draft-ietf-ccamp-gmpls-ason-routing-reqts-01.txt   draft-ietf-ccamp-gmpls-ason-routing-reqts-02.txt 
CCAMP Working Group Wesam Alanqar (Sprint) CCAMP Working Group Wesam Alanqar (Sprint)
Internet Draft Deborah Brungard (ATT) Internet Draft Deborah Brungard (ATT)
Category: Informational Dave Meyer (Cisco Systems) Category: Informational Dave Meyer (Cisco Systems)
Lyndon Ong (Ciena) Lyndon Ong (Ciena)
Expiration Date: May 2004 Dimitri Papadimitriou (Alcatel) Expiration Date: July 2004 Dimitri Papadimitriou (Alcatel)
Jonathan Sadler (Tellabs) Jonathan Sadler (Tellabs)
Stephen Shew (Nortel) Stephen Shew (Nortel)
December 2003 February 2004
Requirements for Generalized MPLS (GMPLS) Routing Requirements for Generalized MPLS (GMPLS) Routing
for Automatically Switched Optical Network (ASON) for Automatically Switched Optical Network (ASON)
draft-ietf-ccamp-gmpls-ason-routing-reqts-01.txt draft-ietf-ccamp-gmpls-ason-routing-reqts-02.txt
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 RFC-2026. all provisions of Section 10 of RFC-2026.
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. Internet-Drafts are draft documents valid for a maximum of Drafts. Internet-Drafts are draft documents valid for a maximum of
skipping to change at line 46 skipping to change at line 46
Abstract Abstract
The Generalized MPLS (GMPLS) suite of protocols has been defined to The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different control different switching technologies as well as different
applications. These include support for requesting TDM connections applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs). including SONET/SDH and Optical Transport Networks (OTNs).
This document concentrates on the routing requirements on the GMPLS This document concentrates on the routing requirements on the GMPLS
suite of protocols to support the capabilities and functionalities suite of protocols to support the capabilities and functionalities
of an Automatically Switched Optical Network (ASON). for an Automatically Switched Optical Network (ASON) as defined by
ITU-T.
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1. Contributors 1. Contributors
This document is the result of the CCAMP Working Group ASON Routing This document is the result of the CCAMP Working Group ASON Routing
Requirements design team joint effort. Requirements design team joint effort.
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119. this document are to be interpreted as described in RFC-2119.
3. Introduction 3. Introduction
The GMPLS suite of protocol provides support for controlling The GMPLS suite of protocols provides among other capability support
different switching technologies as well as different applications. for controlling different switching technologies. These include
These include support for requesting TDM connections including support for requesting TDM connections utilizing SONET/SDH (see ANSI
SONET/SDH (see ANSI T1.105/ITU-T G.707) as well as Optical Transport T1.105/ITU-T G.707) as well as Optical Transport Networks (see ITU-T
Networks (see ITU-T G.709). However, there are certain capabilities G.709). However, there are certain capabilities that are needed to
that are needed to support the ITU-T G.8080 control plane support the ITU-T G.8080 control plane architecture for the
architecture for the Automatically Switched Optical Network (ASON). Automatically Switched Optical Network (ASON). Therefore, it is
Therefore, it is desirable to understand the corresponding desirable to understand the corresponding requirements for the GMPLS
requirements for the GMPLS protocol suite. The ASON control plane protocol suite. The ASON control plane architecture is defined in
architecture is defined in [G.8080] and ASON routing requirements [G.8080] and ASON routing requirements are identified in [G.7715]
are identified in [G.7715] and refined in [G.7715.1] for link state and refined in [G.7715.1] for link state architectures. These
architectures. These recommendations provide functional requirements recommendations provide functional requirements and architecture,
and architecture, they provide a protocol neutral approach. they provide a protocol neutral approach.
This document focuses on the routing requirements for the GMPLS This document focuses on the routing requirements for the GMPLS
suite of protocols to support the capabilities and functionalities suite of protocols to support the capabilities and functionality of
of ASON control planes. It discusses the requirements for GMPLS ASON control planes. It discusses the requirements for GMPLS routing
routing that MAY subsequently lead to additional backward compatible that MAY subsequently lead to additional backward compatible
extensions to support the capabilities specified in the above extensions to support the capabilities specified in the above
referenced document. A description of backward compatibility referenced documents. A description of backward compatibility
considerations is provided in Section 5. Nonetheless, any protocol considerations is provided in Section 5. Nonetheless, any protocol
(in particular, routing) design or suggested protocol extensions is (in particular, routing) design or suggested protocol extensions is
strictly outside the scope of this document. An ASON (Routing) strictly outside the scope of this document. An ASON (Routing)
terminology section is provided in Appendix 1 and Appendix 2. terminology section is provided in Appendix 1 and Appendix 2.
The ASON model distinguishes reference points (representing points The ASON model distinguishes reference points (representing points
of protocol information exchange) defined (1) between an of information exchange) defined (1) between an administrative
administrative domain and a user (user-network interface or UNI), domain and a user (user-network interface or UNI), (2) between
(2) between administrative domains or within an administrative administrative domains or within an administrative domain between
domain between different control domains (external network-network different control domains (external network-network interface or E-
interface or E-NNI) and, (3) within the same administrative domain NNI) and, (3) within the same administrative domain between control
between control components (or simply controllers) of the same components (or simply controllers) of the same control domain
control domain (internal network-network interface or I-NNI). The (internal network-network interface or I-NNI). The ASON model allows
ASON model allows for the protocols used within different control for the protocols used within different control domains to be
domains to be different; and for the protocol used between control different; and for the protocol used between control domains to be
domains to be different than the protocols used within control different than the protocols used within control domains. I-NNI
domains. I-NNI interfaces are located between protocol controllers control interfaces are located between protocol controllers within a
within a control domain. E-NNI interfaces are located on protocol control domain. E-NNI control interfaces are located on protocol
controllers between control domains. controllers between control domains.
