draft-ietf-ccamp-gmpls-architecture-01.txt   draft-ietf-ccamp-gmpls-architecture-02.txt 
Network Working Group Eric Mannie (Ebone) - Editor Network Working Group Eric Mannie (Ebone) - Editor
Internet Draft Internet Draft
Expiration date: May 2002 Peter Ashwood-Smith (Nortel) Expiration date: Sept. 2002 Peter Ashwood-Smith (Nortel)
Daniel Awduche (Movaz) Daniel Awduche (Movaz)
Ayan Banerjee (Calient) Ayan Banerjee (Calient)
Debashis Basak (Accelight) Debashis Basak (Accelight)
Lou Berger (Movaz) Lou Berger (Movaz)
Greg Bernstein (Ciena) Greg Bernstein (Ciena)
Sudheer Dharanikota (Nayna) Sudheer Dharanikota (Nayna)
John Drake (Calient) John Drake (Calient)
Yanhe Fan (Axiowave) Yanhe Fan (Axiowave)
Don Fedyk (Nortel) Don Fedyk (Nortel)
Gert Grammel (Alcatel) Gert Grammel (Alcatel)
skipping to change at line 34 skipping to change at line 34
Bala Rajagopalan (Tellium) Bala Rajagopalan (Tellium)
Yakov Rekhter (Juniper) Yakov Rekhter (Juniper)
Debanjan Saha (Tellium) Debanjan Saha (Tellium)
Hal Sandick (Nortel) Hal Sandick (Nortel)
Vishal Sharma (Metanoia) Vishal Sharma (Metanoia)
George Swallow (Cisco) George Swallow (Cisco)
Z. Bo Tang (Tellium) Z. Bo Tang (Tellium)
Jennifer Yates (AT&T) Jennifer Yates (AT&T)
George R. Young (Edgeflow) George R. Young (Edgeflow)
John Yu (Zaffire) John Yu (Zaffire)
Alex Zinin (Cisco) Alex Zinin (Nexsi Systems)
November 2001 March 2002
Generalized Multi-Protocol Label Switching (GMPLS) Architecture Generalized Multi-Protocol Label Switching (GMPLS) Architecture
draft-ietf-ccamp-gmpls-architecture-01.txt draft-ietf-ccamp-gmpls-architecture-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 RFC2026 [1]. all provisions of Section 10 of RFC2026 [1].
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
E. Mannie et. al. 1 E. Mannie et. al. 1
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001 draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet- Drafts as at any time. It is inappropriate to use Internet- Drafts as
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
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http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Table of Contents Table of Contents
Status of this Memo................................................1 Status of this Memo................................................1
Table of Contents..................................................2 Table of Contents..................................................2
1. Abstract........................................................4 1. Abstract........................................................4
1.1. List of open issues...........................................4
2. Conventions used in this document...............................4 2. Conventions used in this document...............................4
3. Introduction....................................................4 3. Introduction....................................................4
3.1. Acronyms & abbreviations......................................5 3.1. Acronyms & abbreviations......................................5
3.2. Multiple Types of Switching and Forwarding Hierarchies........5 3.2. Multiple Types of Switching and Forwarding Hierarchies........5
3.3. Extension of the MPLS Control Plane...........................7 3.3. Extension of the MPLS Control Plane...........................7
3.4. GMPLS Key Extensions to MPLS-TE..............................10 3.4. GMPLS Key Extensions to MPLS-TE..............................10
4. Routing and addressing model...................................11 4. Routing and addressing model...................................11
4.1. Addressing of PSC and non-PSC layers.........................12 4.1. Addressing of PSC and non-PSC layers.........................12
4.2. GMPLS scalability enhancements...............................12 4.2. GMPLS scalability enhancements...............................12
4.3. TE Extensions to IP routing protocols........................13 4.3. TE Extensions to IP routing protocols........................13
5. Unnumbered links...............................................14 5. Unnumbered links...............................................14
5.1. Unnumbered Forwarding Adjacencies............................15 5.1. Unnumbered Forwarding Adjacencies............................15
6. Link bundling..................................................15 6. Link bundling..................................................15
6.1. Restrictions on bundling.....................................15 6.1. Restrictions on bundling.....................................16
6.2. Routing considerations for bundling..........................16 6.2. Routing considerations for bundling..........................16
6.3. Signaling considerations.....................................16 6.3. Signaling considerations.....................................17
6.3.1. Mechanism 1: Implicit Indication...........................17 6.3.1. Mechanism 1: Implicit Indication...........................17
6.3.2. Mechanism 2: Explicit Indication by Numbered Interface ID..17 6.3.2. Mechanism 2: Explicit Indication by Numbered Interface ID..17
6.3.3. Mechanism 3: Explicit Indication by Unnumbered Interface ID17 6.3.3. Mechanism 3: Explicit Indication by Unnumbered Interface ID17
6.4. Unnumbered Bundled Link......................................18 6.4. Unnumbered Bundled Link......................................18
6.5. Forming TE links.............................................18 6.5. Forming bundled links........................................18
7. Relationship with the UNI......................................18 7. Relationship with the UNI......................................19
7.1. Relationship with the OIF UNI................................19 7.1. Relationship with the OIF UNI................................19
7.2. Reachability across the UNI..................................19 7.2. Reachability across the UNI..................................19
8. Link Management................................................20 8. Link Management................................................20
8.1. Control channel and control channel management...............21 8.1. Control channel and control channel management...............21
8.2. Link property correlation....................................22 8.2. Link property correlation....................................22
8.3. Link connectivity verification...............................22 8.3. Link connectivity verification...............................22
8.4. Fault management.............................................23 8.4. Fault management.............................................23
9. Generalized Signaling..........................................24 8.5 LMP for DWDM Optical Line Systems (OLSs)......................23
9.1. Overview: How to Request an LSP..............................25 9. Generalized Signaling..........................................25
9.2. Generalized Label Request....................................26 9.1. Overview: How to Request an LSP..............................26
9.3. SONET/SDH Traffic Parameters.................................27 9.2. Generalized Label Request....................................27
9.4. G.709 Traffic Parameters.....................................28 9.3. SONET/SDH Traffic Parameters.................................28
9.5. Bandwidth Encoding...........................................29 9.4. G.709 Traffic Parameters.....................................29
9.6. Generalized Label............................................29 9.5. Bandwidth Encoding...........................................30
9.7. Waveband Switching...........................................30 9.6. Generalized Label............................................30
9.7. Waveband Switching...........................................31
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9.8. Label Suggestion by the Upstream.............................30 9.8. Label Suggestion by the Upstream.............................31
9.9. Label Restriction by the Upstream............................30 9.9. Label Restriction by the Upstream............................32
9.10. Bi-directional LSP..........................................31 9.10. Bi-directional LSP..........................................32
9.11. Bi-directional LSP Contention Resolution....................32 9.11. Bi-directional LSP Contention Resolution....................33
9.12. Rapid Notification of Failure...............................32 9.12. Rapid Notification of Failure...............................33
9.13. Link Protection.............................................33 9.13. Link Protection.............................................34
9.14. Explicit Routing and Explicit Label Control.................34 9.14. Explicit Routing and Explicit Label Control.................35
9.15. Route recording.............................................35 9.15. Route recording.............................................36
9.16. LSP modification and LSP re-routing.........................35 9.16. LSP modification and LSP re-routing.........................36
9.17. LSP administrative status handling..........................35 9.17. LSP administrative status handling..........................37
9.18. Control channel separation..................................36 9.18. Control channel separation..................................37
10. Forwarding Adjacencies (FA)...................................37 10. Forwarding Adjacencies (FA)...................................38
10.1. Routing and Forwarding Adjacencies..........................38 10.1. Routing and Forwarding Adjacencies..........................39
10.2. Signaling aspects...........................................39 10.2. Signaling aspects...........................................40
10.3. Cascading of Forwarding Adjacencies.........................39 10.3. Cascading of Forwarding Adjacencies.........................40
11. Control Plane Fault Handling..................................39 11. Routing and Signaling Adjacencies.............................41
12. LSP Protection and Restoration................................40 12. Control Plane Fault Handling..................................42
12.1. Protection escalation across domains and layers.............41 13. LSP Protection and Restoration................................43
12.2. Mapping of Services to P&R Resources........................42 13.1. Protection escalation across domains and layers.............43
12.3. Classification of P&R mechanism characteristics.............42 13.2. Mapping of Services to P&R Resources........................44
12.4. Different Stages in P&R.....................................43 13.3. Classification of P&R mechanism characteristics.............45
12.5. Recovery Strategies.........................................43 13.4. Different Stages in P&R.....................................45
12.6. Recovery mechanisms: Protection schemes.....................44 13.5. Recovery Strategies.........................................46
12.7. Recovery mechanisms: Restoration schemes....................44 13.6. Recovery mechanisms: Protection schemes.....................46
12.8. Schema selection criteria...................................45 13.7. Recovery mechanisms: Restoration schemes....................47
13. Network Management............................................46 13.8. Schema selection criteria...................................48
13.1. Network Management Systems (NMS)............................47 14. Network Management............................................49
13.2. Management Information Base (MIB)...........................47 14.1. Network Management Systems (NMS)............................49
13.3. Tools.......................................................48 14.2. Management Information Base (MIB)...........................50
13.4. Fault Correlation Between Multiple Layers...................48 14.3. Tools.......................................................50
14. Security considerations.......................................49 14.4. Fault Correlation Between Multiple Layers...................50
15. Acknowledgements..............................................49 15. Security considerations.......................................51
16. References....................................................50 16. Acknowledgements..............................................52
17. Author's Addresses............................................53 17. References....................................................53
Full Copyright Statement..........................................55 18. Author's Addresses............................................55
Full Copyright Statement..........................................58
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1. Abstract 1. Abstract
Future data and transmission networks will consist of elements such Future data and transmission networks will consist of elements such
as routers, switches, DWDM systems, Add-Drop Multiplexors (ADMs), as routers, switches, DWDM systems, Add-Drop Multiplexors (ADMs),
photonic cross-connects (PXCs), optical cross-connects (OXCs), etc photonic cross-connects (PXCs), optical cross-connects (OXCs), etc
that will use Generalized MPLS (GMPLS) to dynamically provision that will use Generalized MPLS (GMPLS) to dynamically provision
resources and to provide network survivability using protection and resources and to provide network survivability using protection and
restoration techniques. restoration techniques.
This document describes the architecture of GMPLS. GMPLS extends This document describes the architecture of GMPLS. GMPLS extends
MPLS to encompass time-division (e.g. SDH/SONET, PDH, G.709), MPLS to encompass time-division (e.g. SDH/SONET, PDH, G.709),
wavelength (lambdas), and spatial switching (e.g. incoming port or wavelength (lambdas), and spatial switching (e.g. incoming port or
fiber to outgoing port or fiber). The main focus of GMPLS is on the fiber to outgoing port or fiber). The main focus of GMPLS is on the
control plane of these various layers since each of them can use control plane of these various layers since each of them can use
physically diverse data or forwarding planes. The intention is to physically diverse data or forwarding planes. The intention is to
cover both the signaling and the routing part of that control plane. cover both the signaling and the routing part of that control plane.
1.1. List of open issues
This section lists several open issues on which the various people
are currently working.
- Inter-domain operations (e.g. routing with BGP-4).
- Protection and restoration for GMPLS.
- VPN support.
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 [2]. this document are to be interpreted as described in RFC-2119 [2].
3. Introduction 3. Introduction
The architecture presented in this document covers the main building The architecture presented in this document covers the main building
blocks needed to build a consistent control plane for multiple blocks needed to build a consistent control plane for multiple
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work together. Different models can be applied: e.g. overlay, work together. Different models can be applied: e.g. overlay,
augmented or integrated. Moreover, each pair of contiguous layer may augmented or integrated. Moreover, each pair of contiguous layer may
work jointly in a different way, resulting in a number of possible work jointly in a different way, resulting in a number of possible
combinations, at the discretion of manufacturers and operators. combinations, at the discretion of manufacturers and operators.
This architecture clearly separates the control plane and the This architecture clearly separates the control plane and the
forwarding plane. In addition, it also clearly separates the control forwarding plane. In addition, it also clearly separates the control
plane in two parts, the signaling plane containing the signaling plane in two parts, the signaling plane containing the signaling
protocols and the routing plane containing the routing protocols. protocols and the routing plane containing the routing protocols.
This document is a generalization of the MPLS architecture [MPLS- This document is a generalization of the MPLS architecture
ARCH], and in some cases may differ slightly from that architecture [RFC3031], and in some cases may differ slightly from that
since non packet-based forwarding planes are now considered. It is architecture since non packet-based forwarding planes are now
not the intention of this document to describe concepts already considered. It is not the intention of this document to describe
described in the current MPLS architecture. The goal is to describe concepts already described in the current MPLS architecture. The
specific concepts of Generalized MPLS (GMPLS). goal is to describe specific concepts of Generalized MPLS (GMPLS).
