wdiff draft-ietf-ccamp-gmpls-ason-routing-reqts-02.txt draft-ietf-ccamp-gmpls-ason-routing-reqts-03.txt

CCAMP Working Group Wesam Alanqar (Sprint)
Internet Draft Deborah Brungard (ATT)
Category: Informational Dave David Meyer (Cisco Systems)
Lyndon Ong (Ciena)
Expiration Date: July October 2004 Dimitri Papadimitriou (Alcatel)
Jonathan Sadler (Tellabs)
Stephen Shew (Nortel)

February

April 2004

Requirements for Generalized MPLS (GMPLS) Routing
for Automatically Switched Optical Network (ASON)

draft-ietf-ccamp-gmpls-ason-routing-reqts-02.txt

draft-ietf-ccamp-gmpls-ason-routing-reqts-03.txt

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC-2026.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts. Internet-Drafts are draft documents valid for a maximum of
six months and may be updated, replaced, or obsoleted by other
documents at any time. It is inappropriate to use Internet- Drafts
as reference material or to cite them other than as "work in
progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Abstract

The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different
applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs).

This document concentrates on the routing requirements on the GMPLS
suite of protocols to support the capabilities and functionalities
for an Automatically Switched Optical Network (ASON) as defined by
ITU-T.

W.Alanqar et al. - Expires July September 2004 1

Table of Contents

Status of this Memo .............................................. 1
Abstract ......................................................... 1
1. Contributors .................................................. 2
2. Conventions used in this document ............................. 2
3. Introduction .................................................. 2
4. ASON Routing Architecture and Requirements .................... 4
4.1 Multiple Hierarchical Levels of ASON Routing Areas (RAs) ..... 5
4.2 Hierarchical Routing Information Dissemination ............... 5
4.3 Configuration ................................................ 7
4.3.1 Configuring the Multi-Level Hierarchy ...................... 7
4.3.2 Configuring RC Adjacencies ................................. 7
4.4 Evolution .................................................... 7
4.5 Routing Attributes ........................................... 8
4.5.1 Taxonomy of Routing Attributes ............................. 8
4.5.2 Commonly Advertised Information ............................ 9
4.5.3 Node Attributes ............................................ 9
4.5.4 Link Attributes ............................................ 9
5. Security Considerations ...................................... 11
6. Conclusions .................................................. 11
7. Acknowledgements ............................................. 13
8. Intellectual Property Considerations ......................... 13
8.1 IPR Disclosure Acknowledgement .............................. 13
9. References ................................................... 14
9.1 Normative References ........................................ 14
10. Author's Addresses .......................................... 14
Appendix 1: ASON Terminology .................................... 16
Appendix 2: ASON Routing Terminology ............................ 18
Full Copyright Statement ........................................ 19

1. Contributors

This document is the result of the CCAMP Working Group ASON Routing
Requirements design team joint effort.

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119. RFC 2119
[RFC2119].

3. Introduction

The GMPLS suite of protocols provides among other capability capabilities
support for controlling different switching technologies. These
include support for requesting TDM connections utilizing SONET/SDH
(see ANSI T1.105/ITU-T G.707) as well as Optical Transport Networks (see
(OTN, see ITU-T G.709). However, there are certain capabilities that
are needed to support the ITU-T G.8080 control plane architecture
for the Automatically Switched Optical Network (ASON). Therefore, it is

W.Alanqar et al. - Expires October 2004 2
desirable to understand the corresponding requirements for the GMPLS
protocol suite. The ASON control plane architecture is defined in
[G.8080] and
[G.8080], ASON routing requirements are identified in [G.7715] [G.7715], and refined
in [G.7715.1] for ASON link state architectures. protocols. These
recommendations provide functional requirements Recommendations
apply to all G.805 layer networks (e.g. SDH and OTN), and architecture,
they provide a
protocol neutral approach. functional requirements and architecture.

This document focuses on the routing requirements for the GMPLS
suite of protocols to support the capabilities and functionality of
ASON control planes. It discusses This document summarizes the ASON requirements for
using ASON terminology. This document does not address GMPLS routing
that MAY subsequently lead to additional backward compatible
extensions to support the capabilities specified in the above
referenced documents. A description of backward compatibility
considerations is provided in Section 5. Nonetheless, any
applicability or GMPLS capabilities. Any protocol (in particular,
routing) applicability, design or suggested protocol extensions is strictly
outside the scope of this document. An ASON (Routing) terminology section is
sections are provided in Appendix 1 and Appendix 2.