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The term routing information refers to the abstract representation The term routing information refers to the abstract representation
of network routing related information such as node and link of network routing related information such as node and link
attributes (see Section 4.5). No routing information is passed over attributes (see Section 4.5). No routing information is passed over
the UNI. Routing information exchanged over the NNI is subject to the UNI. Routing information exchanged over the NNI is subject to
the policy constraints at individual NNIs. The routing information the policy constraints at individual NNIs. The routing information
exchanged over the E-NNI encapsulates the common semantics of the exchanged over the E-NNI encapsulates the common semantics of the
individual domain information while allowing different individual domain information while allowing different
representation within each domain. representation within each domain.
The ASON routing architecture is based on the following assumptions: The ASON routing architecture is based on the following assumptions:
- A carrier's network is subdivided as Routing Areas (RAs). Each RA - A carrier's network is subdivided as Routing Areas (RAs). Each RA
shall be uniquely identifiable within a carrier's network (i.e. shall be uniquely identifiable within a carrier's network (i.e.
administrative domain). Partitioning into RAs provides for routing administrative domain). RAs partitioning provide for routing
information abstraction, thereby enabling scalable routing. information abstraction, thereby enabling scalable routing.
- Routing Controllers (RC) provide for the exchange of routing - Routing Controllers (RC) provide for the exchange of routing
information between and within a RA. The routing information information between and within a RA. The routing information
exchanged between RCs is subject to policy constraints imposed at exchanged between RCs is subject to policy constraints imposed at
reference points (E-NNI and I-NNI). reference points (E-NNI and I-NNI).
- A RA MAY support different routing protocols. There SHOULD NOT be - For a RA, the set of RCs is referred to as a routing (control)
any dependencies on the different routing protocols used. domain. The RC MAY support more than one routing protocol (i.e. an
- For a RA, the cluster of RCs is referred to as a routing domain. RC MAY support multiple Protocol Controller (PCs)). There SHOULD
The routing information exchanged between routing domains (i.e. NOT be any dependencies on the different routing protocols used.
- The routing information exchanged between routing domains (i.e.
inter-domain) is independent of both the intra-domain routing inter-domain) is independent of both the intra-domain routing
protocol and the intra-domain control distribution choice(s), e.g. protocol and the intra-domain control distribution choice(s), e.g.
centralized, fully distributed. centralized, fully distributed.
- The routing adjacency topology and transport network topology - The routing adjacency topology (i.e. the associated PC
SHALL NOT be assumed to be congruent. connectivity topology) and the transport network topology SHALL
NOT be assumed to be congruent.
The following functionality is expected from GMPLS routing to The following functionality is expected from GMPLS routing to
instantiate ASON routing realization (see [G.7715]): instantiate ASON routing realization (see [G.7715] and [G.7715.1]):
- support multiple hierarchical levels of RAs - support multiple hierarchical levels of RAs; the number of
hierarchical levels to be supported is routing protocol
implementation specific.
- support hierarchical routing information dissemination including - support hierarchical routing information dissemination including
summarized routing information summarized routing information
- support for multiple links between nodes and RAs (allowing for - support for multiple links between nodes (and between RAs) and for
link and node diversity) link and node diversity
- support architectural evolution in terms of the number of levels - support architectural evolution in terms of the number of levels
of hierarchies, aggregation and segmentation of RAs of hierarchies, aggregation and segmentation of RAs
- support routing information based on a common set of information - support routing information based on a common set of information
elements as defined in [G.7715] and [G.7715.1], divided between elements as defined in [G.7715] and [G.7715.1], divided between
attributes pertaining to links and abstract nodes (each attributes pertaining to links and abstract nodes (each
representing either a sub-network or simply a node). [G.7715] representing either a sub-network or simply a node). [G.7715]
recognizes that the manner in which the routing information is recognizes that the manner in which the routing information is
represented and exchanged will vary with the routing protocol represented and exchanged will vary with the routing protocol
used. used.
Also, the behaviour of GMPLS routing is expected to be such that: Also, the behaviour of GMPLS routing is expected to be such that:
- it is scalable with respect to the number of links, nodes and RAs - it is scalable with respect to the number of links, nodes and RAs
- in response to a routing event (e.g. topology update, reachability - in response to a routing event (e.g. topology update, reachability
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update), it delivers convergence and damping against flapping update), it delivers convergence and damping against flapping
- it fulfils the operational security objectives where required - it fulfils the operational security objectives where required
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4. ASON Requirements for GMPLS Routing 4. ASON Requirements for GMPLS Routing
The description of the ASON routing components (see Appendix 2) is The description of the ASON routing components (see Appendix 2) is
provided in terms of routing functionality. This description is only provided in terms of routing functionality. This description is only
conceptual: no physical partitioning of these functions is implied. conceptual: no physical partitioning of these functions is implied.