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However, some of the concepts explained hereafter are not part of However, some of the concepts explained hereafter are not part of
the current MPLS architecture and are applicable to both MPLS and the current MPLS architecture and are applicable to both MPLS and
GMPLS (i.e. link bundling, unnumbered links, and LSP hierarchy). GMPLS (i.e. link bundling, unnumbered links, and LSP hierarchy).
Since these concepts were introduced together with GMPLS and since Since these concepts were introduced together with GMPLS and since
they are of paramount importance for an operational GMPLS network, they are of paramount importance for an operational GMPLS network,
they will be discussed here. they will be discussed here.
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The organization of the remainder of this draft is as follows. We The organization of the remainder of this draft is as follows. We
begin with an introduction of GMPLS. We then present the specific begin with an introduction of GMPLS. We then present the specific
GMPLS building blocks and explain how they can be combined together GMPLS building blocks and explain how they can be combined together
to build an operational GMPLS networks. Specific details of the to build an operational GMPLS networks. Specific details of the
separate building blocks can be found in the corresponding separate building blocks can be found in the corresponding
documents. documents.
3.1. Acronyms & abbreviations 3.1. Acronyms & abbreviations
ABR Area Border Router ABR Area Border Router
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Generalized MPLS (GMPLS) differs from traditional MPLS in that it Generalized MPLS (GMPLS) differs from traditional MPLS in that it
supports multiple types of switching, i.e. the addition of support supports multiple types of switching, i.e. the addition of support
for TDM, lambda, and fiber (port) switching. The support for the for TDM, lambda, and fiber (port) switching. The support for the
additional types of switching has driven GMPLS to extend certain additional types of switching has driven GMPLS to extend certain
base functions of traditional MPLS and, in some cases, to add base functions of traditional MPLS and, in some cases, to add
functionality. These changes and additions impact basic LSP functionality. These changes and additions impact basic LSP
properties, how labels are requested and communicated, the properties, how labels are requested and communicated, the
unidirectional nature of LSPs, how errors are propagated, and unidirectional nature of LSPs, how errors are propagated, and
information provided for synchronizing the ingress and egress LSRs. information provided for synchronizing the ingress and egress LSRs.
E. Mannie et. al. Internet-Draft May 2002 5 The MPLS architecture [RFC3031] was defined to support the
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
The MPLS architecture [MPLS-ARCH] was defined to support the
forwarding of data based on a label. In this architecture, Label forwarding of data based on a label. In this architecture, Label
Switching Routers (LSRs) were assumed to have a forwarding plane Switching Routers (LSRs) were assumed to have a forwarding plane
that is capable of (a) recognizing either packet or cell boundaries, that is capable of (a) recognizing either packet or cell boundaries,
and (b) being able to process either packet headers (for LSRs and (b) being able to process either packet headers (for LSRs
capable of recognizing packet boundaries) or cell headers (for LSRs capable of recognizing packet boundaries) or cell headers (for LSRs
capable of recognizing cell boundaries). capable of recognizing cell boundaries).
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The original MPLS architecture is here being extended to include The original MPLS architecture is here being extended to include
LSRs whose forwarding plane recognizes neither packet, nor cell LSRs whose forwarding plane recognizes neither packet, nor cell
boundaries, and therefore, can't forward data based on the boundaries, and therefore, can't forward data based on the
information carried in either packet or cell headers. Specifically, information carried in either packet or cell headers. Specifically,
such LSRs include devices where the forwarding decision is based on such LSRs include devices where the forwarding decision is based on
time slots, wavelengths, or physical ports. So, the new set of LSRs, time slots, wavelengths, or physical ports. So, the new set of LSRs,
or more precisely interfaces on these LSRs, can be subdivided into or more precisely interfaces on these LSRs, can be subdivided into
the following classes: the following classes:
1. Packet Switch Capable (PSC) interfaces: 1. Packet Switch Capable (PSC) interfaces:
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4. Lambda Switch Capable (LSC) interfaces: 4. Lambda Switch Capable (LSC) interfaces:
Interfaces that forward data based on the wavelength on which the Interfaces that forward data based on the wavelength on which the
data is received. An example of such an interface is that of a data is received. An example of such an interface is that of a
Photonic Cross-Connect (PXC) or Optical Cross-Connect (OXC) that can Photonic Cross-Connect (PXC) or Optical Cross-Connect (OXC) that can
operate at the level of an individual wavelength. Additional operate at the level of an individual wavelength. Additional
examples include PXC interfaces that can operate at the level of a examples include PXC interfaces that can operate at the level of a
group of wavelengths, i.e. a waveband and G.709 interfaces providing group of wavelengths, i.e. a waveband and G.709 interfaces providing
optical capabilities. optical capabilities.
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5. Fiber-Switch Capable (FSC) interfaces: 5. Fiber-Switch Capable (FSC) interfaces:
Interfaces that forward data based on a position of the data in the Interfaces that forward data based on a position of the data in the
real world physical spaces. An example of such an interface is that real world physical spaces. An example of such an interface is that
of a PXC or OXC that can operate at the level of a single or of a PXC or OXC that can operate at the level of a single or
multiple fibers. multiple fibers.
A circuit can be established only between, or through, interfaces of A circuit can be established only between, or through, interfaces of
the same type. Depending on the particular technology being used for the same type. Depending on the particular technology being used for
each interface, different circuit names can be used, e.g. SDH each interface, different circuit names can be used, e.g. SDH
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circuit, optical trail, light-path, etc. In the context of GMPLS, circuit, optical trail, light-path, etc. In the context of GMPLS,
all these circuits are referenced by a common name: Label Switched all these circuits are referenced by a common name: Label Switched
Path (LSP). Path (LSP).
The concept of nested LSP (LSP within LSP), already available in the The concept of nested LSP (LSP within LSP), already available in the
traditional MPLS, facilitates building a forwarding hierarchy, i.e. traditional MPLS, facilitates building a forwarding hierarchy, i.e.
a hierarchy of LSPs. This hierarchy of LSPs can occur on the same a hierarchy of LSPs. This hierarchy of LSPs can occur on the same
interface, or between different interfaces. interface, or between different interfaces.
For example, a hierarchy can be built if an interface is capable of For example, a hierarchy can be built if an interface is capable of
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Note that the GMPLS control plane supports an overlay model, an Note that the GMPLS control plane supports an overlay model, an
augmented model, and a peer (integrated) model. In the near term, augmented model, and a peer (integrated) model. In the near term,
GMPLS is very suitable for controlling each layer independently. GMPLS is very suitable for controlling each layer independently.
This elegant approach will facilitate the future deployment of other This elegant approach will facilitate the future deployment of other
models. models.
The GMPLS control plane is made of several building blocks are The GMPLS control plane is made of several building blocks are
described in more detail in the following sections. These building described in more detail in the following sections. These building
blocks are based on well-known signaling and routing protocols that blocks are based on well-known signaling and routing protocols that
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have been extended and/or modified to support GMPLS. They use IPv4 have been extended and/or modified to support GMPLS. They use IPv4
and/or IPv6 addresses. Only one new specialized protocol is required and/or IPv6 addresses. Only one new specialized protocol is required
to support the operations of GMPLS, a signaling protocol for link to support the operations of GMPLS, a signaling protocol for link
management [LMP]. management [LMP].
GMPLS is indeed based on the Traffic Engineering (TE) extensions to GMPLS is indeed based on the Traffic Engineering (TE) extensions to
MPLS, a.k.a. MPLS-TE. This because most of the technologies that can MPLS, a.k.a. MPLS-TE. This because most of the technologies that can
be used below the PSC level require some traffic engineering. The be used below the PSC level require some traffic engineering. The
placement of LSPs at these levels needs in general to take several placement of LSPs at these levels needs in general to take several
constraints into consideration (such as framing, bandwidth, constraints into consideration (such as framing, bandwidth,
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protection capability, etc) and to bypass the legacy Shortest-Path protection capability, etc) and to bypass the legacy Shortest-Path
First (SPF) algorithm. Note, however, that this is not mandatory and First (SPF) algorithm. Note, however, that this is not mandatory and
that in some cases SPF routing can be applied. that in some cases SPF routing can be applied.
In order to facilitate constrained-based SPF routing of LSPs, the In order to facilitate constrained-based SPF routing of LSPs, the
nodes performing LSP establishment need more information about the nodes performing LSP establishment need more information about the
links in the network than standard intra-domain routing protocols links in the network than standard intra-domain routing protocols
provide. These TE attributes are distributed using the transport provide. These TE attributes are distributed using the transport
mechanisms already available in IGPs (e.g. flooding) and taken into mechanisms already available in IGPs (e.g. flooding) and taken into
consideration by the LSP routing algorithm. Optimization of the LSP consideration by the LSP routing algorithm. Optimization of the LSP
routes may also require some external simulations using heuristics routes may also require some external simulations using heuristics
that serve as input for the actual path calculation and LSP that serve as input for the actual path calculation and LSP
establishment process. establishment process.
By definition, a TE link is a representation in the ISIS/OSPF Link
State advertisements and in the link state database of certain
physical resources, and their properties, between two GMPLS nodes.
TE Links are used by the GMPLS control plane (routing and signaling)
for establishing LSPs.
Extensions to traditional routing protocols and algorithms are Extensions to traditional routing protocols and algorithms are
needed to uniformly encode and carry TE link information, and needed to uniformly encode and carry TE link information, and
explicit routes (e.g. source routes) are required in the signaling. explicit routes (e.g. source routes) are required in the signaling.
In addition, the signaling must now be capable of transporting the In addition, the signaling must now be capable of transporting the
required circuit (LSP) parameters such as the bandwidth, the type of required circuit (LSP) parameters such as the bandwidth, the type of
signal, the desired protection and/or restoration, the position in a signal, the desired protection and/or restoration, the position in a
particular multiplex, etc. Most of these extensions have already particular multiplex, etc. Most of these extensions have already
been defined for PSC and L2SC traffic engineering with MPLS. GMPLS been defined for PSC and L2SC traffic engineering with MPLS. GMPLS
primarily defines additional extensions for TDM, LSC, and FSC primarily defines additional extensions for TDM, LSC, and FSC
traffic engineering. A very few elements are technology specific. traffic engineering. A very few elements are technology specific.
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downstream-on-demand label allocation and distribution, with an downstream-on-demand label allocation and distribution, with an
ingress initiated ordered control. Liberal label retention is ingress initiated ordered control. Liberal label retention is
normally used, but conservative label retention mode could also be normally used, but conservative label retention mode could also be
used. Furthermore, there is no restriction on the label allocation used. Furthermore, there is no restriction on the label allocation
strategy, it can be request/signaling driven (obvious for circuit strategy, it can be request/signaling driven (obvious for circuit
switching technologies), traffic/data driven, or even topology switching technologies), traffic/data driven, or even topology
driven. There is also no restriction on the route selection; driven. There is also no restriction on the route selection;
explicit routing is normally used (strict or loose) but hop-by-hop explicit routing is normally used (strict or loose) but hop-by-hop
routing could be used as well. routing could be used as well.
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GMPLS also extends two traditional intra-domain link-state routing GMPLS also extends two traditional intra-domain link-state routing
protocols already extended for TE purposes, i.e. OSPF-TE and IS-IS- protocols already extended for TE purposes, i.e. OSPF-TE and IS-IS-
TE. However, if explicit (source) routing is used, the routing TE. However, if explicit (source) routing is used, the routing
algorithms used by these protocols no longer need to be algorithms used by these protocols no longer need to be
standardized. Extensions for inter-domain routing (e.g. BGP) are for standardized. Extensions for inter-domain routing (e.g. BGP) are for
further study. further study.
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The use of technologies like DWDM (Dense Wavelength Division The use of technologies like DWDM (Dense Wavelength Division
Multiplexing) implies that we can now have a very large number of Multiplexing) implies that we can now have a very large number of
parallel links between two directly adjacent nodes (hundreds of parallel links between two directly adjacent nodes (hundreds of
wavelengths, or even thousands of wavelengths if multiple fibers are wavelengths, or even thousands of wavelengths if multiple fibers are
used). Such a large number of links was not originally considered used). Such a large number of links was not originally considered
for an IP or MPLS control plane, although it could be done. Some for an IP or MPLS control plane, although it could be done. Some
slight adaptations of that control plane are thus required if we slight adaptations of that control plane are thus required if we
want to better reuse it in the GMPLS context. want to better reuse it in the GMPLS context.
For instance, the traditional IP routing model assumes the For instance, the traditional IP routing model assumes the
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The MPLS signaling and routing protocols require at least one bi- The MPLS signaling and routing protocols require at least one bi-
directional control channel to communicate even if two adjacent directional control channel to communicate even if two adjacent
nodes are connected by unidirectional links. Several control nodes are connected by unidirectional links. Several control
channels can be used. LMP can be used to establish, maintain and channels can be used. LMP can be used to establish, maintain and
manage these control channels. manage these control channels.
