrison, Jia He, Huub van Fulignoli, Pietro Grandi, Eric Gray, Neil Harrison, Jia He, Huub van
Helvoort, Enrique Hernandez-Valencia, Wataru Imajuku, Kam Lam, Andy Helvoort, Enrique Hernandez-Valencia, Wataru Imajuku, Kam Lam, Andy
skipping to change at page 29, line 28 skipping to change at page 29, line 39
Tancevski, Tomonori Takeda, Yuji Tochio, Alexander Vainshtein, Eve Tancevski, Tomonori Takeda, Yuji Tochio, Alexander Vainshtein, Eve
Varma and Maarten Vissers for their comments and enhancements to the Varma and Maarten Vissers for their comments and enhancements to the
text. text.
An ad hoc discussion group consisting of Stewart Bryant, Italo Busi, An ad hoc discussion group consisting of Stewart Bryant, Italo Busi,
Andrea Digiglio, Li Fang, Adrian Farrel, Jia He, Huub van Helvoort, Andrea Digiglio, Li Fang, Adrian Farrel, Jia He, Huub van Helvoort,
Feng Huang, Harald Kullman, Han Li, Hao Long and Nurit Sprecher Feng Huang, Harald Kullman, Han Li, Hao Long and Nurit Sprecher
provided valuable input to the requirements for deployment and provided valuable input to the requirements for deployment and
survivability in ring topologies. survivability in ring topologies.
6. References 7. References
6.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001. Label Switching Architecture", RFC 3031, January 2001.
[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to- [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
Edge (PWE3) Architecture", RFC 3985, March 2005. Edge (PWE3) Architecture", RFC 3985, March 2005.
skipping to change at page 30, line 14 skipping to change at page 30, line 27
International Telecommunications Union, "Architecture for International Telecommunications Union, "Architecture for
the automatically switched optical network (ASON)", ITU- the automatically switched optical network (ASON)", ITU-
T Recommendation G.8080, June 2006. T Recommendation G.8080, June 2006.
[ITU.G8080.2008] [ITU.G8080.2008]
International Telecommunications Union, "Architecture for International Telecommunications Union, "Architecture for
the automatically switched optical network (ASON) the automatically switched optical network (ASON)
Amendment 1", ITU-T Recommendation G.8080 Amendment 1, Amendment 1", ITU-T Recommendation G.8080 Amendment 1,
March 2008. March 2008.
6.2. Informative References 7.2. Informative References
[RFC4139] Papadimitriou, D., Drake, J., Ash, J., Farrel, A., and L. [RFC4139] Papadimitriou, D., Drake, J., Ash, J., Farrel, A., and L.
Ong, "Requirements for Generalized MPLS (GMPLS) Signaling Ong, "Requirements for Generalized MPLS (GMPLS) Signaling
Usage and Extensions for Automatically Switched Optical Usage and Extensions for Automatically Switched Optical
Network (ASON)", RFC 4139, July 2005. Network (ASON)", RFC 4139, July 2005.
[RFC4258] Brungard, D., "Requirements for Generalized Multi-Protocol [RFC4258] Brungard, D., "Requirements for Generalized Multi-Protocol
Label Switching (GMPLS) Routing for the Automatically Label Switching (GMPLS) Routing for the Automatically
Switched Optical Network (ASON)", RFC 4258, November 2005. Switched Optical Network (ASON)", RFC 4258, November 2005.
[RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the [RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the
Interpretation of Generalized Multiprotocol Label Interpretation of Generalized Multiprotocol Label
Switching (GMPLS) Terminology within the Context of the Switching (GMPLS) Terminology within the Context of the
ITU-T's Automatically Switched Optical Network (ASON) ITU-T's Automatically Switched Optical Network (ASON)
Architecture", RFC 4397, February 2006. Architecture", RFC 4397, February 2006.
[RFC4427] Mannie, E. and D. Papadimitriou, "Recovery (Protection and [RFC4427] Mannie, E. and D. Papadimitriou, "Recovery (Protection and
Restoration) Terminology for Generalized Multi-Protocol Restoration) Terminology for Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 4427, March 2006. Label Switching (GMPLS)", RFC 4427, March 2006.
[I-D.ietf-fang-mpls-tp-security-framework]
Fang, L. and B. Niven-Jenkins, "Security Framework for
MPLS-TP", draft-fang-mpls-tp-security-framework-00 (work
in progress), July 2008.
[I-D.ietf-mpls-mpls-and-gmpls-security-framework] [I-D.ietf-mpls-mpls-and-gmpls-security-framework]
Fang, L. and M. Behringer, "Security Framework for MPLS Fang, L. and M. Behringer, "Security Framework for MPLS
and GMPLS Networks", and GMPLS Networks",
draft-ietf-mpls-mpls-and-gmpls-security-framework-05 (work draft-ietf-mpls-mpls-and-gmpls-security-framework-05 (work
in progress), November 2008. in progress), November 2008.
[I-D.ietf-mpls-tp-nm-req] [I-D.ietf-mpls-tp-nm-req]
Lam, H., Mansfield, S., and E. Gray, "MPLS TP Network Lam, H., Mansfield, S., and E. Gray, "MPLS TP Network
Management Requirements", draft-ietf-mpls-tp-nm-req-01 Management Requirements", draft-ietf-mpls-tp-nm-req-01
(work in progress), April 2009. (work in progress), April 2009.
skipping to change at page 32, line 4 skipping to change at page 32, line 22
Email: benjamin.niven-jenkins@bt.com Email: benjamin.niven-jenkins@bt.com
Deborah Brungard (editor) Deborah Brungard (editor)
AT&T AT&T
Rm. D1-3C22 - 200 S. Laurel Ave. Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748 Middletown, NJ 07748
USA USA
Email: dbrungard@att.com Email: dbrungard@att.com
Malcolm Betts (editor) Malcolm Betts (editor)
Nortel Networks Huawei Technologies
3500 Carling Avenue
Ottawa, Ontario K2H 8E9
Canada
Email: betts01@nortel.com Email: malcolm.betts@huawei.com
Nurit Sprecher Nurit Sprecher
Nokia Siemens Networks Nokia Siemens Networks
3 Hanagar St. Neve Ne'eman B 3 Hanagar St. Neve Ne'eman B
Hod Hasharon, 45241 Hod Hasharon, 45241
Israel Israel
Email: nurit.sprecher@nsn.com Email: nurit.sprecher@nsn.com
Satoshi Ueno Satoshi Ueno
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