The Routing Controller (RC) component receive routing information The Routing Controller (RC) components receive routing information
from their associated Link Resource Manager(s) (LRMs) regarding TE from their associated Link Resource Manager(s) (LRMs) regarding TE
links and store this information in the Routing Information Database links and store this information in the Routing Information Database
(RDB). The RDB is replicated at each RC within the same Routing Area (RDB). The RDB is replicated at each RC within the same Routing Area
(RA), and MAY contain information about multiple transport plane (RA), and MAY contain information about multiple transport plane
network layers. Whenever the state of a TE link (or component link) network layers. Whenever the state of a TE link (or component link)
changes, the LRM informs the corresponding RC, which in turn updates changes, the LRM informs the corresponding RC, which in turn updates
its associated RDB. In order to assure RDB synchronization, the RCs its associated RDB. In order to assure RDB synchronization, the RCs
co-operate and exchange routing information. In this context, co-operate and exchange routing information. In this context,
communication between RCs is realized using a particular routing communication between RCs is realized using a particular routing
protocol represented by the protocol controller (PC) component and protocol represented by the protocol controller (PC) component and
the protocol messages are conveyed over the Signaling Control the protocol messages are conveyed over the Signaling Control
Network (SCN). The PC MAY convey information for one or more Network (SCN). The PC MAY convey information for one or more
transport network layers. transport network layers. Moreover, as [G7715.1] states and
illustrates in its Figure 1, ASON routing protocol requirements
deals exclusively with the PC to PC communication of the (RC)
routing information; therefore any other communication between any
other functional component(s) (e.g. SC, LRM) is also outside the
scope of this document.
Note: the RC can be thought as the function processing the TE Note: the RC can be thought of as the function processing the TE
database populated by the link local/remote component and TE links database populated by the link local/remote component and TE links
(LRM) and by the network wide TE links through the PC which (LRM) and by the network wide TE links through the PC which
processes the protocol specific routing exchanges. The SCN processes the protocol specific routing exchanges. The SCN
corresponds to the IP control plane topology enabling routing corresponds to the IP control plane topology enabling routing
exchanges between GMPLS controllers (i.e. the routing adjacencies). exchanges between GMPLS controllers (i.e. the routing adjacencies).
The next sections detail the requirements for GMPLS routing to
support the following ASON routing functions.
4.1 Multiple Hierarchical Levels 4.1 Multiple Hierarchical Levels
Routing Areas (RAs) provide for routing information abstraction, [G.8080] introduces the concept of Routing Area (RA). RAs provide
thereby enabling scalable routing information representation. for routing information abstraction, thereby enabling scalable
[G.7715] describes the use of hierarchy as one possible choice for routing information representation. Except for the single RA case,
routing area organization. RAs MAY be hierarchically contained: a RAs are hierarchically contained: a higher level (parent) RA
higher level (parent) RA contains lower level (child) RAs that in contains lower level (child) RAs that in turn MAY also contain RAs,
turn MAY also contain RAs, etc. Thus, RAs contain RAs that etc. Thus, RAs contain RAs that recursively define successive
recursively define successive hierarchical routing levels. The hierarchical routing levels.
realization of the routing paradigm to support hierarchical routing
levels and the number of hierarchical levels to be supported is
protocol specific and outside the scope of this document.
Note: an RA can be considered as representing either an Autonomous However, the RA containment relationship describes only an
System (AS) or a canonical IGP routing area, both are sometimes architectural hierarchical organization of RAs. It does not restrict
referred to as routing regions (or simply regions). the routing protocol realization (e.g. OSPF multi-areas, path
computation, etc.). Moreover, the realization of the routing
paradigm to support hierarchical routing and the number of
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hierarchical levels to be supported is routing protocol specific and
outside the scope of this document.
ASON routing components are identified by values that MAY be drawn ASON routing components are identified by values that MAY be drawn
from several identifier spaces. The use of identifiers in a routing from several identifier spaces (see [G.7715.1]). The use of
protocol realization is implementation specific and outside the identifiers in a routing protocol realization is implementation
scope of this document. specific and outside the scope of this document.
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In a multi-level routing hierarchy, it is necessary to distinguish In a multi-level routing hierarchy, it is necessary to distinguish
among RCs within a level and RCs at different levels of the routing among RCs within a level and RCs at different levels of the routing
hierarchy. Before any pair of RCs establishes communication, they hierarchy. Before any pair of RCs establishes communication, they
must verify they belong to the same RA. An RA identifier (RA ID) is MUST verify they belong to the same RA (see Section 4.2). A RA
required to provide the scope within which the RCs can communicate. identifier (RA ID) is required to provide the scope within which the
To distinguish between RCs within the same RA, an RC identifier (RC RCs can communicate. To distinguish between RCs within the same RA,
ID) is required; the RC ID must be unique within its containing RA. an RC identifier (RC ID) is required; the RC ID must be unique
within its containing RA.
Note: RA IDs MAY be associated with a transport plane name space A RA represents a partition of the data plane and its identifier
whereas RC IDs are associated with a control plane name space. (i.e. RA ID) is used within the control plane as a reference to the
data plane partition. RA IDs MAY be associated with a transport
plane name space whereas RC IDs are associated with a control plane
name space.
4.2 Hierarchical Routing Information Dissemination 4.2 Hierarchical Routing Information Dissemination
Routing information MAY be exchanged between adjacent levels of the Routing information can be exchanged between adjacent levels of the
routing hierarchy i.e. Level N+1 and N, where Level N represents the routing hierarchy i.e. Level N+1 and N, where Level N represents the
RAs contained by Level N+1. The links connecting RAs MAY be viewed RAs contained by Level N+1. The links connecting RAs MAY be viewed
as external links, and the links representing connectivity within an as external links, and the links representing connectivity within an
RA MAY be viewed as internal links. RA MAY be viewed as internal links.
The physical location of RCs at adjacent levels, their relationship The physical location of RCs at adjacent levels, their relationship
and their communication protocol are outside the scope of this and their communication protocol are outside the scope of this
document. No assumption is made regarding how RCs communicate document. No assumption is made regarding how RCs communicate
between levels. Information exchange between an RC, its parent, and between levels. If routing information is exchanged between a RC,
its child RCs, SHOULD include reachability and MAY include (upon its parent, and its child RCs, it SHOULD include reachability and
policy decision) node and link topology. MAY include (upon policy decision) node and link topology.