GMPLS does not specify how these control channels must be GMPLS does not specify how these control channels must be
implemented, but GMPLS requires IP to transport the signaling and implemented, but GMPLS requires IP to transport the signaling and
routing protocols over them. Control channels can be either in-band routing protocols over them. Control channels can be either in-band
or out-of-band, and several solutions can be used to carry IP. Note or out-of-band, and several solutions can be used to carry IP. Note
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also that one type of LMP message (the Test message) is used in-band also that one type of LMP message (the Test message) is used in-band
in the data plane and may not be transported over IP, but this is a in the data plane and may not be transported over IP, but this is a
particular case, needed to verify connectivity in the data plane. particular case, needed to verify connectivity in the data plane.
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3.4. GMPLS Key Extensions to MPLS-TE 3.4. GMPLS Key Extensions to MPLS-TE
Some key extensions brought by GMPLS to MPLS-TE are highlighted in Some key extensions brought by GMPLS to MPLS-TE are highlighted in
the following. Some of them are key advantages of GMPLS to control the following. Some of them are key advantages of GMPLS to control
TDM, LSC and FSC layers. TDM, LSC and FSC layers.
- In MPLS-TE, links traversed by an LSP can include an intermix of - In MPLS-TE, links traversed by an LSP can include an intermix of
links with heterogeneous label encoding (e.g. links between routers, links with heterogeneous label encoding (e.g. links between routers,
links between routers and ATM-LSRs, and links between ATM-LSRs. links between routers and ATM-LSRs, and links between ATM-LSRs.
GMPLS extends this by including links where the label is encoded as GMPLS extends this by including links where the label is encoded as
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LSPs. LSPs.
- GMPLS supports the termination of an LSP on a specific egress - GMPLS supports the termination of an LSP on a specific egress
port, i.e. the port selection at the destination side. port, i.e. the port selection at the destination side.
- GMPLS with RSVP-TE supports an RSVP specific mechanism for rapid - GMPLS with RSVP-TE supports an RSVP specific mechanism for rapid
failure notification. failure notification.
Note also some other key differences between MPLS-TE and GMPLS: Note also some other key differences between MPLS-TE and GMPLS:
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- For TDM, LSC and FSC interfaces, bandwidth allocation for an LSP - For TDM, LSC and FSC interfaces, bandwidth allocation for an LSP
can be performed only in discrete units. can be performed only in discrete units.
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- It is expected to have (much) fewer labels on TDM, LSC or FSC - It is expected to have (much) fewer labels on TDM, LSC or FSC
links than on PSC or L2SC links, because the former are physical links than on PSC or L2SC links, because the former are physical
labels instead of logical labels. labels instead of logical labels.
4. Routing and addressing model 4. Routing and addressing model
GMPLS is based on the IP routing and addressing models. This assumes GMPLS is based on the IP routing and addressing models. This assumes
that IPv4 and/or IPv6 addresses are used to identify interfaces and that IPv4 and/or IPv6 addresses are used to identify interfaces and
that traditional (distributed) IP routing protocols are also reused. that traditional (distributed) IP routing protocols are also reused.
Indeed, the discovery of the topology and the resource state of all Indeed, the discovery of the topology and the resource state of all
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inter-domain routing protocol like BGP-4. There is obviously a huge inter-domain routing protocol like BGP-4. There is obviously a huge
value of re-using well-known policy routing facilities provided by value of re-using well-known policy routing facilities provided by
BGP in a non-PSC context. Extensions for BGP traffic engineering BGP in a non-PSC context. Extensions for BGP traffic engineering
(BGP-TE) in the context of non-PSC layers are left for further (BGP-TE) in the context of non-PSC layers are left for further
study. study.
Each AS can be subdivided in different routing domains, and each can Each AS can be subdivided in different routing domains, and each can
run a different intra-domain routing protocol. In turn, each run a different intra-domain routing protocol. In turn, each
routing-domain can be divided in areas. routing-domain can be divided in areas.
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A routing domain is made of GMPLS enabled nodes (i.e. a network A routing domain is made of GMPLS enabled nodes (i.e. a network
device including a GMPLS entity). These nodes can be either edge device including a GMPLS entity). These nodes can be either edge
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nodes (i.e. hosts, ingress LSRs or egress LSRs), or internal LSRs. nodes (i.e. hosts, ingress LSRs or egress LSRs), or internal LSRs.
An example of non-PSC host is an SDH/SONET Terminal Multiplexer An example of non-PSC host is an SDH/SONET Terminal Multiplexer
(TM). Another example is an SDH/SONET interface card within an IP (TM). Another example is an SDH/SONET interface card within an IP
router or ATM switch. router or ATM switch.
Note that traffic engineering in the intra-domain requires the use Note that traffic engineering in the intra-domain requires the use
of link-state routing protocols like OSPF or IS-IS. of link-state routing protocols like OSPF or IS-IS.
GMPLS defines extensions to these protocols. These extensions are GMPLS defines extensions to these protocols. These extensions are
needed to disseminate specific TDM, LSC and FSC static and dynamic needed to disseminate specific TDM, LSC and FSC static and dynamic
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several hundreds of wavelengths per fiber. several hundreds of wavelengths per fiber.
It becomes rather impractical to associate an IP address with each It becomes rather impractical to associate an IP address with each
end of each physical link, to represent each link as a separate end of each physical link, to represent each link as a separate
routing adjacency, and to advertise and to maintain link states for routing adjacency, and to advertise and to maintain link states for
each of these links. For that purpose, GMPLS enhances the MPLS each of these links. For that purpose, GMPLS enhances the MPLS
routing and addressing models to increase their scalability. routing and addressing models to increase their scalability.
Two optional mechanisms can be used to increase the scalability of Two optional mechanisms can be used to increase the scalability of
the addressing and the routing: unnumbered links and link bundling. the addressing and the routing: unnumbered links and link bundling.
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These two mechanisms can also be combined. They require extensions These two mechanisms can also be combined. They require extensions
to signaling (RSVP-TE and CR-LDP) and routing (OSPF-TE and IS-IS-TE) to signaling (RSVP-TE and CR-LDP) and routing (OSPF-TE and IS-IS-TE)
protocols. protocols.
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4.3. TE Extensions to IP routing protocols 4.3. TE Extensions to IP routing protocols
Traditionally, a TE link is advertised as an adjunct to a "regular" Traditionally, a TE link is advertised as an adjunct to a "regular"
OSPF or IS-IS link, i.e., an adjacency is brought up on the link, OSPF or IS-IS link, i.e., an adjacency is brought up on the link,
and when the link is up, both the regular IGP properties of the link and when the link is up, both the regular IGP properties of the link
(basically, the SPF metric) and the TE properties of the link are (basically, the SPF metric) and the TE properties of the link are
then advertised. then advertised.
However, GMPLS challenges this notion in three ways: However, GMPLS challenges this notion in three ways:
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TE properties associated with a link should also capture protection TE properties associated with a link should also capture protection
and restoration related characteristics. For instance, shared and restoration related characteristics. For instance, shared
protection can be elegantly combined with bundling. Protection and protection can be elegantly combined with bundling. Protection and
restoration are mainly generic mechanisms also applicable to MPLS. restoration are mainly generic mechanisms also applicable to MPLS.
It is expected that they will first be developed for MPLS and later It is expected that they will first be developed for MPLS and later
on generalized to GMPLS. on generalized to GMPLS.
A TE link between a pair of LSRs doesn't imply the existence of an A TE link between a pair of LSRs doesn't imply the existence of an
IGP adjacency between these LSRs. A TE link must also have some IGP adjacency between these LSRs. A TE link must also have some
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means by which the advertising LSR can know of its liveness (e.g. by means by which the advertising LSR can know of its liveness (e.g. by
using LMP hellos). When an LSR knows that a TE link is up, and can using LMP hellos). When an LSR knows that a TE link is up, and can
determine the TE link's TE properties, the LSR may then advertise determine the TE link's TE properties, the LSR may then advertise
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that link to its GMPLS enhanced OSPF or IS-IS neighbors using the TE that link to its GMPLS enhanced OSPF or IS-IS neighbors using the TE
objects/TLVs. We call the interfaces over which GMPLS enhanced OSPF objects/TLVs. We call the interfaces over which GMPLS enhanced OSPF
or ISIS adjacencies are established "control channels". or ISIS adjacencies are established "control channels".
5. Unnumbered links 5. Unnumbered links
Unnumbered links (or interfaces) are links (or interfaces) that do Unnumbered links (or interfaces) are links (or interfaces) that do
not have IP addresses. Using such links involves two capabilities: not have IP addresses. Using such links involves two capabilities:
the ability to specify unnumbered links in MPLS TE signaling, and the ability to specify unnumbered links in MPLS TE signaling, and
the ability to carry (TE) information about unnumbered links in IGP the ability to carry (TE) information about unnumbered links in IGP
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requires extensions to RSVP-TE and CR-LDP. The MPLS-TE signaling requires extensions to RSVP-TE and CR-LDP. The MPLS-TE signaling
doesn't provide support for unnumbered links, because it doesnÆt doesn't provide support for unnumbered links, because it doesnÆt
provide a way to indicate an unnumbered link in its Explicit Route provide a way to indicate an unnumbered link in its Explicit Route
Object/TLV and in its Record Route Object (there is no such TLV Object/TLV and in its Record Route Object (there is no such TLV
for CR-LDP). GMPLS defines simple extensions to indicate an for CR-LDP). GMPLS defines simple extensions to indicate an
unnumbered link in these two Objects/TLVs, using a new Unnumbered unnumbered link in these two Objects/TLVs, using a new Unnumbered
Interface ID sub-object/sub-TLV. Interface ID sub-object/sub-TLV.
Since unnumbered links are not identified by an IP address, then Since unnumbered links are not identified by an IP address, then
for the purpose of MPLS TE each end need some other identifier, for the purpose of MPLS TE each end need some other identifier,
local to the LSR to which the link belongs. Note that links are local to the LSR to which the link belongs. LSRs at the two end
directed, i.e., a link l is from some LSR A to some other LSR B. points of an unnumbered link exchange with each other the
LSR A chooses the interface identifier for link l, we call this identifiers they assign to the link. Exchanging the identifiers
the "outgoing interface identifier from LSR A's point of view". If may be accomplished by configuration, by means of a protocol such
there is a reverse link from LSR B to LSR A, B chooses the as LMP ([LMP]), by means of RSVP/CR-LDP (especially in the case
outgoing interface identifier for the reverse link, we call this where a link is a Forwarding Adjacency, see below), or by means of
the linkÆs "incoming interface identifier" from LSR AÆs point of IS-IS or OSPF extensions ([ISIS-GMPLS], [OSPF-GMPLS]).
view. There is no a priori relationship between the two interface
identifiers. Both ends must also agree on each of these Consider an (unnumbered) link between LSRs A and B. LSR A chooses
identifiers. an identifier for that link. So is LSR B. From A's perspective we
refer to the identifier that A assigned to the link as the "link
local identifier" (or just "local identifier"), and to the
identifier that B assigned to the link as the "link remote
identifier" (or just "remote identifier"). Likewise, from B's
perspective the identifier that B assigned to the link is the
local identifier, and the identifier that A assigned to the link
is the remote identifier.
The new Unnumbered Interface ID sub-object/sub-TLV for the ER The new Unnumbered Interface ID sub-object/sub-TLV for the ER
Object/TLV contains the Router ID of the LSR at the upstream end Object/TLV contains the Router ID of the LSR at the upstream end
of the unnumbered link and the outgoing interface identifier with of the unnumbered link and the outgoing interface identifier or
respect to that upstream LSR. the link local identifier with respect to that upstream LSR.
The new Unnumbered Interface ID sub-object/sub-TLV for the RR The new Unnumbered Interface ID sub-object for the RR Object
Object contains the outgoing interface identifier with respect to contains the outgoing interface identifier with respect to the LSR
the LSR that adds it in the RR Object. that adds it in the RR Object.
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B. The ability to carry (TE) information about unnumbered links in B. The ability to carry (TE) information about unnumbered links in
IGP TE extensions requires new sub-TLVs for the extended IS IGP TE extensions requires new sub-TLVs for the extended IS
reachability TLV defined in ISIS-TE and for the TE LSA (which is reachability TLV defined in ISIS-TE and for the TE LSA (which is
an opaque LSA) defined in OSPF-TE. An Outgoing Interface an opaque LSA) defined in OSPF-TE. A Link Local Identifier sub-TLV
Identifier sub-TLV and an Incoming Interface Identifier sub-TLV and a Link Remote Identifier sub-TLV are defined.
are defined.
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5.1. Unnumbered Forwarding Adjacencies 5.1. Unnumbered Forwarding Adjacencies
If an LSR that originates an LSP advertises this LSP as an If an LSR that originates an LSP advertises this LSP as an
unnumbered FA in IS-IS or OSPF, or the LSR uses this FA as an unnumbered FA in IS-IS or OSPF, or the LSR uses this FA as an
unnumbered component link of a bundled link, the LSR must allocate unnumbered component link of a bundled link, the LSR must allocate
an Interface ID to that FA. If the LSP is bi-directional, the tail an Interface ID to that FA. If the LSP is bi-directional, the tail
end does the same and allocates an Interface ID to the reverse FA. end does the same and allocates an Interface ID to the reverse FA.