The ASON model distinguishes reference points (representing points
of information exchange) defined (1) between an administrative
domain routing architecture is based on the following assumptions:
- A network is subdivided based on operator decision and a user (user-network interface or UNI), (2) between
administrative domains or within an administrative domain between
different control domains (external network-network interface or E-
NNI) and, (3) within criteria
(e.g. geography, administration, and/or technology), the same administrative domain between control
components (or simply controllers) of the same control domain
(internal network-network interface or I-NNI). The ASON model allows
for the protocols used within different control domains to be
different; and for the protocol used between control domains to be
different than the protocols used within control domains. I-NNI
control interfaces are located between protocol controllers within a
control domain. E-NNI control interfaces are located on protocol
controllers between control domains.

W.Alanqar et al. - Expires July 2004 2
The term routing information refers to the abstract representation
of network routing related information such
subdivisions are defined in ASON as node and link
attributes (see Section 4.5). No routing information is passed over
the UNI. Routing information exchanged over the NNI is subject to
the policy constraints at individual NNIs. The routing information
exchanged over the E-NNI encapsulates the common semantics of the
individual domain information while allowing different
representation within each domain. Areas (RAs).
- The ASON routing architecture is based on and protocols applied after the following assumptions:
- A carrier's network
is subdivided is an operator's choice. A multi-level hierarchy of
RAs, as Routing Areas (RAs). Each RA
shall be uniquely identifiable defined in ITU-T [G.7715] and [G.7715.1], provides for a
hierarchical relationship of RAs based on containment, i.e. child
RAs are always contained within a carrier's network (i.e.
administrative domain). parent RA. The hierarchical
containment relationship of RAs partitioning provide provides for routing information
abstraction, thereby enabling scalable routing.
- Routing Controllers (RC) provide for the exchange of routing information between and within a RA. The routing information
exchanged between RCs is subject to policy constraints imposed at
reference points (E-NNI and I-NNI).
- For a RA, the set of RCs is referred to as a routing (control)
domain. The RC MAY support more than one routing protocol (i.e. an
RC MAY support multiple Protocol Controller (PCs)). There SHOULD
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
protocol and the intra-domain control distribution choice(s), e.g.
centralized, fully distributed.
- The routing adjacency topology (i.e. the associated PC
connectivity topology) and the transport network topology SHALL
NOT be assumed to be congruent.
representation. The following functionality is expected from GMPLS routing to
instantiate ASON routing realization (see [G.7715] and [G.7715.1]):
- support multiple hierarchical levels of RAs; the maximum number of hierarchical RA levels to be
supported is routing protocol
implementation specific.
- support hierarchical routing information dissemination including
summarized routing information NOT specified (outside the scope).
- support for multiple links between nodes (and between RAs) Within an ASON RA and for
link and node diversity
- support architectural evolution in terms each level of the number of levels
of hierarchies, aggregation routing hierarchy,
multiple routing paradigms (hierarchical, step- by-step, source-
based), centralized or distributed path computation, and segmentation of RAs
- support multiple
different routing information based on protocols MAY be supported. The architecture
does NOT assume a common set one-to-one correspondence of information
elements as defined in [G.7715] and [G.7715.1], divided between
attributes pertaining to links and abstract nodes (each
representing either a sub-network or simply a node). [G.7715]
recognizes that the manner in which the routing information is
represented and exchanged will vary with the routing protocol
used.

Also,
and a RA level and allows the behaviour of GMPLS routing is expected protocol(s) used within
different RAs (including child and parent RAs) to be such that:
- it is scalable with respect different.
The realization of the routing paradigm(s) to support the number
hierarchical levels of links, nodes and RAs is NOT specified.
- in response to a The routing event (e.g. adjacency topology update, reachability

W.Alanqar et al. - Expires July 2004 3
update), it delivers convergence (i.e. the associated Protocol
Controller (PC) connectivity) and damping against flapping transport topology is NOT
assumed to be congruent.
- it fulfils The requirements support architectural evolution, e.g. a change in
the operational security objectives where required

4. ASON Requirements for GMPLS Routing number of RA levels, as well as aggregation and segmentation
of RAs.

The description of the ASON routing architecture provides for a
conceptual reference architecture, with definition of functional
components (see Appendix 2) is
provided and common information elements to enable end-to-end
routing in terms the case of routing functionality. protocol heterogeneity and facilitate
management of ASON networks. This description is only conceptual: no
physical partitioning of these functions is implied.

W.Alanqar et al. - Expires October 2004 3

4. ASON Routing Architecture and Requirements

The fundamental architectural concept is the RA and it's related
functional components (see Appendix 2 on terminology). The routing
services offered by a RA are provided by a Routing Performer (RP).
An RP is responsible for a single RA, and it MAY be functionally
realized using distributed Routing Controllers (RC). The RC, itself,
MAY be implemented as a cluster of distributed entities (ASON refers
to the cluster as a Routing Controller (RC) Control Domain (RCD)). The RC components
for a RA receive routing topology information from their associated
Link Resource Manager(s) (LRMs) regarding TE
links and store this information in the
Routing Information Database (RDB). The RDB is replicated at each RC within
bounded to the same Routing Area (RA), and MAY contain information
about multiple transport plane network layers. Whenever the state of a TE link (or component link) routing
topology changes, the LRM informs the corresponding RC, which in
turn updates its associated RDB. In order to assure RDB
synchronization, the RCs co-operate and exchange routing
information. Path computation functions MAY exist in each RC, MAY
exist on selected RCs within the same RA, or MAY be centralized for
the RA.