Multiple RCs within a RA MAY transform (filter, summarize, etc.) and Multiple RCs within a RA MAY transform (filter, summarize, etc.) and
then forward information to RCs at different levels. However in this then forward information to RCs at different levels. However in this
case the resulting information at the receiving level must be self- case the resulting information at the receiving level must be self-
consistent; this MAY be achieved using a number of mechanisms. consistent; this MAY be achieved using a number of mechanisms.
Note: there is no relationship between multi-layer and multi-level
routing. The former implies a single routing protocol instance for
multiple transport switching layers whereas the latter implies a
hierarchical routing topology for one transport switching layer.
4.2.1 Communication between Adjacent Routing Levels 4.2.1 Communication between Adjacent Routing Levels
1. Type of Information Exchanged 1. Type of Information Exchanged
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The type of information flowing upward (i.e. Level N to Level The type of information flowing upward (i.e. Level N to Level
N+1) and the information flowing downward (i.e. Level N+1 to N+1) and the information flowing downward (i.e. Level N+1 to
Level N) are used for similar purposes, namely, the exchange of Level N) are used for similar purposes, namely, the exchange of
reachability information and summarized topology information to reachability information and summarized topology information to
allow routing across multiple RAs. The summarization of topology allow routing across multiple RAs. The summarization of topology
information may impact the accuracy of routing and MAY require information may impact the accuracy of routing and MAY require
additional path calculation. additional path calculation.
The following information exchange are expected: The following information exchange are expected:
- Level N+1 visibility to Level N reachability and topology (or - Level N+1 visibility to Level N reachability and topology (or
upward information communication) allowing RC(s) at level N+1 upward information communication) allowing RC(s) at level N+1
to determine the reachable endpoints from Level N. to determine the reachable endpoints from Level N.
- Level N visibility to Level N+1 reachability and topology (or - Level N visibility to Level N+1 reachability and topology (or
downward information communication) allowing RC(s) in an RA at downward information communication) allowing RC(s) in an RA at
Level N to develop paths to reachable endpoints outside of the Level N to develop paths to reachable endpoints outside of the
RA. RA.
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2. Interactions between Upward and Downward Communication 2. Interactions between Upward and Downward Communication
When both upward and downward information exchanges contain When both upward and downward information exchanges contain
endpoint reachability information, a feedback loop could endpoint reachability information, a feedback loop could
potentially be created. Consequently, the routing protocol MUST potentially be created. Consequently, the routing protocol MUST
include a mechanism to prevent re-introduction of information include a method to:
propagated into the Level N RA back to the external level RA from - prevent information propagated from a Level N+1 RA into the
which this information has been initially received. Level N RA to be re-introduced into the Level N+1 RA, and
- prevent information propagated from a Level N-1 RA into the
Level N RA to be re-introduced into the Level N-1 RA.
The routing protocol is required to differentiate the routing The routing protocol is required to differentiate the routing
information originated at a given level RA from the one derived information originated at a given level RA from the one derived
using the routing information received from its external RAs using the routing information received from its external RAs
(regardless of the level of the corresponding RCs). This is a (regardless of the level of the corresponding RCs). This is a
necessary condition to be fulfilled by routing protocols to be necessary condition to be fulfilled by routing protocols to be
loop free. loop free.
Also, for ASON, the routing information exchange may generate Also, for ASON, the routing information exchange may generate
transient loops at the data plane if no route recording is used transient loops at the data plane if no route recording is used
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3. Method of Communication 3. Method of Communication
Two approaches exist for communication between Level N and N+1. Two approaches exist for communication between Level N and N+1.
- The first approach places an instance of a Level N routing - The first approach places an instance of a Level N routing
function and an instance of a Level N+1 routing function in the function and an instance of a Level N+1 routing function in the
same system. The communications interface is within a single same system. The communications interface is within a single
system and is thus not an open interface subject to system and is thus not an open interface subject to
standardization. standardization.
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- The second approach places the Level N routing function on a - The second approach places the Level N routing function on a
separate system from the Level N+1 routing function. In this separate system from the Level N+1 routing function. In this
case, a communication interface must be used between the case, a communication interface must be used between the
systems containing the routing functions for different levels. systems containing the routing functions for different levels.
This communication interface and mechanisms are outside the This communication interface and mechanisms are outside the
scope of this document. scope of this document.
4.2.2 Configuring the Routing Hierarchy 4.2.2 Configuring the Routing Hierarchy
The RC MUST support static (i.e. operator assisted) and MAY support The RC MUST support static (i.e. operator assisted) and MAY support
automated configuration of the information describing its automated configuration of the information describing its
relationship to parent and its child within the hierarchical routing relationship to parent and its child within the hierarchical routing
structure (including RA ID and RC ID). When applied recursively, the structure (including RA ID and RC ID). When applied recursively, the
whole hierarchy is thus configured. whole hierarchy is thus configured.
4.2.3 Configuring RC Adjacencies 4.2.3 Configuring RC Adjacencies
The RC MUST support static (i.e. operator assisted) and MAY support The RC MUST support static (i.e. operator assisted) and MAY support
automated configuration of the information describing its control automated configuration of the information describing its control
adjacencies to other RCs within a RA. The routing protocol SHOULD
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adjacencies to other RCs within an RA. The protocol SHOULD support [G.7715]. The latter includes congruent topology (with distributed
all the types of adjacencies described in Section 9 of [G.7715]. RC) and hubbed topology (with designated RC).
4.3 Evolution 4.3 Evolution
The containment relationships of RAs MAY change, motivated by events The containment relationships of RAs MAY change, motivated by events
such as mergers, acquisitions, and divestitures. such as mergers, acquisitions, and divestitures.