Signaling has been enhanced to carry the Interface ID of a FA in the Signaling has been enhanced to carry the Interface ID of a FA in the
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must be advertised separately in order to be used, except if link must be advertised separately in order to be used, except if link
bundling is used. bundling is used.
When a pair of LSRs is connected by multiple links, it is possible When a pair of LSRs is connected by multiple links, it is possible
to advertise several (or all) of these links as a single link into to advertise several (or all) of these links as a single link into
OSPF and/or IS-IS. This process is called link bundling, or just OSPF and/or IS-IS. This process is called link bundling, or just
bundling. The resulting logical link is called a bundled link as its bundling. The resulting logical link is called a bundled link as its
physical links are called component links (and are identified by physical links are called component links (and are identified by
interface indexes). interface indexes).
It results that a combination of three identifiers ((bundled) link
identifier, component link identifier, label) is sufficient to
unambiguously identify the appropriate resources used by an LSP.
The purpose of link bundling is to improve routing scalability by The purpose of link bundling is to improve routing scalability by
reducing the amount of information that has to be handled by OSPF reducing the amount of information that has to be handled by OSPF
and/or IS-IS. This reduction is accomplished by performing and/or IS-IS. This reduction is accomplished by performing
information aggregation/abstraction. As with any other information information aggregation/abstraction. As with any other information
aggregation/abstraction, this results in losing some of the aggregation/abstraction, this results in losing some of the
information. To limit the amount of losses one need to restrict the information. To limit the amount of losses one need to restrict the
type of the information that can be aggregated/abstracted. type of the information that can be aggregated/abstracted.
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6.1. Restrictions on bundling 6.1. Restrictions on bundling
The following restrictions are required for bundling links. All The following restrictions are required for bundling links. All
component links in a bundle must begin and end on the same pair of component links in a bundle must begin and end on the same pair of
LSRs; and share some common characteristics or properties defined in LSRs; and share some common characteristics or properties defined in
[OSPF-TE] and [ISIS-TE], i.e. they must have the same: [OSPF-TE] and [ISIS-TE], i.e. they must have the same:
- Link Type (i.e. point-to-point or multi-access), - Link Type (i.e. point-to-point or multi-access),
- TE Metric (i.e. an administrative cost), - TE Metric (i.e. an administrative cost),
- Set of Resource Classes at each end of the links (i.e. colors). - Set of Resource Classes at each end of the links (i.e. colors).
E. Mannie et. al. Internet-Draft May 2002 15 Note that an FA may also be a component link. In fact, a bundle can
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001 consist of a mix of point-to-point links and FAs, but all sharing
some common properties.
Note that bundling may be applied recursively; a component link may
itself be a bundled link. An FA may also be a component link. In
fact, a bundle can consist of a mix of point-to-point links, FAs,
and bundled links, but all sharing some common properties.
6.2. Routing considerations for bundling 6.2. Routing considerations for bundling
A bundled link is just another kind of TE link such as those defined A bundled link is just another kind of TE link such as those defined
by [GMPLS-ROUTING]. The liveness of the bundled link is determined by [GMPLS-ROUTING]. The liveness of the bundled link is determined
by the liveness of each its component links, a bundled link is alive by the liveness of each its component links, a bundled link is alive
when at least one of its component links is alive. The liveness of a when at least one of its component links is alive. The liveness of a
component link can be determined by any of several means: IS-IS or component link can be determined by any of several means: IS-IS or
OSPF hellos over the component link, or RSVP Hello (hop local), or OSPF hellos over the component link, or RSVP Hello (hop local), or
LMP hellos (link local), or from layer 1 or layer 2 indications. LMP hellos (link local), or from layer 1 or layer 2 indications.
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Forming a bundled link consist in aggregating the identical TE Forming a bundled link consist in aggregating the identical TE
parameters of each individual component link to produce aggregated parameters of each individual component link to produce aggregated
TE parameters. A TE link as defined by [GMPLS-ROUTING] has many TE parameters. A TE link as defined by [GMPLS-ROUTING] has many
parameters, adequate aggregation rules must be defined for each one. parameters, adequate aggregation rules must be defined for each one.
Some parameters can be sums of component characteristics such as the Some parameters can be sums of component characteristics such as the
unreserved bandwidth and the maximum reservable bandwidth. Bandwidth unreserved bandwidth and the maximum reservable bandwidth. Bandwidth
information is an important part of a bundle advertisement and it information is an important part of a bundle advertisement and it
must be clearly defined since an abstraction is done. must be clearly defined since an abstraction is done.
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A GMPLS node with bundled links must apply admission control on a A GMPLS node with bundled links must apply admission control on a
per-component link basis. per-component link basis.
6.3. Signaling considerations 6.3. Signaling considerations
Typically, an LSP's explicit route (e.g. contained in an explicit Typically, an LSP's explicit route (e.g. contained in an explicit
route TLV/Object) will choose the bundled link to be used for the route TLV/Object) will choose the bundled link to be used for the
LSP, but not the component link(s), since information about the LSP, but not the component link(s), since information about the
bundled link is flooded, but information about the component links bundled link is flooded, but information about the component links
is not. is not.
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The choice of the component link to use is always made by an The choice of the component link to use is always made by an
upstream node. If the LSP is bidirectional, the upstream node upstream node. If the LSP is bidirectional, the upstream node
chooses a component link in each direction. chooses a component link in each direction.
Three mechanisms for indicating this choice to the downstream node Three mechanisms for indicating this choice to the downstream node
are possible. are possible.
6.3.1. Mechanism 1: Implicit Indication 6.3.1. Mechanism 1: Implicit Indication
This mechanism requires that each component link has a dedicated This mechanism requires that each component link has a dedicated
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With this mechanism, each component link that is unnumbered is With this mechanism, each component link that is unnumbered is
assigned a unique Interface Identifier (32 bits value). The upstream assigned a unique Interface Identifier (32 bits value). The upstream
node indicates the choice of the component link by including a new node indicates the choice of the component link by including a new
IF_ID RSVP_HOP object/IF_ID TLV in the Path/Label Request message IF_ID RSVP_HOP object/IF_ID TLV in the Path/Label Request message
[RSVP-TE-GMPLS] [CR-LDP-GMPLS]. [RSVP-TE-GMPLS] [CR-LDP-GMPLS].
This object/TLV carries the component interface ID in the downstream This object/TLV carries the component interface ID in the downstream
direction for a unidirectional LSP, and in addition the component direction for a unidirectional LSP, and in addition the component
interface ID in the upstream direction for a bi-directional LSP. interface ID in the upstream direction for a bi-directional LSP.
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The two LSRs at each end of the bundled link exchange these The two LSRs at each end of the bundled link exchange these
identifiers. Exchanging the identifiers may be accomplished by identifiers. Exchanging the identifiers may be accomplished by
configuration, by means of a protocol such as LMP (preferred configuration, by means of a protocol such as LMP (preferred
solution), by means of RSVP/CR-LDP (especially in the case where a solution), by means of RSVP/CR-LDP (especially in the case where a
component link is a Forwarding Adjacency), or by means of IS-IS or component link is a Forwarding Adjacency), or by means of IS-IS or
OSPF extensions. OSPF extensions.
This mechanism does not require each component link to have its own This mechanism does not require each component link to have its own
control channel. In fact, it doesn't even require the whole control channel. In fact, it doesn't even require the whole
(bundled) link to have its own control channel. (bundled) link to have its own control channel.
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6.4. Unnumbered Bundled Link 6.4. Unnumbered Bundled Link
A bundled link may itself be numbered or unnumbered independent of A bundled link may itself be numbered or unnumbered independent of
whether the component links are numbered or not. This affects how whether the component links are numbered or not. This affects how
the bundled link is advertised in IS-IS/OSPF, and the format of LSP the bundled link is advertised in IS-IS/OSPF, and the format of LSP
EROs that traverse the bundled link. Furthermore, unnumbered EROs that traverse the bundled link. Furthermore, unnumbered
Interface Identifiers for all unnumbered outgoing links of a given Interface Identifiers for all unnumbered outgoing links of a given
LSR (whether component links, Forwarding Adjacencies or bundled LSR (whether component links, Forwarding Adjacencies or bundled
links) must be unique in the context of that LSR. links) must be unique in the context of that LSR.
6.5. Forming TE links 6.5. Forming bundled links
The generic rule for bundling component links is to place those The generic rule for bundling component links is to place those
links that are correlated in some manner in the same bundle. If links that are correlated in some manner in the same bundle. If
links may be correlated based on multiple properties then the links may be correlated based on multiple properties then the
bundling may be applied sequentially based on these properties. For bundling may be applied sequentially based on these properties. For
instance, links may be first grouped based on the first property. instance, links may be first grouped based on the first property.
Each of these groups may be then divided into smaller groups based Each of these groups may be then divided into smaller groups based
on the second property and so on. The main principle followed in on the second property and so on. The main principle followed in
this process is that the properties of the resulting bundles should this process is that the properties of the resulting bundles should
be concisely summarizable. Link bundling may be done automatically be concisely summarizable. Link bundling may be done automatically
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link belonging to an SRLG that some link in the primary path belongs link belonging to an SRLG that some link in the primary path belongs
to. Thus, the rule to be followed is to group links belonging to to. Thus, the rule to be followed is to group links belonging to
exactly the same set of SRLGs. exactly the same set of SRLGs.
This type of sequential sub-division may result in a number of This type of sequential sub-division may result in a number of
bundles between two adjacent nodes. In practice, however, the link bundles between two adjacent nodes. In practice, however, the link
properties may not be very heterogeneous among component links properties may not be very heterogeneous among component links
between two adjacent nodes. Thus, the number of bundles in practice between two adjacent nodes. Thus, the number of bundles in practice
may not be large. may not be large.
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7. Relationship with the UNI 7. Relationship with the UNI
The interface between an edge GMPLS node and a GMPLS LSR on the The interface between an edge GMPLS node and a GMPLS LSR on the
network side may be referred to as a User to Network Interface network side may be referred to as a User to Network Interface
(UNI), while the interface between two network side LSRs may be (UNI), while the interface between two network side LSRs may be
referred to as a Network to Network Interface (NNI). referred to as a Network to Network Interface (NNI).
GMPLS does not specify separately a UNI and an NNI. Edge nodes are GMPLS does not specify separately a UNI and an NNI. Edge nodes are
connected to LSRs on the network side, and these LSRs are in turn connected to LSRs on the network side, and these LSRs are in turn
connected between them. Of course, the behavior of an edge node is connected between them. Of course, the behavior of an edge node is
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not exactly the same as the behavior of an LSR on the network side. not exactly the same as the behavior of an LSR on the network side.
Note also, that an edge node may run a routing protocol, however it Note also, that an edge node may run a routing protocol, however it
is expected that in most of the cases it will not (see also section is expected that in most of the cases it will not (see also section
7.2 and the section about signaling with an explicit route). 7.2 and the section about signaling with an explicit route).
Conceptually, a difference between UNI and NNI make sense either if Conceptually, a difference between UNI and NNI make sense either if
both interface uses completely different protocols, or if they use both interface uses completely different protocols, or if they use
the same protocols but with some outstanding differences. In the the same protocols but with some outstanding differences. In the
first case, separate protocols are often defined successively, with first case, separate protocols are often defined successively, with
more or less success. more or less success.
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Since the current OIF UNI interface does not cover photonic Since the current OIF UNI interface does not cover photonic
networks, G.709 Digital Wrapper, etc, it is from that perspective a networks, G.709 Digital Wrapper, etc, it is from that perspective a
subset of the GMPLS Architecture at the UNI. subset of the GMPLS Architecture at the UNI.
7.2. Reachability across the UNI 7.2. Reachability across the UNI
This section discusses the selection of an explicit route by an edge This section discusses the selection of an explicit route by an edge
node. The selection of the first LSR by an edge node connected to node. The selection of the first LSR by an edge node connected to
multiple LSRs is part of that problem. multiple LSRs is part of that problem.
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An edge node (host or LSR) can participate more or less deeply in An edge node (host or LSR) can participate more or less deeply in
the GMPLS routing. Four different routing models can be supported at the GMPLS routing. Four different routing models can be supported at
the UNI: configuration based, partial peering, silent listening and the UNI: configuration based, partial peering, silent listening and
full peering. full peering.
- Configuration based: this routing model requires the manual or - Configuration based: this routing model requires the manual or
automatic configuration of an edge node with a list of neighbor LSRs automatic configuration of an edge node with a list of neighbor LSRs
sorted by preference order. Automatic configuration can be achieved sorted by preference order. Automatic configuration can be achieved
using DHCP for instance. No routing information is exchanged at the using DHCP for instance. No routing information is exchanged at the
UNI, except maybe the ordered list of LSRs. The only routing UNI, except maybe the ordered list of LSRs. The only routing
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information used by the edge node is that list. The edge node sends information used by the edge node is that list. The edge node sends
by default an LSP request to the preferred LSR. ICMP redirects could by default an LSP request to the preferred LSR. ICMP redirects could
be send by this LSR to redirect some LSP requests to another LSR be send by this LSR to redirect some LSP requests to another LSR
connected to the edge node. GMPLS does not preclude that model. connected to the edge node. GMPLS does not preclude that model.