In this context, communication between RCs within the same RA is
realized using a particular routing protocol (or multiple
protocols). In ASON, the communication component is represented by
the protocol controller (PC) component component(s) and the protocol messages
are conveyed over the ASON control plane's Signaling Control Network
(SCN). The PC MAY convey information for one or more transport
network layers. Moreover, as [G7715.1] states layers (refer to Section 4.2 Note). The RC is protocol
independent and
illustrates in its Figure 1, RC communications MAY be realized by multiple,
different PCs within a RA.

The ASON routing architecture defines a multi-level routing
hierarchy of RAs based on a containment model to support routing
information abstraction. [G.7715.1] defines the ASON hierarchical
link state routing protocol requirements
deals exclusively with the PC to PC for communication of the (RC)
routing information; therefore any information within an RA (one level) to support hierarchical
routing information dissemination (including summarized routing
information for other communication levels). The Communication between any of the
other functional component(s) (e.g. SC, LRM) SCN, LRM, and between RCDs (RC-
RC communication between RAs)), is outside the scope of [G.7715.1]
protocol requirements and, thus, is also outside the scope of this
document.

Note: the RC can be thought of as the function processing the TE
database populated

ASON Routing components are identified by the link local/remote component and TE links
(LRM) identifiers that are drawn
from different name spaces (see [G.7715.1]). These are control plane
identifiers for transport resources, components, and by the network wide TE links through the PC which
processes the SCN addresses.
The formats of those identifiers in a routing protocol realization
SHALL be implementation specific routing exchanges. and outside the scope of this
document.

The SCN
corresponds to failure of a RC, or the IP control plane topology enabling routing
exchanges failure of communications between GMPLS controllers (i.e. RCs,
and the routing adjacencies). subsequent recover from the failure condition MUST NOT

W.Alanqar et al. - Expires October 2004 4
disrupt calls in progress and their associated connections. Calls
being set up MAY fail to complete, and the call setup service MAY be
unavailable during recovery actions.

4.1 Multiple Hierarchical Levels of ASON Routing Areas (RAs)

[G.8080] introduces the concept of Routing Area (RA). (RA) in reference to
a network subdivision. RAs provide for routing information abstraction, thereby enabling scalable
routing information representation.
abstraction. Except for the single RA case, RAs are hierarchically
contained: a higher level (parent) RA contains lower level (child)
RAs that in turn MAY also contain RAs, etc. Thus, RAs contain RAs
that recursively define successive hierarchical routing RA levels.

However, the RA containment relationship describes only an
architectural hierarchical organization of RAs. It does not restrict
the
a specific routing protocol protocol's realization (e.g. OSPF multi-areas,
path computation, etc.). Moreover, the realization of the routing
paradigm to support a hierarchical routing organization of RAs and the
number of

W.Alanqar et al. - Expires July 2004 4 hierarchical RA 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
from several identifier spaces (see [G.7715.1]). The use of
identifiers in a routing protocol realization is implementation
specific and outside the scope of this document.

In a multi-level routing hierarchy, hierarchy of RAs, it is necessary to distinguish
among RCs within a level and RCs at for the different levels of the routing RA hierarchy. Before any
pair of RCs establishes communication, they MUST verify they belong are
bounded to the same parent RA (see Section 4.2). A RA identifier (RA
ID) is required to provide the scope within which the RCs can
communicate. To distinguish between RCs within bounded to the same RA, an
RC identifier (RC ID) is required; the RC ID must MUST be unique within
its containing RA.

A RA represents a partition of the data plane and its identifier
(i.e. RA ID) is used within the control plane as a reference to the
data plane partition. Each RA SHALL be uniquely identifiable within
a carrier's network. 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

Routing information can be exchanged between RCs bounded to adjacent
levels of the
routing RA 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 as external links, links (inter-RA links), and the links
representing connectivity within an a RA MAY be viewed as internal links.
links (intra-RA links). The external links to a RA at one level of
the hierarchy may be internal links in the parent RA. Intra-RA links
of a child RA MAY be hidden from the parent RA's view.

The physical location of RCs at for adjacent RA levels, their
relationship and their communication protocol protocol(s) are outside the
scope of this document. No assumption is made regarding how RCs
communicate between adjacent RA levels. If routing information is

W.Alanqar et al. - Expires October 2004 5
exchanged between a RC, its parent, and its child RCs, it SHOULD
include reachability and MAY include (upon policy decision) node and
link topology.