The routing protocol SHOULD be capable of supporting architectural The routing protocol SHOULD be capable of supporting architectural
evolution in terms of number of hierarchical levels, as well as evolution in terms of number of hierarchical levels, as well as
aggregation and segmentation of RAs. RA IDs uniqueness within an aggregation and segmentation of RAs. RA IDs uniqueness within an
administrative domain MAY facilitate these operations. The routing administrative domain MAY facilitate these operations. The routing
protocol is not expected to automatically initiate and/or execute protocol is not expected to automatically initiate and/or execute
these operations. these operations.
4.4 Multiple Links between Nodes and RAs 4.4 Multiple Links between Nodes and RAs
See Section 4.5.3 See Section 4.5.1
4.5 Routing Attributes 4.5 Routing Attributes
Routing for transport networks is performed on a per layer basis, Routing for transport networks is performed on a per layer basis,
where the routing paradigms MAY differ among layers and within a where the routing paradigms MAY differ among layers and within a
layer. Not all equipments support the same set of transport layers layer. Not all equipment support the same set of transport layers or
nor the same degree of connection flexibility at any given layer. A the same degree of connection flexibility at any given layer. A
server layer trail may support various clients, involving different server layer trail may support various clients, involving different
adaptation functions. Additionally, equipment may support variable adaptation functions. Additionally, equipment may support variable
adaptation functionality, whereby a single server layer trail adaptation functionality, whereby a single server layer trail
dynamically supports different multiplexing structures. As a result, dynamically supports different multiplexing structures. As a result,
routing information MAY include layer specific, layer independent, routing information MAY include layer specific, layer independent,
and client/server adaptation information. and client/server adaptation information.
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4.5.1 Taxonomy of Attributes 4.5.1 Taxonomy of Attributes
Attributes can be organized according to the following categories: Attributes can be organized according to the following categories:
- Node related or link related - Node related or link related
- Provisioned, negotiated or automatically configured - Provisioned, negotiated or automatically configured
- Inherited or layer specific (client layers can inherit some - Inherited or layer specific (client layers can inherit some
attributes from the server layer while other attributes like attributes from the server layer while other attributes like
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(Component) link attributes can be statically or automatically (Component) link attributes can be statically or automatically
configured for each transport network layer. This may lead to configured for each transport network layer. This may lead to
unnecessary repetition. Hence, the inheritance property of unnecessary repetition. Hence, the inheritance property of
attributes can also be used to optimize the configuration process. attributes can also be used to optimize the configuration process.
TE links are configured through grouping of component links. TE links are configured through grouping of component links.
Grouping MAY be based on different link attributes (e.g., SRLG Grouping MAY be based on different link attributes (e.g., SRLG
information, link weight, etc). information, link weight, etc).
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Two RAs may be linked by one or more TE links. Multiple TE links may Two RAs may be linked by one or more TE links. Multiple TE links may
be required when component links are not equivalent for routing be required when component links are not equivalent for routing
purposes with respect to the RAs they are attached to, or to the purposes with respect to the RAs they are attached to, or to the
containing RA, or when smaller groupings are required. containing RA, or when smaller groupings are required.
4.5.2 Commonly Advertised Information 4.5.2 Commonly Advertised Information
Advertisements MAY contain the following common set of information Advertisements MAY contain the following common set of information
regardless of whether they are link or node related: regardless of whether they are link or node related:
- RA ID of which the advertisement is bounded - RA ID of which the advertisement is bounded
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The following Node Attributes are defined: The following Node Attributes are defined:
Attribute Capability Usage Attribute Capability Usage
----------- ----------- --------- ----------- ----------- ---------
Node ID REQUIRED REQUIRED Node ID REQUIRED REQUIRED
Reachability REQUIRED OPTIONAL Reachability REQUIRED OPTIONAL
Table 1. Node Attributes Table 1. Node Attributes
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Reachability information describes the set of endpoints that are Reachability information describes the set of endpoints that are
reachable by the associated node. It MAY be advertised as a set of reachable by the associated node. It MAY be advertised as a set of
associated address prefixes or a set of associated TE link IDs, associated address prefixes or a set of associated TE link IDs,
consistently assigned within an administrative domain. consistently assigned within an administrative domain.
Note: no distinction is made between nodes that may have further Note: no distinction is made between nodes that may have further
internal details (i.e., abstract nodes) and those that cannot be internal details (i.e., abstract nodes) and those that cannot be
decomposed any further. decomposed any further.
4.5.4 Link Attributes 4.5.4 Link Attributes
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The following Link Attributes are defined: The following Link Attributes are defined:
Link Attribute Capability Usage Link Attribute Capability Usage
--------------- ----------- --------- --------------- ----------- ---------
Local TE link ID REQUIRED REQUIRED Local TE link ID REQUIRED REQUIRED
Remote TE link ID REQUIRED REQUIRED Remote TE link ID REQUIRED REQUIRED
TE Link Characteristics Table 3 TE Link Characteristics Table 3
Table 2. Link Attributes Table 2. Link Attributes
W.Alanqar et al. - Expires May 2004 8
The TE link ID must be sufficient to uniquely identify the The TE link ID must be sufficient to uniquely identify the
corresponding transport plane resource taking into account corresponding transport plane resource taking into account
separation of data and control planes. The TE link ID format is separation of data and control planes. The TE link ID format is
routing protocol specific. routing protocol specific.
Note: when the remote end of a TE link is located outside of the RA, Note: when the remote end of a TE link is located outside of the RA,
the remote TE link ID is OPTIONAL. the remote TE link ID is OPTIONAL.