- Partial peering: limited routing information (mainly reachability) - Partial peering: limited routing information (mainly reachability)
can be exchanged across the UNI using some extensions in the can be exchanged across the UNI using some extensions in the
signaling plane. The reachability information exchanged at the UNI signaling plane. The reachability information exchanged at the UNI
may be used to initiate edge node specific routing decision over the may be used to initiate edge node specific routing decision over the
network. GMPLS does not have any capability to support this model network. GMPLS does not have any capability to support this model
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bundled links for routing purposes. Furthermore, to enable bundled links for routing purposes. Furthermore, to enable
communication between nodes for routing, signaling, and link communication between nodes for routing, signaling, and link
management, control channels must be established between a node management, control channels must be established between a node
pair. pair.
Link management is a collection of useful procedures between Link management is a collection of useful procedures between
adjacent nodes that provide local services such as control channel adjacent nodes that provide local services such as control channel
management, link connectivity verification, link property management, link connectivity verification, link property
correlation, and fault management. The Link Management Protocol correlation, and fault management. The Link Management Protocol
(LMP) has been defined to fulfill these operations. LMP was (LMP) has been defined to fulfill these operations. LMP was
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initiated in the context of GMPLS but is a generic toolbox that can initiated in the context of GMPLS but is a generic toolbox that can
be also used in other contexts. be also used in other contexts.
Control channel management and link property correlation are Control channel management and link property correlation are
mandatory procedures of LMP. Link connectivity verification and mandatory procedures of LMP. Link connectivity verification and
fault management are optional procedures. fault management are optional procedures.
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8.1. Control channel and control channel management 8.1. Control channel and control channel management
LMP control channel management is used to establish and maintain LMP control channel management is used to establish and maintain
control channels between nodes. Control channels exist independently control channels between nodes. Control channels exist independently
of TE links, and can be used to exchange MPLS control-plane of TE links, and can be used to exchange MPLS control-plane
information such as signaling, routing, and link management information such as signaling, routing, and link management
information. information.
An "LMP adjacency" is formed between two nodes that support the same An "LMP adjacency" is formed between two nodes that support the same
LMP capabilities. Multiple control channels may be active LMP capabilities. Multiple control channels may be active
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Each control channel individually negotiates its control channel Each control channel individually negotiates its control channel
parameters and maintains connectivity using a fast Hello protocol. parameters and maintains connectivity using a fast Hello protocol.
The latter is required if lower-level mechanisms are not available The latter is required if lower-level mechanisms are not available
to detect link failures. to detect link failures.
The Hello protocol of LMP is intended to be a lightweight keep-alive The Hello protocol of LMP is intended to be a lightweight keep-alive
mechanism that will react to control channel failures rapidly so mechanism that will react to control channel failures rapidly so
that IGP Hellos are not lost and the associated link-state that IGP Hellos are not lost and the associated link-state
adjacencies are not removed unnecessarily. adjacencies are not removed unnecessarily.
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The Hello protocol consists of two phases: a negotiation phase and a The Hello protocol consists of two phases: a negotiation phase and a
keep-alive phase. The negotiation phase allows negotiation of some keep-alive phase. The negotiation phase allows negotiation of some
basic Hello protocol parameters, like the Hello frequency. The keep- basic Hello protocol parameters, like the Hello frequency. The keep-
alive phase consists of a fast lightweight bi-directional Hello alive phase consists of a fast lightweight bi-directional Hello
message exchange. message exchange.
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If a group of control channels share a common node pair and support If a group of control channels share a common node pair and support
the same LMP capabilities, then LMP control channel messages (except the same LMP capabilities, then LMP control channel messages (except
Configuration messages, and Hello) may be transmitted over any of Configuration messages, and Hello) may be transmitted over any of
the active control channels without coordination between the local the active control channels without coordination between the local
and remote nodes. and remote nodes.
For LMP, it is essential that at least one control channel is always For LMP, it is essential that at least one control channel is always
available. In the event of a control channel failure, it may be available. In the event of a control channel failure, it may be
possible to use an alternate active control channel without possible to use an alternate active control channel without
coordination. coordination.
skipping to change at line 1220 skipping to change at line 1226
The verification procedure consists of sending Test messages in-band The verification procedure consists of sending Test messages in-band
over the data-bearing links. This requires that the unallocated over the data-bearing links. This requires that the unallocated
links must be opaque; however, multiple degrees of opaqueness (e.g., links must be opaque; however, multiple degrees of opaqueness (e.g.,
examining overhead bytes, terminating the payload, etc.), and hence examining overhead bytes, terminating the payload, etc.), and hence
different mechanisms to transport the Test messages, are specified. different mechanisms to transport the Test messages, are specified.
Note that the Test message is the only LMP message that is Note that the Test message is the only LMP message that is
transmitted over the link, and that Hello messages continue to be transmitted over the link, and that Hello messages continue to be
exchanged over the control channel during the link verification exchanged over the control channel during the link verification
process. Data-bearing links are tested in the transmit direction as process. Data-bearing links are tested in the transmit direction as
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they are unidirectional. As such, it is possible for LMP neighboring they are unidirectional. As such, it is possible for LMP neighboring
nodes to exchange the Test messages simultaneously in both nodes to exchange the Test messages simultaneously in both
directions. directions.
To initiate the link verification procedure, a node must first To initiate the link verification procedure, a node must first
notify the adjacent node that it will begin sending Test messages notify the adjacent node that it will begin sending Test messages
over a particular data-bearing link, or over the component links of over a particular data-bearing link, or over the component links of
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a particular bundled link. The node must also indicate the number of a particular bundled link. The node must also indicate the number of
data-bearing links that are to be verified; the interval at which data-bearing links that are to be verified; the interval at which
the test messages will be sent; the encoding scheme, the transport the test messages will be sent; the encoding scheme, the transport
mechanism that are supported, data rate for Test messages; and, in mechanism that are supported, data rate for Test messages; and, in
the case where the data-bearing links correspond to fibers, the the case where the data-bearing links correspond to fibers, the
wavelength over which the Test messages will be transmitted. wavelength over which the Test messages will be transmitted.
Furthermore, the local and remote bundled link identifiers are Furthermore, the local and remote bundled link identifiers are
transmitted at this time to perform the component link association transmitted at this time to perform the component link association
with the bundled link identifiers. with the bundled link identifiers.
skipping to change at line 1271 skipping to change at line 1277
procedure). procedure).
A downstream LMP neighbor that detects data link failures will send A downstream LMP neighbor that detects data link failures will send
an LMP message to its upstream neighbor notifying it of the failure. an LMP message to its upstream neighbor notifying it of the failure.
When an upstream node receives a failure notification, it can When an upstream node receives a failure notification, it can
correlate the failure with the corresponding input ports to correlate the failure with the corresponding input ports to
determine if the failure is between the two nodes. Once the failure determine if the failure is between the two nodes. Once the failure
has been localized, the signaling protocols can be used to initiate has been localized, the signaling protocols can be used to initiate
link or path protection/restoration procedures. link or path protection/restoration procedures.
E. Mannie et. al. Internet-Draft May 2002 23 8.5 LMP for DWDM Optical Line Systems (OLSs)
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
In an all-optical environment, LMP focuses on peer communications
(e.g. OXC-to-OXC). A great deal of information about a link between
two OXCs is known by the OLS (Optical Line System or WDM Terminal
multiplexer). Exposing this information to the control plane can
improve network usability by further reducing required manual
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configuration and also by greatly enhancing fault detection and
recovery.
LMP-WDM [LMP-WDM] defines extensions to LMP for use between and OXC
and an OLS. These extensions are intended to satisfy the Optical Link
Interface Requirements described in [OLI-REQ].
Fault detection is particularly an issue when the network is using
all-optical photonic switches (PXC). Once a connection is
established, PXCs have only limited visibility into the health of the
connection. Even though the PXC is all-optical, long-haul OLSs
typically terminate channels electrically and regenerate them
optically, which presents an opportunity to monitor the health of a
channel between PXCs. LMP-WDM can then be used by the OLS to provide
this information to the PXC.
In addition to the link information known to the OLS that is
exchanged through LMP-WDM, some information known to the OXC may also
be exchanged with the OLS through LMP-WDM. This information is useful
for alarm management and link monitoring (e.g. trace monitoring).
Alarm management is important because the administrative state of a
connection, known to the OXC (e.g. this information may be learned
through the Admin Status object of GMPLS signaling [GMPLS]), can be
used to suppress spurious alarms. For example, the OXC may know that
a connection is "up", "down", in a "testing" mode, or being deleted
("deletion-in-progress"). The OXC can use this information to inhibit
alarm reporting from the OLS when a connection is "down", "testing",
or being deleted.
It is important to note that an OXC may peer with one or more OLSs
and an OLS may peer with one or more OXCs. Although there are many
similarities between an OXC-OXC LMP session and an OXC-OLS LMP
session, particularly for control management and link verification,
there are some differences as well. These differences can primarily
be attributed to the nature of an OXC-OLS link, and the purpose of
OXC-OLS LMP sessions. The OXC-OXC links can be used to provide the
basis for GMPLS signaling and routing at the optical layer. The
information exchanged over LMP-WDM sessions is used to augment
knowledge about the links between OXCs.
In order for the information exchanged over the OXC-OLS LMP sessions
to be used by the OXC-OXC session, the information must be
coordinated by the OXC. However, the OXC-OXC and OXC-OLS LMP sessions
are run independently and must be maintained separately. One critical
requirement when running an OXC-OLS LMP session is the ability of the
OLS to make a data link transparent when not doing the verification
procedure. This is because the same data link may be verified between
OXC-OLS and between OXC-OXC. The verification procedure of LMP is
used to coordinate the Test procedure (and hence the
transparency/opaqueness of the data links). To maintain independence
between the sessions, it must be possible for the LMP sessions to
come up in any order. In particular, it must be possible for an OXC-
OXC LMP session to come up without an OXC-OLS LMP session being
brought up, and vice-versa.
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9. Generalized Signaling 9. Generalized Signaling
The GMPLS signaling extends certain base functions of the RSVP-TE The GMPLS signaling extends certain base functions of the RSVP-TE
and CR-LDP signaling and, in some cases, adds functionality. These and CR-LDP signaling and, in some cases, adds functionality. These
changes and additions impact basic LSP properties, how labels are changes and additions impact basic LSP properties, how labels are
requested and communicated, the unidirectional nature of LSPs, how requested and communicated, the unidirectional nature of LSPs, how
errors are propagated, and information provided for synchronizing errors are propagated, and information provided for synchronizing
the ingress and egress. the ingress and egress.
skipping to change at line 1326 skipping to change at line 1398
6. Bi-directional LSP establishment with contention 6. Bi-directional LSP establishment with contention
resolution. resolution.
7. Rapid failure notification extensions. 7. Rapid failure notification extensions.
8. Protection information currently focusing on link protection, 8. Protection information currently focusing on link protection,
plus primary and secondary LSP indication. plus primary and secondary LSP indication.
9. Explicit routing with explicit label control for a fine 9. Explicit routing with explicit label control for a fine
degree of control. degree of control.
10. Specific traffic parameters per technology. 10. Specific traffic parameters per technology.
11. LSP administrative status handling. 11. LSP administrative status handling.
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These building blocks will be described in mode details in the These building blocks will be described in mode details in the
following. A complete specification can be found in the following. A complete specification can be found in the
corresponding documents. corresponding documents.
Note that GMPLS is highly generic and has many options. Only Note that GMPLS is highly generic and has many options. Only
building blocks 1, 2 and 10 are mandatory, and only within the building blocks 1, 2 and 10 are mandatory, and only within the
specific format that is needed. Typically building blocks 6 and 9 specific format that is needed. Typically building blocks 6 and 9
should be implemented. Building blocks 3, 4, 5, 7, 8 and 11 are should be implemented. Building blocks 3, 4, 5, 7, 8 and 11 are
optional. optional.
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completed by the first/default LSR. completed by the first/default LSR.
The requested bandwidth is encoded in the RSVP-TE SENDER_TSPEC The requested bandwidth is encoded in the RSVP-TE SENDER_TSPEC
object, or in the CR-LDP Traffic Parameters TLV. Specific parameters object, or in the CR-LDP Traffic Parameters TLV. Specific parameters
for a given technology are given in these traffic parameters, such for a given technology are given in these traffic parameters, such
as the type of signal, concatenation and/or transparency for a as the type of signal, concatenation and/or transparency for a
SDH/SONET LSP. For some other technology there be could just one SDH/SONET LSP. For some other technology there be could just one
bandwidth parameter indicating the bandwidth as a floating-point bandwidth parameter indicating the bandwidth as a floating-point
value. value.
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The requested local protection per link may be requested using the The requested local protection per link may be requested using the
Protection Information Object/TLV. The end-to-end LSP protection is Protection Information Object/TLV. The end-to-end LSP protection is
for further study and is introduced LSP protection/restoration for further study and is introduced LSP protection/restoration
section (see after). section (see after).