Multiple Only the RCs of the parent RA communicate, RCs of one
child�s RA never communicate with the RCs of other child RAs. There
SHOULD not be any dependencies on the different routing protocols
used within a RA or in different RAs.

Multiple RCs bounded to the same RA MAY transform (filter,
summarize, etc.) and then forward information to RCs at different
levels. However in this case the resulting information at the
receiving level must be self-
consistent; self-consistent; this MAY be achieved using
a number of mechanisms.

Note: there is no implied relationship between multi-layer transport
networks and multi-level routing. The former implies Implementations may support a
hierarchical routing topology (multi-level) with a single routing
protocol instance for multiple transport switching layers whereas the latter implies or a
hierarchical routing topology for one transport switching layer.

4.2.1 Communication between Adjacent Routing Levels

1. Type of Information Exchanged

W.Alanqar et al. - Expires July 2004 5

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
Level N) are used for similar purposes, namely, the exchange of
reachability information and summarized topology information to
allow routing across multiple RAs. The summarization of topology
information may impact the accuracy of routing and MAY require
additional path calculation.

The following information exchange are expected:

- Level N+1 visibility to Level N reachability and topology (or
upward information communication) allowing RC(s) at level Level N+1
to determine the reachable endpoints from Level N.
- Level N visibility to Level N+1 reachability and topology (or
downward information communication) allowing RC(s) in an bounded to a
RA at Level N to develop paths to reachable endpoints outside
of the RA.

2. Interactions between Upward and Downward Communication

When both upward and downward information exchanges contain
endpoint reachability information, a feedback loop could
potentially be created. Consequently, the routing protocol MUST
include a method to:

- prevent information propagated from a Level N+1 RA RA's RC into
the Level N RA RA's RC to be re-introduced into the Level N+1 RA, RA's
RC, and

- prevent information propagated from a Level N-1 RA RA's RC into
the Level N RA RA's RC to be re-introduced into the Level N-1 RA. RA's

W.Alanqar et al. - Expires October 2004 6
RC.

The routing protocol is required to SHALL differentiate the routing information
originated at a given level RA from the one derived
using the routing information received
(received from its external RAs
(regardless of the level of RAs), even when this information is
forwarded by another RC at the corresponding RCs). same level. This is a necessary
condition to be fulfilled by routing protocols to be loop free.

Also, for ASON, the routing information exchange may generate
transient loops at the data plane if no route recording is used
during signaling. So, at the data plane, it is not the routing
exchange that guarantees (transient) loop avoidance but the
signaling protocol by recording the route until the node where
computation occurs (by excluding segments already traversed).

3. Method of Communication

Two approaches exist for communication between Level N and N+1.

- The first approach places an instance of a Level N routing
function and an instance of a Level N+1 routing function in the
same system. The communications interface is within a single
system and is thus not an open interface subject to
standardization.

W.Alanqar et al. - Expires July 2004 6

- The second approach places the Level N routing function on a
separate system from the Level N+1 routing function. In this
case, a communication interface must be used between the
systems containing the routing functions for different levels.
This communication interface and mechanisms are outside the
scope of this document.

4.2.2

4.3 Configuration

4.3.1 Configuring the Routing Multi-Level Hierarchy

The RC MUST support static (i.e. operator assisted) and MAY support
automated configuration of the information describing its
relationship to parent and its child within the hierarchical routing
structure (including RA ID and RC ID). When applied recursively, the
whole hierarchy is thus configured.

4.2.3

4.3.2 Configuring RC Adjacencies

The RC MUST support static (i.e. operator assisted) and MAY support
automated configuration of the information describing its control associated
PC adjacencies to other RCs within a bounded to the same parent RA. The
routing protocol SHOULD support all the types of RC adjacencies
described in Section 9 of [G.7715]. The latter includes congruent
topology (with distributed RC) and hubbed topology (with (e.g. note that
the latter does not automatically imply designated RC).

4.3

4.4 Evolution

The containment relationships of RAs MAY change, motivated by events
such as mergers, acquisitions, and divestitures.

The routing protocol SHOULD be capable of supporting architectural
evolution in terms of number of hierarchical levels, levels of RAs, as well

W.Alanqar et al. - Expires October 2004 7
as aggregation and segmentation of RAs. RA IDs uniqueness within an
administrative domain MAY facilitate these operations. The routing
protocol is not expected to automatically initiate and/or execute
these operations.

4.4 Multiple Links between Nodes Reconfiguration of the RA hierarchy MAY not
disrupt calls in progress, though calls being set up may fail to
complete, and RAs

See Section 4.5.1 the call setup service may be unavailable during
reconfiguration actions.