The following TE link characteristic attributes are defined: The following TE link characteristic attributes are defined:
skipping to change at line 457 skipping to change at line 479
component link is at a border or within an LSP region (see [HIER]) component link is at a border or within an LSP region (see [HIER])
- Link Capacity: This provides the sum of the available and - Link Capacity: This provides the sum of the available and
potential bandwidth capacity for a particular network transport potential bandwidth capacity for a particular network transport
layer. Other capacity measures MAY be further considered. layer. Other capacity measures MAY be further considered.
- Link Availability: This represents the survivability capability - Link Availability: This represents the survivability capability
such as the protection type associated with the link. such as the protection type associated with the link.
- Diversity Support: This represents diversity information such as - Diversity Support: This represents diversity information such as
W.Alanqar et al. - Expires July 2004 9
the SRLG information associated with the link. the SRLG information associated with the link.
- Local Adaptation Support: This indicates the set of client layer - Local Adaptation Support: This indicates the set of client layer
adaptations supported by the local component link associated to adaptations supported by the local component link associated to
the local TE link. This can only exist when the "Local Connection the local TE link. This can only exist when the "Local Connection
Type" indicates crossing of an LSP Region or can be flexibly Type" indicates crossing of an LSP Region or can be flexibly
assigned to be at a border or within an LSP region (see [HIER]). assigned to be at a border or within an LSP region (see [HIER]).
TE link Characteristics Capability Usage TE link Characteristics Capability Usage
----------------------- ---------- --------- ----------------------- ---------- ---------
skipping to change at line 478 skipping to change at line 502
Link Weight REQUIRED OPTIONAL Link Weight REQUIRED OPTIONAL
Resource Class REQUIRED OPTIONAL Resource Class REQUIRED OPTIONAL
Local Connection Types REQUIRED OPTIONAL Local Connection Types REQUIRED OPTIONAL
Link Capacity REQUIRED OPTIONAL Link Capacity REQUIRED OPTIONAL
Link Availability OPTIONAL OPTIONAL Link Availability OPTIONAL OPTIONAL
Diversity Support OPTIONAL OPTIONAL Diversity Support OPTIONAL OPTIONAL
Local Adaptation support OPTIONAL OPTIONAL Local Adaptation support OPTIONAL OPTIONAL
Table 3. TE link Characteristics Table 3. TE link Characteristics
W.Alanqar et al. - Expires May 2004 9
Note: separate advertisements of layer specific attributes MAY be Note: separate advertisements of layer specific attributes MAY be
chosen. However this may lead to unnecessary duplication. This can chosen. However this may lead to unnecessary duplication. This can
be avoided using the inheritance property, so that attributes be avoided using the inheritance property, so that attributes
derivable from the local adaptation information do not need to be derivable from the local adaptation information do not need to be
advertised. advertised.
5. Backward Compatibility 5. Backward Compatibility
Any particular realization of the ASON routing requirements MUST be Any particular realization of the ASON routing requirements MUST be
backward compatible with the considered routing protocol(s). backward compatible with the considered routing protocol(s).
Backward compatibility means that at any level of the routing Backward compatibility means that at any level of the routing
hierarchy, nodes, some of which support the requirements described hierarchy, nodes, some of which support the requirements described
in this document, and some of which do not, must still be capable to in this document, and some of which do not, MUST still be capable to
operate as mandated by the OSPF, IS-IS, and/or IDR IETF WG and their operate as mandated by the OSPF, IS-IS, and/or IDR IETF WG and their
corresponding GMPLS extensions (as mandated by the CCAMP IETF WG). corresponding GMPLS extensions (as mandated by the CCAMP IETF WG).
Additionally, nodes (that do not support these requirements) are Additionally, nodes (that do not support these requirements and) are
made part of a multi-level routing hierarchy from their containing made part of a multi-level routing hierarchy from their containing
RA(s), must be capable of: RA(s), must be capable of:
- rejecting any incoming routing information that would be - rejecting (or ignoring) any incoming routing information that
addressed to them in a way that is not detrimental to the would be addressed to them in a way that is not detrimental to the
network as a whole network as a whole
- communicating (at a given level) with any other node located - communicating (at a given level) with any other node located
at the same level and that implements these requirements at the same level and that implements these requirements
This assumes that such nodes do not communicate directly either with This assumes that such nodes do not communicate directly either with
lower or upper level nodes. lower or upper level nodes.
Note: backward compatibility with routing protocols is a protocol
requirement defined in the IETF context.
W.Alanqar et al. - Expires July 2004 10
6. Security Considerations 6. Security Considerations
TBD. ASON routing protocol MUST deliver the operational security
objectives where required.
7. Acknowledgements 7. Conclusions
This section captures from the identified ASON routing requirements
the missing capabilities from the GMPLS routing protocols (e.g.
OSPF, IS-IS).
The GMPLS routing protocol is required to support multiple
hierarchical levels of RAs and hierarchical routing information
dissemination including summarized routing information. However, the
number of hierarchical levels to be supported is routing protocol
implementation specific. This implies that the GMPLS routing
protocol must deliver:
- processing of routing information exchanged between adjacent
levels of the routing hierarchy (i.e. Level N+1 and N) including
reachability and upon policy decision summarized topology
information
- when multiple RCs within a RA transform (filter, summarize, etc.)
and then forward information to RC(s) at different levels that the
resulting information at the receiving level is self-consistent
- a mechanism to prevent re-introduction of information propagated
into the Level N RA back to the external level RA from which this
information has been initially received. It is thus expected that
advertisements will include information when they have been
derived from a source external to the RA. Note that existing
routing protocols support mechanisms to identify advertisements of
externally derived information and therefore an analysis of their
applicability has to be considered on a per-protocol basis.