If the LSP is a bi-directional LSP, an Upstream Label is also If the LSP is a bi-directional LSP, an Upstream Label is also
specified in the Path/Label Request message. This label will be the specified in the Path/Label Request message. This label will be the
one to use in the upstream direction. one to use in the upstream direction.
skipping to change at line 1427 skipping to change at line 1499
the LSP is returned. the LSP is returned.
9.2. Generalized Label Request 9.2. Generalized Label Request
The Generalized Label Request is a new object/TLV to be added in an The Generalized Label Request is a new object/TLV to be added in an
RSVP-TE Path message instead of the regular Label Request, or in a RSVP-TE Path message instead of the regular Label Request, or in a
CR-LDP Request message in addition to the already existing TLVs. CR-LDP Request message in addition to the already existing TLVs.
Only one label request can be used per message, so a single LSP can Only one label request can be used per message, so a single LSP can
be requested at a time per signaling message. be requested at a time per signaling message.
The Generalized Label Request gives two major characteristics The Generalized Label Request gives three major characteristics
(parameters) required to support the LSP being requested: the LSP (parameters) required to support the LSP being requested: the LSP
encoding type, and the LSP payload type called Generalized PID (G- Encoding Type, the Switching Type that must be used and the LSP
PID). payload type called Generalized PID (G-PID).
The LSP encoding type indicates the encoding type that will be used The LSP Encoding Type indicates the encoding type that will be used
with the data associated with the LSP, i.e. the type of technology with the data associated with the LSP, i.e. the type of technology
being considered. For instance, it can be SDH, SONET, Ethernet, ANSI being considered. For instance, it can be SDH, SONET, Ethernet, ANSI
PDH, etc. It represents the nature of the LSP, and not the nature of PDH, etc. It represents the nature of the LSP, and not the nature of
the links that the LSP traverses. This is used hop-by-hop by each the links that the LSP traverses. This is used hop-by-hop by each
node. node.
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A link may support a set of encoding formats, where support means A link may support a set of encoding formats, where support means
that a link is able to carry and switch a signal of one or more of that a link is able to carry and switch a signal of one or more of
these encoding formats. these encoding formats. The Switching Type indicates then the type
of switching that should be performed on a particular link for that
LSP. This information is needed for links that advertise more than
one type of switching capability.
Nodes must verify that the type indicated in the Switching Type is
supported on the corresponding incoming interface; otherwise the node
must generate a notification message with a "Routing
problem/Switching Type" indication.
The LSP payload type (G-PID) identifies the payload carried by the The LSP payload type (G-PID) identifies the payload carried by the
LSP, i.e. an identifier of the client layer of that LSP. For some LSP, i.e. an identifier of the client layer of that LSP. For some
technologies it also indicates the mapping used by the client layer, technologies it also indicates the mapping used by the client layer,
e.g. byte synchronous mapping of E1. This must be interpreted e.g. byte synchronous mapping of E1. This must be interpreted
according to the LSP encoding type of the LSP and is used by the according to the LSP encoding type of the LSP and is used by the
nodes at the endpoints of the LSP to know to which client layer a nodes at the endpoints of the LSP to know to which client layer a
request is destined, and in some cases by the penultimate hop. request is destined, and in some cases by the penultimate hop.
Other technology specific parameters are not transported in the Other technology specific parameters are not transported in the
skipping to change at line 1488 skipping to change at line 1568
- First, contiguous concatenation can be optionally applied on the - First, contiguous concatenation can be optionally applied on the
Elementary Signal, resulting in a contiguously concatenated Elementary Signal, resulting in a contiguously concatenated
signal. signal.
- Second, virtual concatenation can be optionally applied either - Second, virtual concatenation can be optionally applied either
directly on the elementary Signal, or on the contiguously directly on the elementary Signal, or on the contiguously
concatenated signal obtained from the previous phase. concatenated signal obtained from the previous phase.
- Third, some transparency can be optionally specified when - Third, some transparency can be optionally specified when
requesting a frame as signal rather than a container. Several requesting a frame as signal rather than a container. Several
transparency packages are defined. transparency packages are defined.
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- Fourth, a multiplication can be optionally applied either directly - Fourth, a multiplication can be optionally applied either directly
on the elementary Signal, or on the contiguously concatenated on the elementary Signal, or on the contiguously concatenated
signal obtained from the first phase, or on the virtually signal obtained from the first phase, or on the virtually
concatenated signal obtained from the second phase, or on these concatenated signal obtained from the second phase, or on these
signals combined with some transparency. signals combined with some transparency.
For RSVP-TE, the SONET/SDH traffic parameters are carried in a new For RSVP-TE, the SONET/SDH traffic parameters are carried in a new
SENDER_TSPEC and FLOWSPEC. The same format is used for both. There SENDER_TSPEC and FLOWSPEC. The same format is used for both. There
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is no Adspec associated with the SENDER_TSPEC, either it is omitted is no Adspec associated with the SENDER_TSPEC, either it is omitted
or a default value is used. The content of the FLOWSPEC object or a default value is used. The content of the FLOWSPEC object
received in a Resv message should be identical to the content of the received in a Resv message should be identical to the content of the
SENDER_TSPEC of the corresponding Path message. In other words, the SENDER_TSPEC of the corresponding Path message. In other words, the
receiver is normally not allowed to change the values of the traffic receiver is normally not allowed to change the values of the traffic
parameters. However some level of negotiation may be achieved as parameters. However some level of negotiation may be achieved as
explained in [SONETSDH-GMPLS] explained in [SONETSDH-GMPLS]
For CR-LDP, the SONET/SDH traffic parameters are simply carried in a For CR-LDP, the SONET/SDH traffic parameters are simply carried in a
new TLV. new TLV.
Note that a general discussion on SDH/SONET and GMPLS can be found
in [SDH/SONET-GMPLS-FRAMEWORK].
9.4. G.709 Traffic Parameters 9.4. G.709 Traffic Parameters
Simply said, an ITU-T G.709 based network is decomposed in two major Simply said, an ITU-T G.709 based network is decomposed in two major
layers: an optical layer (i.e. made of wavelengths) and a digital layers: an optical layer (i.e. made of wavelengths) and a digital
layer. These two layers are divided into sub-layers and switching layer. These two layers are divided into sub-layers and switching
occurs at two specific sub-layers: at the OCh (Optical Channel) occurs at two specific sub-layers: at the OCh (Optical Channel)
optical layer and at the ODU (Optical channel Data Unit) electrical optical layer and at the ODU (Optical channel Data Unit) electrical
layer. The ODUk notation is used to denotes ODUs at different layer. The ODUk notation is used to denotes ODUs at different
bandwidths. bandwidths.
skipping to change at line 1542 skipping to change at line 1625
be applied strictly in the following order: be applied strictly in the following order:
- First, virtual concatenation can be optionally applied directly on - First, virtual concatenation can be optionally applied directly on
the elementary Signal, the elementary Signal,
- Second, a multiplication can be optionally applied, either - Second, a multiplication can be optionally applied, either
directly on the elementary Signal, or on the virtually directly on the elementary Signal, or on the virtually
concatenated signal obtained from the first phase. concatenated signal obtained from the first phase.
Additional ODUk Multiplexing traffic parameters allow indicating an Additional ODUk Multiplexing traffic parameters allow indicating an
ODUk mapping (ODUj into ODUk) for an ODUk multiplexing LSP request. ODUk mapping (ODUj into ODUk) for an ODUk multiplexing LSP request.
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G.709 supports the following multiplexing capabilities: ODUj into G.709 supports the following multiplexing capabilities: ODUj into
ODUk (k > j); and ODU1 with ODU2 multiplexing into ODU3. ODUk (k > j); and ODU1 with ODU2 multiplexing into ODU3.
For RSVP-TE, the SONET/SDH traffic parameters are carried in a new For RSVP-TE, the SONET/SDH traffic parameters are carried in a new
SENDER-TSPEC and FLOWSPEC. The same format is used for both. There SENDER-TSPEC and FLOWSPEC. The same format is used for both. There
is no Adspec associated with the SENDER_TSPEC, either it is omitted is no Adspec associated with the SENDER_TSPEC, either it is omitted
or a default value is used. The content of the FLOWSPEC object or a default value is used. The content of the FLOWSPEC object
received in a Resv message should be identical to the content of the received in a Resv message should be identical to the content of the
SENDER_TSPEC of the corresponding Path message. SENDER_TSPEC of the corresponding Path message.
For CR-LDP, the SONET/SDH traffic parameters are simply carried in a For CR-LDP, the SONET/SDH traffic parameters are simply carried in a
new TLV. new TLV.
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9.5. Bandwidth Encoding 9.5. Bandwidth Encoding
Some technologies that do not have (yet) specific traffic parameters Some technologies that do not have (yet) specific traffic parameters
just require a bandwidth encoding transported in a generic form. just require a bandwidth encoding transported in a generic form.
Bandwidth is carried in 32-bit number in IEEE floating-point format Bandwidth is carried in 32-bit number in IEEE floating-point format
(the unit is bytes per second). Values are carried in a per protocol (the unit is bytes per second). Values are carried in a per protocol
specific manner. For non-packet LSPs, it is useful to define specific manner. For non-packet LSPs, it is useful to define
discrete values to identify the bandwidth of the LSP. discrete values to identify the bandwidth of the LSP.
It should be noted that this bandwidth encoding do not apply to It should be noted that this bandwidth encoding do not apply to
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label can be as simple as an integer value such as a wavelength label can be as simple as an integer value such as a wavelength
label or can be more elaborated such as an SDH/SONET or a G.709 label or can be more elaborated such as an SDH/SONET or a G.709
label. label.
SDH and SONET define each a multiplexing structure. These SDH and SONET define each a multiplexing structure. These
multiplexing structures will be used as naming trees to create multiplexing structures will be used as naming trees to create
unique labels. Such a label will identify the exact position (times- unique labels. Such a label will identify the exact position (times-
lot(s)) of a signal in a multiplexing structure. Since the SONET lot(s)) of a signal in a multiplexing structure. Since the SONET
multiplexing structure may be seen as a subset of the SDH multiplexing structure may be seen as a subset of the SDH
multiplexing structure, the same format of label is used for SDH and multiplexing structure, the same format of label is used for SDH and
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SONET. A similar concept is applied to build a label at the G.709 SONET. A similar concept is applied to build a label at the G.709
ODU layer. ODU layer.
Since the nodes sending and receiving the Generalized Label know Since the nodes sending and receiving the Generalized Label know
what kinds of link they are using, the Generalized Label does not what kinds of link they are using, the Generalized Label does not
identify its type, instead the nodes are expected to know from the identify its type, instead the nodes are expected to know from the
context what type of label to expect. context what type of label to expect.
A Generalized Label only carries a single level of label, i.e. it is A Generalized Label only carries a single level of label, i.e. it is
non-hierarchical. When multiple levels of labels (LSPs within LSPs) non-hierarchical. When multiple levels of labels (LSPs within LSPs)
are required, each LSP must be established separately. are required, each LSP must be established separately.
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9.7. Waveband Switching 9.7. Waveband Switching
A special case of wavelength switching is waveband switching. A A special case of wavelength switching is waveband switching. A
waveband represents a set of contiguous wavelengths, which can be waveband represents a set of contiguous wavelengths, which can be
switched together to a new waveband. For optimization reasons it may switched together to a new waveband. For optimization reasons it may
be desirable for a photonic cross-connect to optically switch be desirable for a photonic cross-connect to optically switch
multiple wavelengths as a unit. This may reduce the distortion on multiple wavelengths as a unit. This may reduce the distortion on
the individual wavelengths and may allow tighter separation of the the individual wavelengths and may allow tighter separation of the
individual wavelengths. A Waveband label is defined to support this individual wavelengths. A Waveband label is defined to support this
special case. special case.
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optical equipment where there may be a lengthy (in electrical terms) optical equipment where there may be a lengthy (in electrical terms)
delay in configuring the switching fabric. For example micro mirrors delay in configuring the switching fabric. For example micro mirrors
may have to be elevated or moved, and this physical motion and may have to be elevated or moved, and this physical motion and
subsequent damping takes time. If the labels and hence switching subsequent damping takes time. If the labels and hence switching
fabric are configured in the reverse direction (the norm) the fabric are configured in the reverse direction (the norm) the
MAPPING/Resv message may need to be delayed by 10's of milliseconds MAPPING/Resv message may need to be delayed by 10's of milliseconds
per hop in order to establish a usable forwarding path. It can be per hop in order to establish a usable forwarding path. It can be
important for restoration purposes where alternate LSPs may need to important for restoration purposes where alternate LSPs may need to
be rapidly established as a result of network failures. be rapidly established as a result of network failures.