4.5 Routing Attributes

Routing for transport networks is performed on a per layer basis,
where the routing paradigms MAY differ among layers and within a
layer. Not all equipment support the same set of transport layers or
the same degree of connection flexibility at any given layer. A
server layer trail may support various clients, involving different
adaptation functions. Additionally, equipment may support variable
adaptation functionality, whereby a single server layer trail
dynamically supports different multiplexing structures. As a result,
routing information MAY include layer specific, layer independent,
and client/server adaptation information.

W.Alanqar et al. - Expires July 2004 7

4.5.1 Taxonomy of Routing Attributes

Attributes can be organized according to the following categories:

- Node related or link related

- Provisioned, negotiated or automatically configured

- Inherited or layer specific (client layers can inherit some
attributes from the server layer while other attributes like
Link Capacity are specified by layer).

(Component) link attributes can MAY be statically or automatically
configured for each transport network layer. This may lead to
unnecessary repetition. Hence, the inheritance property of
attributes can MAY also be used to optimize the configuration process.

TE links are configured through

ASON uses the term, SNP, for the control plane representation of a
transport plane resource. The control plane representation and
transport plane topology is NOT assumed to be congruent, the control
plane representation SHALL not be restricted by the physical
topology. The relational grouping of component SNPs for routing is termed a
SNPP. The routing function understands topology in terms of SNPP
links. Grouping MAY be based on different link attributes (e.g.,
SRLG information, link weight, etc).

Two RAs may be linked by one or more TE SNPP links. Multiple TE SNPP links may
MAY be required when component links are not equivalent for routing
purposes with respect to the RAs they are attached to, or to the
containing RA, or when smaller groupings are required.

W.Alanqar et al. - Expires October 2004 8

4.5.2 Commonly Advertised Information

Advertisements MAY contain the following common set of information
regardless of whether they are link or node related:
- RA ID of which the advertisement is bounded
- RC ID of the entity generating the advertisement
- Information to uniquely identify advertisements
- Information to determine whether an advertisement has been updated
- Information to indicate when an advertisement has been derived
from a source external to the routing area different level RA.

4.5.3 Node Attributes

All nodes belong to a RA, hence hence, the RA ID can be considered an
attribute of all nodes. Given that no distinction is made between
abstract nodes and those that cannot be decomposed any further, the
same attributes MAY be used for their advertisement. In the
following tables, Capability refers to level of support required in
the realization of a link state routing protocol, whereas Usage
refers to degree of operational and implementation flexibility.

The following Node Attributes are defined:

Attribute Capability Usage
----------- ----------- ---------
Node ID REQUIRED REQUIRED
Reachability REQUIRED OPTIONAL

Table 1. Node Attributes

W.Alanqar et al. - Expires July 2004 8

Reachability information describes the set of endpoints that are
reachable by the associated node. It MAY be advertised as a set of
associated address external (e.g. UNI) address/address prefixes or a set of
associated TE SNPP link IDs,
consistently assigned IDs/SNPP ID prefixes, the selection of which
MUST be consistent within an administrative domain. the applicable scope. These are control
plane identifiers, the formats of these identifiers in a protocol
realization is implementation specific and outside the scope of this
document.

Note: no distinction is made between nodes that may have further
internal details (i.e., abstract nodes) and those that cannot be
decomposed any further. Hence the attributes of a node are not be
considered only as single switch attributes but MAY apply to a node
at a higher level of the hierarchy that represents a sub-network.

4.5.4 Link Attributes

The following Link Attributes are defined:

Link Attribute Capability Usage
--------------- ----------- ---------
Local TE SNPP link ID REQUIRED REQUIRED

W.Alanqar et al. - Expires October 2004 9
Remote TE SNPP link ID REQUIRED REQUIRED
TE Link
Layer Specific Characteristics see Table 3

Table 2. Link Attributes

The TE SNPP link ID must name MUST be sufficient to uniquely identify the
corresponding transport plane resource taking into account
separation of data and control planes. control planes (see Section 4.5.1, the
control plane representation and transport plane topology is not
assumed to be congruent). The TE SNPP link ID format is routing
protocol specific.

Note: when the remote end of a TE SNPP link is located outside of the
RA, the remote TE SNPP link ID is OPTIONAL.

The following TE link characteristic attributes are defined:

- Signal Type: This identifies the characteristic information of the
layer network.

- Link Weight: The metric indicating the relative desirability of a
particular link over another e.g. during path computation.

- Resource Class: This corresponds to the set of administrative
groups assigned by the operator to this link. A link MAY belong to
zero, one or more administrative groups.

- Connection Types: This allows identification of attribute identifies whether the local
component link is at SNP
represents a border TCP, CP, or within an LSP region (see [HIER]) can be flexibly configured as a TCP.