In order to support operator assisted changes in the containment
relationships of RAs, the GMPLS routing protocol is expected to
support evolution in terms of number of hierarchical levels of RAs
(adding and removing RAs at the top/bottom of the hierarchy), as
well as aggregation and segmentation of RAs. These GMPLS routing
capabilities are considered of lower priority as they are
implementation specific and their method of support should be
evaluated on per-protocol basis e.g. OSPF vs IS-IS. In addition,
support of non-disruptive operations such as adding or removing a
hierarchical level of RAs in or from the middle of the routing
hierarchy are considered as the lowest priority requirements. Note
also that the number of hierarchical levels to be supported is
implementation specific, and reflects a containment relationship
e.g. a RA insertion involves supporting a different routing protocol
domain in a portion of the network.
Note: some members of the Design Team question if the ASON
requirement for supporting architecture evolution is a requirement
on the routing protocol (protocol-specific capability) vs. a
W.Alanqar et al. - Expires July 2004 11
capability to be provided by the architecture. For example, ASON
allows for supporting multiple protocols within each RA. The
multiple protocols share a common routing information database
(RDB), and the RDB is the component, which needs to support
architecture evolution. The Design Team invites CCAMP input to
understand the protocol-specific impacts.
GMPLS routing currently covers all node attributes considered in
[G.7715.1]. Assuming that the set of TE link IDs are numbered either
from their component/TE links or from the node address that hosts
these components/TE links, no additional extensions seem to be
required in order to advertise reachable end-points within an ASON
control plane. Advertisement of externally reachable prefixes is
built in within any routing protocol independently of its usage
in/outside GMPLS.
Note: some members of the Design Team noted that reachability
information (as described in Section 4.5.3) may be advertised as a
set of UNI Transport Resource address prefixes (assigned and
selected consistently in their applicability scope). These members
of the Design Team raised a concern that existing methods of
advertising reachability may need to be examined (on a per-protocol
basis) to determine if they are also applicable for UNI Transport
Resource addresses. They invite CCAMP discussion on this aspect.
From the considered list of link attributes and characteristics, the
Local Adaptation support information is missing as TE link
attribute. GMPLS routing does not currently consider the use of
dedicated TE link attribute(s) to describe the cross/inter-layer
relationships. All other TE link attributes and characteristics are
currently covered. The need for a "TE metric" per component link
needs to be further assessed, in the sense that it can be currently
implemented. Further consideration is here needed regarding impacts
on TE link bundling capabilities and the increase of the routing
advertisement overhead with potentially duplicated information.
Note: ASON does not restrict the architecture choices used, either a
co-located architecture or a physically separated architecture may
be used. Some members of the Design Team are concerned that GMPLS's
concept of the LSR requires a 1-to-1 relationship between the
transport plane entity and the control plane entity (Router). They
invite CCAMP input on GMPLS capabilities to support multiple
architectures i.e. how routing protocols would identify the
transport node ID vs. the router or routing controller ID when
scoping Link IDs in a link advertisement.
The inheritance property of link attributes used to optimize the
component/TE link configuration process is built in within GMPLS.
W.Alanqar et al. - Expires July 2004 12
8. Acknowledgements
The authors would like to thank Kireeti Kompella for having The authors would like to thank Kireeti Kompella for having
initiated the proposal of an ASON Routing Requirement Design Team. initiated the proposal of an ASON Routing Requirement Design Team.
8. Intellectual Property Considerations 9. Intellectual Property Considerations
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances claims of rights made available for publication and any assurances
of licenses to be made available, or the result of an attempt made of licenses to be made available, or the result of an attempt made
to obtain a general license or permission for the use of such to obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification proprietary rights by implementors or users of this specification
can be obtained from the IETF Secretariat. can be obtained from the IETF Secretariat.
W.Alanqar et al. - Expires May 2004 10
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive this standard. Please address the information to the IETF Executive
Director. Director.
9. References 10. References
10.1 Normative References
[RFC 2026] S.Bradner, "The Internet Standards Process -- [RFC 2026] S.Bradner, "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996. Revision 3", BCP 9, RFC 2026, October 1996.
[RFC 2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC 2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and [G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
Requirements for the Automatically Switched Optical Requirements for the Automatically Switched Optical
Network (ASON)," June 2002. Network (ASON)," June 2002.
skipping to change at line 563 skipping to change at line 693
Protocols," November 2003. Protocols," November 2003.
[G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the [G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON)," Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003). November 2001 (and Revision, January 2003).
[HIER] K.Kompella and Y.Rekhter, "LSP Hierarchy with [HIER] K.Kompella and Y.Rekhter, "LSP Hierarchy with
Generalized MPLS TE," Internet draft (work in Generalized MPLS TE," Internet draft (work in
progress), draft-ietf-mpls-lsp-hierarchy, Sept'02. progress), draft-ietf-mpls-lsp-hierarchy, Sept'02.