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9.9. Label Restriction by the Upstream 9.9. Label Restriction by the Upstream
An upstream node can optionally restrict (limit) the choice of label An upstream node can optionally restrict (limit) the choice of label
of a downstream node to a set of acceptable labels. Giving lists of a downstream node to a set of acceptable labels. Giving lists
and/or ranges of inclusive (acceptable) or exclusive (unacceptable) and/or ranges of inclusive (acceptable) or exclusive (unacceptable)
labels in a Label Set provides this restriction. If not applied, all labels in a Label Set provides this restriction. If not applied, all
labels from the valid label range may be used. There are at least labels from the valid label range may be used. There are at least
four cases where a label restriction is useful in the "optical" four cases where a label restriction is useful in the "optical"
domain. domain.
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1. The first case is where the end equipment is only capable of 1. The first case is where the end equipment is only capable of
transmitting and receiving on a small specific set of transmitting and receiving on a small specific set of
wavelengths/bands. wavelengths/bands.
2. The second case is where there is a sequence of interfaces, which 2. The second case is where there is a sequence of interfaces, which
cannot support wavelength conversion and require the same wavelength cannot support wavelength conversion and require the same wavelength
be used end-to-end over a sequence of hops, or even an entire path. be used end-to-end over a sequence of hops, or even an entire path.
3. The third case is where it is desirable to limit the amount of 3. The third case is where it is desirable to limit the amount of
wavelength conversion being performed to reduce the distortion on wavelength conversion being performed to reduce the distortion on
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LSP. For a bi-directional LSPs, there is only one initiator and one LSP. For a bi-directional LSPs, there is only one initiator and one
terminator. terminator.
Normally to establish a bi-directional LSP when using [RSVP-TE] or Normally to establish a bi-directional LSP when using [RSVP-TE] or
[CR-LDP] two unidirectional paths must be independently established. [CR-LDP] two unidirectional paths must be independently established.
This approach has the following disadvantages: This approach has the following disadvantages:
1. The latency to establish the bi-directional LSP is equal to one 1. The latency to establish the bi-directional LSP is equal to one
round trip signaling time plus one initiator-terminator signaling round trip signaling time plus one initiator-terminator signaling
transit delay. This not only extends the setup latency for transit delay. This not only extends the setup latency for
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successful LSP establishment, but it extends the worst-case latency successful LSP establishment, but it extends the worst-case latency
for discovering an unsuccessful LSP to as much as two times the for discovering an unsuccessful LSP to as much as two times the
initiator-terminator transit delay. These delays are particularly initiator-terminator transit delay. These delays are particularly
significant for LSPs that are established for restoration purposes. significant for LSPs that are established for restoration purposes.
2. The control overhead is twice that of a unidirectional LSP. This 2. The control overhead is twice that of a unidirectional LSP. This
is because separate control messages (e.g. Path and Resv) must be is because separate control messages (e.g. Path and Resv) must be
generated for both segments of the bi-directional LSP. generated for both segments of the bi-directional LSP.
3. Because the resources are established in separate segments, route 3. Because the resources are established in separate segments, route
selection is complicated. There is also additional potential race selection is complicated. There is also additional potential race
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for conditions in assignment of resources, which decreases the for conditions in assignment of resources, which decreases the
overall probability of successfully establishing the bi-directional overall probability of successfully establishing the bi-directional
connection. connection.
4. It is more difficult to provide a clean interface for SDH/SONET 4. It is more difficult to provide a clean interface for SDH/SONET
equipment that may rely on bi-directional hop-by-hop paths for equipment that may rely on bi-directional hop-by-hop paths for
protection switching. Note that existing SDH/SONET gear transmits protection switching. Note that existing SDH/SONET gear transmits
the control information in-band with the data. the control information in-band with the data.
5. Bi-directional optical LSPs (or lightpaths) are seen as a 5. Bi-directional optical LSPs (or lightpaths) are seen as a
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that contention, basically the node with the higher node ID will win that contention, basically the node with the higher node ID will win
the contention. To reduce the probability of contention, some the contention. To reduce the probability of contention, some
mechanisms are also suggested. mechanisms are also suggested.
9.12. Rapid Notification of Failure 9.12. Rapid Notification of Failure
GMPLS defines several signaling extensions that enable expedited GMPLS defines several signaling extensions that enable expedited
notification of failures and other events to nodes responsible for notification of failures and other events to nodes responsible for
restoring failed LSPs, and error handling. restoring failed LSPs, and error handling.
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1. Acceptable Label Set for notification on Label Error: 1. Acceptable Label Set for notification on Label Error:
There are cases in traditional MPLS and in GMPLS that result in an There are cases in traditional MPLS and in GMPLS that result in an
error message containing an "Unacceptable label value" indication. error message containing an "Unacceptable label value" indication.
When these cases occur, it can useful for the node generating the When these cases occur, it can useful for the node generating the
error message to indicate which labels would be acceptable. To cover error message to indicate which labels would be acceptable. To cover
this case, GMPLS introduces the ability to convey such information this case, GMPLS introduces the ability to convey such information
via the "Acceptable Label Set". An Acceptable Label Set is carried via the "Acceptable Label Set". An Acceptable Label Set is carried
in appropriate protocol specific error messages. The format of an in appropriate protocol specific error messages. The format of an
Acceptable Label Set is identical to a Label Set. Acceptable Label Set is identical to a Label Set.
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2. Expedited notification: 2. Expedited notification:
Extensions to RSVP-TE enable expedited notification of failures and Extensions to RSVP-TE enable expedited notification of failures and
other events to determined nodes. For CR-LDP there is not currently other events to determined nodes. For CR-LDP there is not currently
a similar mechanism. The first extension identifies where event a similar mechanism. The first extension identifies where event
notifications are to be sent. The second provides for general notifications are to be sent. The second provides for general
expedited event notification with a Notify message. Such extensions expedited event notification with a Notify message. Such extensions
can be used by fast restoration mechanisms. Notifications may be can be used by fast restoration mechanisms. Notifications may be
requested in both the upstream and downstream directions. requested in both the upstream and downstream directions.
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routing protocols. Path computation algorithms may take this routing protocols. Path computation algorithms may take this
information into account when computing paths for setting up LSPs. information into account when computing paths for setting up LSPs.
Protection information also indicates if the LSP is a primary or Protection information also indicates if the LSP is a primary or
secondary LSP. A secondary LSP is a backup to a primary LSP. The secondary LSP. A secondary LSP is a backup to a primary LSP. The
resources of a secondary LSP are normally not used until the primary resources of a secondary LSP are normally not used until the primary
LSP fails, but they may be used by other LSPs until the primary LSP LSP fails, but they may be used by other LSPs until the primary LSP
fails over the secondary LSP. At that point, any LSP that is using fails over the secondary LSP. At that point, any LSP that is using
the resources for the secondary LSP must be preempted. the resources for the secondary LSP must be preempted.
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Six link protection types are currently defined as individual flags Six link protection types are currently defined as individual flags
and can be combined: enhanced, dedicated 1+1, dedicated 1:1, shared, and can be combined: enhanced, dedicated 1+1, dedicated 1:1, shared,
unprotected, extra traffic. See [GMPLS-SIG] section 7.1 for a unprotected, extra traffic. See [GMPLS-SIG] section 7.1 for a
precise definition of each. precise definition of each.
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9.14. Explicit Routing and Explicit Label Control 9.14. Explicit Routing and Explicit Label Control
Using an explicit route can control the path taken by an LSP more or By using an explicit route the path taken by an LSP can be
less precisely. Typically, the node at the head-end of an LSP finds controlled more or less precisely. Typically, the node at the head-
an explicit route and builds an Explicit Route Object (ERO)/ end of an LSP finds an explicit route and builds an Explicit Route
Explicit Route (ER) TLV that contains that route. Possibly, the edge Object (ERO)/ Explicit Route (ER) TLV that contains that route.
node does not build any explicit route, and just transmit a Possibly, the edge node does not build any explicit route, and just
signaling request to a default neighbor LSR (as IP/MPLS hosts transmit a signaling request to a default neighbor LSR (as IP/MPLS
would). For instance, an explicit route could be added to a hosts would). For instance, an explicit route could be added to a
signaling message by the first switching node, on behalf of the edge signaling message by the first switching node, on behalf of the edge
node. Note also that an explicit route is altered by intermediate node. Note also that an explicit route is altered by intermediate
LSRs during its progression towards the destination. LSRs during its progression towards the destination.
The explicit route is originally defined by MPLS-TE as a list of The explicit route is originally defined by MPLS-TE as a list of
abstract nodes (i.e. groups of nodes) along the explicit route. Each abstract nodes (i.e. groups of nodes) along the explicit route. Each
abstract node can be an IPv4 address prefix, an IPv6 address prefix, abstract node can be an IPv4 address prefix, an IPv6 address prefix,
or an AS number. This capability allows the generator of the or an AS number. This capability allows the generator of the
explicit route to have imperfect information about the details of explicit route to have incomplete information about the details of
the path. In the simplest case, an abstract node can be a full IP the path. In the simplest case, an abstract node can be a full IP
address (32 bits) that identifies a specific node (called a simple address (32 bits) that identifies a specific node (called a simple
abstract node). abstract node).
MPLS-TE allows strict and loose abstract nodes. The path between a MPLS-TE allows strict and loose abstract nodes. The path between a
strict node and its preceding node must include only network nodes strict node and its preceding node must include only network nodes
from the strict node and its preceding abstract node. The path from the strict node and its preceding abstract node. The path
between a loose node and its preceding node may include other between a loose node and its preceding abstract node may include
network nodes that are not part of the strict node or its preceding other network nodes that are not part of the loose node or its
abstract node. preceding abstract node.
This explicit route was extended to include interface numbers as This explicit route was extended to include interface numbers as
abstract nodes to support unnumbered interfaces; and further abstract nodes to support unnumbered interfaces; and further
extended by GMPLS to include labels as abstract nodes. Having labels extended by GMPLS to include labels as abstract nodes. Having labels
in an explicit route is an important feature that allows controlling in an explicit route is an important feature that allows controlling
the placement of an LSP with a very fine granularity. This is more the placement of an LSP with a very fine granularity. This is more
likely to be used for TDM, LSC and FSC links. likely to be used for TDM, LSC and FSC links.
In particular, the explicit label control in the explicit route In particular, the explicit label control in the explicit route
allows terminating an LSP on a particular outgoing port of an egress allows terminating an LSP on a particular outgoing port of an egress
node. Indeed, a label sub-object/TLV must follow a sub-object/TLV node. Indeed, a label sub-object/TLV must follow a sub-object/TLV
containing the IP address, or the interface identifier (in case of containing the IP address, or the interface identifier (in case of
unnumbered interface), associated with the link on which it is to be unnumbered interface), associated with the link on which it is to be
used. used.
This can also be used when it is desirable to "splice" two LSPs This can also be used when it is desirable to "splice" two LSPs
together, i.e. where the tail of the first LSP would be "spliced" together, i.e. where the tail of the first LSP would be "spliced"
into the head of the second LSP. into the head of the second LSP.
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Another use is when an optimization algorithm is used for an Another use is when an optimization algorithm is used for an
SDH/SONET network. This algorithm can provide very detailed explicit SDH/SONET network. This algorithm can provide very detailed explicit
routes, including the label (time-slot) to use on a link, in order routes, including the label (time-slot) to use on a link, in order
to minimize the fragmentation of the SDH/SONET multiplex on the to minimize the fragmentation of the SDH/SONET multiplex on the
corresponding interface. corresponding interface.
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9.15. Route recording 9.15. Route recording
In order to improve the reliability and the manageability of the LSP In order to improve the reliability and the manageability of the LSP
being established, the concept of the route recording was introduced being established, the concept of the route recording was introduced
in RSVP-TE to function as: in RSVP-TE to function as:
- First, a loop detection mechanism to discover L3 routing loops, or - First, a loop detection mechanism to discover L3 routing loops, or
loops inherent in the explicit route (this mechanism is strictly loops inherent in the explicit route (this mechanism is strictly
exclusive with the use of explicit routing objects). exclusive with the use of explicit routing objects).
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LSP modification consists in changing some LSP parameters, but LSP modification consists in changing some LSP parameters, but
normally without changing the route. It is supported using the same normally without changing the route. It is supported using the same
mechanism as re-routing. However, the semantic of LSP modification mechanism as re-routing. However, the semantic of LSP modification
will differ from one technology to the other. For instance, further will differ from one technology to the other. For instance, further
studies are required to understand the impact of dynamically studies are required to understand the impact of dynamically
changing some SDH/SONET circuit characteristics such as the changing some SDH/SONET circuit characteristics such as the
bandwidth, the protection type, the transparency, the concatenation, bandwidth, the protection type, the transparency, the concatenation,
etc. etc.
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9.17. LSP administrative status handling 9.17. LSP administrative status handling
GMPLS provides the optional capability to indicate the GMPLS provides the optional capability to indicate the
administrative status of an LSP by using a new Admin Status administrative status of an LSP by using a new Admin Status
object/TLV. Administrative Status Information is currently used in object/TLV. Administrative Status Information is currently used in
two ways. two ways.