- Link Capacity: This provides the sum of the available and
potential bandwidth capacity for a particular network transport
layer. Other capacity measures MAY be further considered.

- Link Availability: This represents the survivability capability
such as the protection type associated with the link.

- Diversity Support: This represents diversity information such as

W.Alanqar et al. - Expires July 2004 9
the SRLG information associated with the link.

- Local Adaptation Support: This indicates the set of client layer
adaptations supported by the local component link TCP associated to with the local TE link. Local SNPP.
This can is only exist applicable when the "Local Connection
Type" indicates crossing of an LSP Region local SNP represents a TCP or can
be flexibly
assigned to be at configured as a border or within an LSP region (see [HIER]).

TE link TCP.

Link Characteristics Capability Usage
----------------------- ---------- ---------
Signal Type REQUIRED OPTIONAL
Link Weight REQUIRED OPTIONAL
Resource Class REQUIRED OPTIONAL
Local Connection Types REQUIRED OPTIONAL
Link Capacity REQUIRED OPTIONAL

W.Alanqar et al. - Expires October 2004 10
Link Availability OPTIONAL OPTIONAL
Diversity Support OPTIONAL OPTIONAL
Local Adaptation support OPTIONAL OPTIONAL

Table 3. TE link Link Characteristics

Note: separate advertisements of layer specific attributes MAY be
chosen. However this may lead to unnecessary duplication. This can
be avoided using the inheritance property, so that the attributes
derivable from the local adaptation information do not need to be
advertised. Thus, an optimization MAY be used when several layers
are present by indicating when an attribute is inheritable from a
server layer.

5. Backward Compatibility

Any particular realization Security Considerations

ASON routing protocol MUST deliver the operational security
objectives where required. These objectives do not necessarily imply
requirements on the routing protocol itself, and MAY be met by other
established means.

6. Conclusions

The description of the ASON routing architecture and components is
provided in terms of routing functionality. This description is only
conceptual: no physical partitioning of these functions is implied.

In summary, the ASON routing architecture assumes:
- A network is subdivided into ASON RAs, which MAY support multiple
routing protocols, no one-to-one relationship SHALL be assumed
- Routing Controllers (RC) provide for the exchange of routing
information (primitives) for the RA. The RC is protocol
independent and MAY be realized by multiple, different protocol
controllers within a RA. The routing information exchanged between
RCs SHALL be subject to policy constraints imposed at reference
points (External- and Internal-NNI)
- A multi-level RA hierarchy based on containment, only the RCs of
the parent RA communicate. RCs of child RAs never communicate with
the ASON routing requirements MUST RCs of other child RAs. There SHOULD not be
backward compatible with any dependencies
on the considered different routing protocol(s).

Backward compatibility means protocols used within a child RA and that at any level
of the its parent. The routing
hierarchy, nodes, some of which support information exchanged within the requirements described
in this document, and some of which do not, MUST still parent
RA SHALL be capable to
operate as mandated by independent of both the OSPF, IS-IS, and/or IDR IETF WG routing protocol operating
within a child RA, and their
corresponding GMPLS extensions (as mandated by any control distribution choice(s), e.g.
centralized, fully distributed.
- For a RA, the CCAMP IETF WG).

Additionally, nodes (that do not support these requirements and) are
made part set of a multi-level RCs is referred to as an ASON routing hierarchy from their containing
RA(s), must be capable of:
- rejecting (or ignoring) any incoming
(control) domain. The routing information that
would exchanged between
routing domains (inter-RA, i.e. inter-domain) SHALL be addressed to them in a way that is not detrimental to independent
of both the
network as a whole
- communicating (at a given level) with any other node located
at intra-domain routing protocol(s), and the intra-domain
control distribution choice(s), e.g. centralized, fully
distributed. RCs bounded to different RA levels MAY be co-located
within the same level and that implements these requirements
This assumes that such nodes do not communicate directly either with
lower physical element or upper level nodes.

Note: backward compatibility with physically distributed.
- The routing protocols is a protocol
requirement defined in adjacency topology (i.e. the IETF context. associated PC

W.Alanqar et al. - Expires July October 2004 10

6. Security Considerations

ASON routing protocol MUST deliver 11
connectivity topology) and the operational security
objectives where required.

7. Conclusions

This section captures transport network topology SHALL
NOT be assumed to be congruent
- The routing topology SHALL support multiple links between nodes
and RAs

In summary, the following functionality is expected from GMPLS
routing to instantiate the identified ASON hierarchical routing requirements architecture
realization (see [G.7715] and [G.7715.1]):
- RAs SHALL be uniquely identifiable within a carrier's network,
each having a unique RA ID within the missing capabilities from carrier's network.
- Within a RA (one level), the GMPLS routing protocols (e.g.
OSPF, IS-IS).