10. Author's Addresses W.Alanqar et al. - Expires July 2004 13
11. Author's Addresses
Wesam Alanqar (Sprint) Wesam Alanqar (Sprint)
EMail: wesam.alanqar@mail.sprint.com EMail: wesam.alanqar@mail.sprint.com
Deborah Brungard (AT&T) Deborah Brungard (AT&T)
Rm. D1-3C22 - 200 S. Laurel Ave. Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA Middletown, NJ 07748, USA
Phone: +1 732 4201573 Phone: +1 732 4201573
EMail: dbrungard@att.com EMail: dbrungard@att.com
David Meyer (Cisco Systems) David Meyer (Cisco Systems)
EMail: dmm@1-4-5.net EMail: dmm@1-4-5.net
Lyndon Ong (Ciena Corporation) Lyndon Ong (Ciena Corporation)
5965 Silver Creek Valley Rd, 5965 Silver Creek Valley Rd,
San Jose, CA 95128, USA San Jose, CA 95128, USA
Phone: +1 408 8347894 Phone: +1 408 8347894
EMail: lyong@ciena.com EMail: lyong@ciena.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
W.Alanqar et al. - Expires May 2004 11
Francis Wellensplein 1, Francis Wellensplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Phone: +32 3 2408491 Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be EMail: dimitri.papadimitriou@alcatel.be
Jonathan Sadler Jonathan Sadler
1415 W. Diehl Rd 1415 W. Diehl Rd
Naperville, IL 60563 Naperville, IL 60563
EMail: jonathan.sadler@tellabs.com EMail: jonathan.sadler@tellabs.com
Stephen Shew (Nortel Networks) Stephen Shew (Nortel Networks)
PO Box 3511 Station C PO Box 3511 Station C
Ottawa, Ontario, CANADA K1Y 4H7 Ottawa, Ontario, CANADA K1Y 4H7
Phone: +1 613 7632462 Phone: +1 613 7632462
EMail: sdshew@nortelnetworks.com EMail: sdshew@nortelnetworks.com
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Appendix 1 - ASON Terminology Appendix 1 - ASON Terminology
This document makes use of the following terms: This document makes use of the following terms:
Administrative domain: See Recommendation G.805. Administrative domain: See Recommendation G.805.
Control plane: performs the call control and connection control Control plane: performs the call control and connection control
functions. Through signaling, the control plane sets up and releases functions. Through signaling, the control plane sets up and releases
connections, and may restore a connection in case of a failure. connections, and may restore a connection in case of a failure.
skipping to change at line 646 skipping to change at line 776
Transport plane: provides bi-directional or unidirectional transfer Transport plane: provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also of user information, from one location to another. It can also
provide transfer of some control and network management information. provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport The Transport Plane is layered; it is equivalent to the Transport
Network defined in G.805. Network defined in G.805.
User Network Interface (UNI): interfaces are located between User Network Interface (UNI): interfaces are located between
protocol controllers between a user and a control domain. protocol controllers between a user and a control domain.
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Appendix 2 - ASON Routing Terminology Appendix 2 - ASON Routing Terminology
This document makes use of the following terms: This document makes use of the following terms:
Routing Area (RA): represents functionally either an Autonomous Routing Area (RA): a RA represents a partition of the data plane and
System (AS) or a canonical IGP routing area, both are sometimes its identifier is used within the control plane as the
referred to as routing regions (or simply regions). representation of this partition. Per [G.8080] a RA is defined by a
set of sub-networks, the TE links that interconnect them, and the
interfaces representing the ends of the TE links exiting that RA. A
RA may contain smaller RAs inter-connected by TE links. The limit of
subdivision results in a RA that contains two sub-networks and a TE
link with a single component link.
Routing Database (RDB): repository for the local topology, network Routing Database (RDB): repository for the local topology, network
topology, reachability, and other routing information that is topology, reachability, and other routing information that is
updated as part of the routing information exchange and may updated as part of the routing information exchange and may
additionally contain information that is configured. The RDB may additionally contain information that is configured. The RDB may
contain routing information for more than one Routing Area (RA). contain routing information for more than one Routing Area (RA).
Routing Components: ASON routing architecture functions. These Routing Components: ASON routing architecture functions. These
functions can be classified as protocol independent (Link Resource functions can be classified as protocol independent (Link Resource
Manager or LRM, Routing Controller or RC) and protocol specific Manager or LRM, Routing Controller or RC) and protocol specific
(Protocol Controller or PC). (Protocol Controller or PC).
- Routing Controller (RC): handles (abstract) information needed for Routing Controller (RC): handles (abstract) information needed for
routing and the routing information exchange with peering RCs by routing and the routing information exchange with peering RCs by
operating on the RDB. The RC has access to a view of the RDB. The RC operating on the RDB. The RC has access to a view of the RDB. The RC
is protocol independent. is protocol independent.
Note: Since the RDB may contain routing information pertaining to Note: Since the RDB may contain routing information pertaining to
multiple RAs (and hence possibly multiple layer networks), the RCs multiple RAs (and hence possibly multiple layer networks), the RCs
accessing the RDB may share the routing information. accessing the RDB may share the routing information.
- Link Resource Manager (LRM): supplies all the relevant component Link Resource Manager (LRM): supplies all the relevant component
and TE link information to the RC. It informs the RC about any state and TE link information to the RC. It informs the RC about any state
changes of the link resources it controls. changes of the link resources it controls.
- Protocol Controller (PC): handles protocol specific message Protocol Controller (PC): handles protocol specific message
exchanges according to the reference point over which the exchanges according to the reference point over which the
information is exchanged (e.g. E-NNI, I-NNI), and internal exchanges information is exchanged (e.g. E-NNI, I-NNI), and internal exchanges
with the RC. The PC function is protocol dependent. with the RC. The PC function is protocol dependent.
Internal Links: links that are fully encapsulated by a routing area W.Alanqar et al. - Expires July 2004 16
at a given level of hierarchy. Internal links to a child RA may be
hidden from the parent RAs view.
External Links: links that are incident upon the routing area. Note
that external links to a routing area at one level of the hierarchy
may be internal links in the parent routing area.
W.Alanqar et al. - Expires May 2004 14
Full Copyright Statement Full Copyright Statement
"Copyright (C) The Internet Society (2003). All Rights Reserved. "Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
skipping to change at line 723 skipping to change at line 850
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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 End of changes. 

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