The GMPLS routing protocol is required to SHALL support multiple
hierarchical levels
dissemination of RAs and hierarchical routing information
dissemination including (including
summarized routing information. However, information for other levels) in support of an
architecture of multiple hierarchical levels of RAs; the number of
hierarchical RA levels to be supported is by a routing protocol is
implementation specific. This implies
- The routing protocol SHALL support routing information based on a
common set of information elements as defined in [G.7715] and
[G.7715.1], divided between attributes pertaining to links and
abstract nodes (each representing either a sub-network or simply a
node). [G.7715] recognizes that the GMPLS manner in which the routing
information is represented and exchanged will vary with the
routing protocol must used.
- The routing protocol SHALL converge such that the distributed RDBs
become synchronized after a period of time.

To support hierarchical routing information dissemination within an
RA, the 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 bound to 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 self-
consistent
- a mechanism to prevent re-introduction of information propagated
into the Level N RA RA's RC back to the external adjacent level RA RA's RC 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
relationships of RAs. These GMPLS RAs, the routing
capabilities are considered protocol SHALL support evolution
in terms of lower priority as they are
implementation specific and their method number of support should be
evaluated on per-protocol basis e.g. OSPF vs IS-IS. In addition, hierarchical levels of RAs. Example: support
of non-disruptive operations such as adding and removing RAs at the
top/bottom of the hierarchy, adding or removing a hierarchical level
of RAs in or from the middle of the routing
hierarchy are considered hierarchy, as the lowest priority requirements. Note
also that the well as
aggregation and segmentation of RAs. The number of hierarchical
levels to be supported is
implementation routing protocol 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 October 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 12
Reachability 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 (see Section 4.5.3) 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 set of externally endpoints
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) by a node may be advertised either as a set of UNI
Transport Resource addresses/ 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 prefixes, or 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 set of
dedicated TE
associated SNPP link attribute(s) to describe the cross/inter-layer
relationships. All other TE IDs/SNPP link attributes ID prefixes, assigned and characteristics are
currently covered. The need for a "TE metric" per component link
needs to be further assessed,
selected consistently in their applicability scope. The formats of
the sense that it can be currently
implemented. Further consideration is here needed regarding impacts
on TE link bundling capabilities and the increase control plane identifiers in a protocol realization are
implementation specific. Use of a routing protocol within a RA
should not restrict the choice of routing
advertisement overhead with potentially duplicated information.

Note: protocols for use in other
RAs (child or parent).

As ASON does not restrict the control plane architecture choices choice
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 A collection of the LSR requires a 1-to-1 relationship between the
transport plane entity links and the control plane entity (Router). They
invite CCAMP input on GMPLS capabilities nodes such as a
sub-network or RA MUST be able to represent itself 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 wider
network as a link advertisement.

The inheritance property of link attributes used single logical entity with only its external links
visible to optimize the
component/TE link configuration process is built in within GMPLS.

W.Alanqar et al. - Expires July 2004 12

8. topology database.

7. Acknowledgements

The authors would like to thank Kireeti Kompella for having
initiated the proposal of an ASON Routing Requirement Design Team.

8. Intellectual Property Considerations

The IETF takes no position regarding the validity or scope of any
intellectual property
Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology
described in this document or the extent to which any license
under such rights might or might not be available; neither nor does it
represent that it has made any independent effort to identify any
such rights. Information on the
IETF's procedures with respect to rights
in standards-track and
standards-related documentation RFC documents can be found in BCP-11. BCP 78 and BCP 79.

Copies of
claims of rights IPR disclosures made available for publication to the IETF Secretariat and any
assurances 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 proprietary rights by implementors implementers or users of this
specification can be obtained from the IETF Secretariat. on-line IPR repository
at http://www.ietf.org/ipr.

The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other
proprietary rights which that may cover technology that may be required
to practice implement this standard. Please address the information to the
IETF Executive
Director.

10. at ietf-ipr@ietf.org.

8.1 IPR Disclosure Acknowledgement

By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance
with RFC 3668.

W.Alanqar et al. - Expires October 2004 13

9. References

10.1

9.1 Normative References

[RFC 2026]

[RFC2026] S.Bradner, "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996.

[RFC 2119]

[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
Requirements for the Automatically Switched Optical
Network (ASON)," June 2002.

[G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing
Architecture and Requirements for Link State
Protocols," November 2003.

[G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003).

[HIER] K.Kompella and Y.Rekhter, "LSP Hierarchy with
Generalized MPLS TE," Internet draft (work in
progress), draft-ietf-mpls-lsp-hierarchy, Sept'02.

W.Alanqar et al. - Expires July 2004 13

11. September 02.

10. Author's Addresses

Wesam Alanqar (Sprint)
EMail: wesam.alanqar@mail.sprint.com

Deborah Brungard (AT&T)
Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA
Phone: +1 732 4201573
EMail: dbrungard@att.com

David Meyer (Cisco Systems)
EMail: dmm@1-4-5.net

Lyndon Ong (Ciena Corporation)
5965 Silver Creek Valley Rd,
San Jose, CA 95128, USA
Phone: +1 408 8347894
EMail: lyong@ciena.com

Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be

W.Alanqar et al. - Expires October 2004 14
Jonathan Sadler
1415 W. Diehl Rd
Naperville, IL 60563
EMail: jonathan.sadler@tellabs.com

Stephen Shew (Nortel Networks)
PO Box 3511 Station C
Ottawa, Ontario, CANADA K1Y 4H7
Phone: +1 613 7632462
EMail: sdshew@nortelnetworks.com

W.Alanqar et al. - Expires July October 2004 14 15

Appendix 1 - 1: ASON Terminology

This document makes use of the following terms: following terms:

Administrative domain: (Recommendation G.805 For the purposes of
[G7715.1] an administrative domain represents the extent of
resources which belong to a single player such as a network
operator, a service provider, or an end-user. Administrative domain: See Recommendation G.805. domains
of different players do not overlap amongst themselves.

Control plane: performs the call control and connection control
functions. Through signaling, the control plane sets up and releases
connections, and may restore a connection in case of a failure.

(Control) Domain: represents a collection of (control) entities that
are grouped for a particular purpose. G.8080 applies this G.805
recommendation concept (that defines two particular forms, the
administrative domain and the management domain) to the The control plane in the form is
subdivided into domains matching administrative domains. Within an
administrative domain, further subdivisions of a the control domain. The entities that plane are grouped
in a
recursively applied. A routing control domain are components is an abstract entity
that hides the details of the control plane. RC distribution.

External NNI (E-NNI): interfaces are located between protocol
controllers between control domains.

Internal NNI (I-NNI): interfaces are located between protocol
controllers within control domains.

Link: See [See Recommendation G.805. G.805] a "topological component" which
describes a fixed relationship between a "subnetwork" or "access
group" and another "subnetwork" or "access group". Links are not
limited to being provided by a single server trail.

Management plane: performs management functions for the Transport
Plane, the control plane and the system as a whole. It also provides
coordination between all the planes. The following management
functional areas are performed in the management plane: performance,
fault, configuration, accounting and security management

Management domain: See [See Recommendation G.805. G.805] A management domain
defines a collection of managed objects which are grouped to meet
organizational requirements according to geography, technology,
policy or other structure, and for a number of functional areas such
as configuration, security, (FCAPS), for the purpose of providing
control in a consistent manner. Management domains can be disjoint,
contained or overlapping. As such the resources within an
administrative domain can be distributed into several possible
overlapping management domains. The same resource can therefore
belong to several management domains simultaneously, but a
management domain shall not cross the border of an administrative
domain.

W.Alanqar et al. - Expires October 2004 16
SNP: The SNP is a control plane abstraction that represents an
actual or potential transport plane resource. SNPs (in different
subnetwork partitions) may represent the same transport resource. A
one-to-one correspondence should not be assumed.

Transport plane: provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also
provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport
Network defined in G.805.

User Network Interface (UNI): interfaces are located between
protocol controllers between a user and a control domain. Note:
there is no routing function associated with a UNI reference point.

W.Alanqar et al. - Expires July October 2004 15 17

Appendix 2 - 2: ASON Routing Terminology

This document makes use of the following terms:

Routing Area (RA): a RA represents a partition of the data plane and
its identifier is used within the control plane as the
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
topology, reachability, and other routing information that is
updated as part of the routing information exchange and may
additionally contain information that is configured. The RDB may
contain routing information for more than one Routing Area (RA).

Routing Components: ASON routing architecture functions. These
functions can be classified as protocol independent (Link Resource
Manager or LRM, Routing Controller or RC) and protocol specific
(Protocol Controller or PC).

Routing Controller (RC): handles (abstract) information needed for
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
is protocol independent.

Note: Since the RDB may contain routing information pertaining to
multiple RAs (and hence possibly to multiple layer networks), the RCs
accessing the RDB may share the routing information.

Link Resource Manager (LRM): supplies all the relevant component and
TE link information to the RC. It informs the RC about any state
changes of the link resources it controls.

Protocol Controller (PC): handles protocol specific message
exchanges according to the reference point over which the
information is exchanged (e.g. E-NNI, I-NNI), and internal exchanges
with the RC. The PC function is protocol dependent.

W.Alanqar et al. - Expires July October 2004 16 18

Full Copyright Statement

"Copyright

Copyright (C) The Internet Society (2003). All Rights Reserved. (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78 and
except as set forth therein, the authors retain all their rights.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

W.Alanqar et al. - Expires July October 2004 17 19