In the first usage, Admin Status the object/TLV is carried in a In the first usage, Admin Status the object/TLV is carried in a
Path/Label Request or Resv/Label Mapping message to indicate the Path/Label Request or Resv/Label Mapping message to indicate the
administrative state of an LSP. In this usage, Administrative Status administrative state of an LSP. In this usage, Administrative Status
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Information indicates the state of the LSP, which include "up" or Information indicates the state of the LSP, which include "up" or
"down", if it in a "testing" mode, and if deletion is in progress. "down", if it in a "testing" mode, and if deletion is in progress.
Based on that administrative status, a node can take local Based on that administrative status, a node can take local
decisions, like to inhibit alarm reporting when an LSP is in "down" decisions, like to inhibit alarm reporting when an LSP is in "down"
or "testing" states, or to report alarms associated with the or "testing" states, or to report alarms associated with the
connection at a priority equal to or less than "Non service connection at a priority equal to or less than "Non service
affecting". affecting".
It is possible that some nodes along an LSP will not support the It is possible that some nodes along an LSP will not support the
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release of an LSP initiated by the ingress node. release of an LSP initiated by the ingress node.
9.18. Control channel separation 9.18. Control channel separation
In GMPLS, a control channel can be separated from the data channel. In GMPLS, a control channel can be separated from the data channel.
Indeed, the control channel can be implemented completely out-of- Indeed, the control channel can be implemented completely out-of-
band for various reasons, e.g. when the data channel cannot carry band for various reasons, e.g. when the data channel cannot carry
in-band control information. This issue was even originally in-band control information. This issue was even originally
introduced to MPLS in connection with link bundling. introduced to MPLS in connection with link bundling.
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In traditional MPLS there is an implicit one-to-one association of a In traditional MPLS there is an implicit one-to-one association of a
control channel to a data channel. When such an association is control channel to a data channel. When such an association is
present, no additional or special information is required to present, no additional or special information is required to
associate a particular LSP setup transaction with a particular data associate a particular LSP setup transaction with a particular data
channel. channel.
Otherwise it is necessary to convey additional information in Otherwise it is necessary to convey additional information in
signaling to identify the particular data channel being controlled. signaling to identify the particular data channel being controlled.
GMPLS supports explicit data channel identification by providing GMPLS supports explicit data channel identification by providing
interface identification information. GMPLS allows the use of a interface identification information. GMPLS allows the use of a
number of interface identification schemes including IPv4 or IPv6 number of interface identification schemes including IPv4 or IPv6
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addresses, interface indexes (for unnumbered interfaces) and addresses, interface indexes (for unnumbered interfaces) and
component interfaces (for bundled interfaces), unnumbered bunled component interfaces (for bundled interfaces), unnumbered bunled
interfaces are also supported. interfaces are also supported.
The choice of the data interface to use is always made by the sender The choice of the data interface to use is always made by the sender
of the Path/Label Request message, and indicated by including the of the Path/Label Request message, and indicated by including the
data channel's interface identifier in the message using a new data channel's interface identifier in the message using a new
RSVP_HOP object sub-type/Interface TLV. RSVP_HOP object sub-type/Interface TLV.
For bi-directional LSPs, the sender chooses the data interface in For bi-directional LSPs, the sender chooses the data interface in
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To improve scalability of MPLS TE (and thus GMPLS) it may be useful To improve scalability of MPLS TE (and thus GMPLS) it may be useful
to aggregate multiple TE LSPs inside a bigger TE LSP. Intermediate to aggregate multiple TE LSPs inside a bigger TE LSP. Intermediate
nodes see the external LSP only, they don't have to maintain nodes see the external LSP only, they don't have to maintain
forwarding states for each internal LSP, less signaling messages forwarding states for each internal LSP, less signaling messages
need to be exchanged and the external LSP can be somehow protected need to be exchanged and the external LSP can be somehow protected
instead (or in addition) to the internal LSPs. This can considerably instead (or in addition) to the internal LSPs. This can considerably
increase the scalability of the signaling. increase the scalability of the signaling.
The aggregation is accomplished by (a) an LSR creating a TE LSP, (b) The aggregation is accomplished by (a) an LSR creating a TE LSP, (b)
the LSR forming a forwarding adjacency out of that LSP (advertising the LSR forming a forwarding adjacency out of that LSP (advertising
this LSP as a unidirectional link into ISIS/OSPF), (c) allowing this LSP as a Traffic Engineering (TE) link into ISIS/OSPF), (c)
other LSRs to use forwarding adjacencies for their path computation, allowing other LSRs to use forwarding adjacencies for their path
and (d) nesting of LSPs originated by other LSRs into that LSP (e.g. computation, and (d) nesting of LSPs originated by other LSRs into
by using the label stack construct in the case of IP).
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that LSP (e.g. by using the label stack construct in the case of
IP).
An LSR may (under its local configuration control) announce an LSP An LSR may (under its local configuration control) announce an LSP
as a link into ISIS/OSPF. When this link is advertised into the as a TE link into ISIS/OSPF. When this link is advertised into the
same instance of ISIS/OSPF as the one that determines the route same instance of ISIS/OSPF as the one that determines the route
taken by the LSP, we call such a link a "forwarding adjacency" (FA). taken by the LSP, we call such a link a "forwarding adjacency" (FA).
We refer to the LSP as the "forwarding adjacency LSP", or just FA- We refer to the LSP as the "forwarding adjacency LSP", or just FA-
LSP. Note that since the advertised entity is a link in ISIS/OSPF, LSP. Note that since the advertised entity is a link in ISIS/OSPF,
both the endpoint LSRs of the FA-LSP must belong to the same ISIS both the endpoint LSRs of the FA-LSP must belong to the same ISIS
level/OSPF area (intra-area improvement of scalability). level/OSPF area (intra-area improvement of scalability).
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In general, creation/termination of a FA and its FA-LSP could be In general, creation/termination of a FA and its FA-LSP could be
driven either by mechanisms outside of MPLS (e.g., via configuration driven either by mechanisms outside of MPLS (e.g., via configuration
control on the LSR at the head-end of the adjacency), or by control on the LSR at the head-end of the adjacency), or by
mechanisms within MPLS (e.g., as a result of the LSR at the head-end mechanisms within MPLS (e.g., as a result of the LSR at the head-end
of the adjacency receiving LSP setup requests originated by some of the adjacency receiving LSP setup requests originated by some
other LSRs). other LSRs).
ISIS/OSPF floods the information about FAs just as it floods the ISIS/OSPF floods the information about FAs just as it floods the
information about any other links. As a result of this flooding, an information about any other links. As a result of this flooding, an
LSR has in its TE link state database the information about not just LSR has in its TE link state database the information about not just
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induced it, but may be bigger if only discrete bandwidths are induced it, but may be bigger if only discrete bandwidths are
available for the FA-LSP. In general, for dynamically provisioned available for the FA-LSP. In general, for dynamically provisioned
forwarding adjacencies, a policy-based mechanism may be needed to forwarding adjacencies, a policy-based mechanism may be needed to
associate attributes to forwarding adjacencies. associate attributes to forwarding adjacencies.
A FA advertisement could contain the information about the path A FA advertisement could contain the information about the path
taken by the FA-LSP associated with that FA. Other LSRs may use this taken by the FA-LSP associated with that FA. Other LSRs may use this
information for path computation. This information is carried in a information for path computation. This information is carried in a
new OSPF and IS-IS TLV called the Path TLV. new OSPF and IS-IS TLV called the Path TLV.
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It is possible that the underlying path information might change It is possible that the underlying path information might change
over time, via configuration updates, or dynamic route over time, via configuration updates, or dynamic route
modifications, resulting in the change of that TLV. modifications, resulting in the change of that TLV.
If forwarding adjacencies are bundled (via link bundling), and if If forwarding adjacencies are bundled (via link bundling), and if
the resulting bundled link carries a Path TLV, the underlying path the resulting bundled link carries a Path TLV, the underlying path
followed by each of the FA-LSPs that form the component links must followed by each of the FA-LSPs that form the component links must
be the same. be the same.
It is expected that forwarding adjacencies will not be used for It is expected that forwarding adjacencies will not be used for
establishing ISIS/OSPF peering relation between the routers at the establishing ISIS/OSPF peering relation between the routers at the
ends of the adjacency. ends of the adjacency.
E. Mannie et. al. Internet-Draft May 2002 38 LSP hierarchy could exist both with the peer and with the overlay
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001 models. With the peer model the LSP hierarchy is realized via FAs
and an LSP is both created and used as a TE link by exactly the same
instance of the control plane. Creating LSP hierarchy with overlays
doesn't involve the concept of FA. With the overlay model an LSP
created (and maintained) by one instance of the GMPLS control plane
is used as a TE link by another instance of the GMPLS control plane.
Moreover, the nodes using a TE link are expected to have a routing
and signaling adjacency.
10.2. Signaling aspects 10.2. Signaling aspects
For the purpose of processing the explicit route in a Path/Request For the purpose of processing the explicit route in a Path/Request
message of an LSP that is to be tunneled over a forwarding message of an LSP that is to be tunneled over a forwarding
adjacency, an LSR at the head-end of the FA-LSP views the LSR at the adjacency, an LSR at the head-end of the FA-LSP views the LSR at the
tail of that FA-LSP as adjacent (one IP hop away). tail of that FA-LSP as adjacent (one IP hop away).
10.3. Cascading of Forwarding Adjacencies 10.3. Cascading of Forwarding Adjacencies
skipping to change at line 2150 skipping to change at line 2245
Path computation may take into account region boundaries when Path computation may take into account region boundaries when
computing a path for an LSP. For example, path computation may computing a path for an LSP. For example, path computation may
restrict the path taken by an LSP to only the links whose restrict the path taken by an LSP to only the links whose
multiplexing/demultiplexing capability is PSC. When an LSP need to multiplexing/demultiplexing capability is PSC. When an LSP need to
cross a region boundary, it can trigger the establishment of an FA cross a region boundary, it can trigger the establishment of an FA
at the underlying layer (i.e. the L2SC layer). This can trigger a at the underlying layer (i.e. the L2SC layer). This can trigger a
cascading of FAs between layers with the following obvious order: cascading of FAs between layers with the following obvious order:
L2SC, then TDM, then LSC, and then finally FSC. L2SC, then TDM, then LSC, and then finally FSC.
11. Control Plane Fault Handling E. Mannie et. al. Internet-Draft September 2002 40
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
11. Routing and Signaling Adjacencies
By definition, two nodes have a routing (ISIS/OSPF) adjacency if
they are neighbors in the ISIS/OSPF sense.
By definition, two nodes have a signaling (RSVP-TE/CR-LDP) adjacency
if they are neighbors in the RSVP-TE/CR-LDP sense. Nodes A and B are
RSVP-TE neighbors if they directly exchange RSVP-TE messages
(Path/Resv) (e.g., as described in sections 7.1.1 and 7.1.2 of
[HIERARCHY]). The neighbor relationship includes exchanging RSVP-TE
Hellos.
By definition, a Forwarding Adjacency (FA) is a TE Link between two
GMPLS nodes whose path transits one or more other (G)MPLS nodes in
the same instance of the (G)MPLS control plane. If two nodes have
one or more non-FA TE Links between them, these two nodes are
expected (although not required) to have a routing adjacency. If two
nodes do not have any non-FA TE Links between them, it is expected
(although not required) that these two nodes would not have a
routing adjacency. To state the obvious, if the TE links between two
nodes are to be used for establishing LSPs, the two nodes must have
a signaling adjacency.
If one wants to establish routing and/or signaling adjacency between
two nodes, there must be an IP path between them. This IP path can
be, for example, a TE Link with an interface switching capability of
PSC, anything that looks likes an IP link (e.g., GRE tunnel, or a
(bi-directional) LSP that with an interface switching capability of
PSC).
A TE link may not be capable of being used directly for maintaining
routing and/or signaling adjacencies. This is because GMPLS routing
and signaling adjacencies requires exchanging data on a per (IP/ISO)
packet basis, and a TE link (e.g. a link between OXCs) may not be
capable of exchanging data on a per packet basis. In this case the
routing and signaling adjacencies are maintained via a set of one or
more control channels (see [LMP]).
Two nodes may have a TE link between them even if they don't have a
routing adjacency. Naturally, each node must run OSPF/ISIS with
GMPLS extensions in order for that TE link to be advertised. More
precisely, the node needs to run GMPLS extensions for TE Links with
an interface switching capability (see [GMPLS-ROUTING]) other than
PSC, and it needs to run either GMPLS or MPLS extensions for TE
links with an interface switching capability of PSC.
The mechanisms for Control Channel Separation [GMPLS-SIG] should be
used (even if the IP path between two nodes is a TE link). I.e.,
RSVP-TE/CR-LDP signaling should use the Interface_ID (IF_ID) object
to specify a particular TE link when establishing an LSP.
E. Mannie et. al. Internet-Draft September 2002 41
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The IP path could consist of multiple IP hops. In this case, the
mechanisms of sections 7.1.1 and 7.1.2 of [HIERARCHY] should be used
(in addition to Control Channel Separation).
12. Control Plane Fault Handling
There are two major types of faults that can impact a control plane. There are two major types of faults that can impact a control plane.
The first, referred to as control channel fault, relates to the case The first, referred to as control channel fault, relates to the case
where control communication is lost between two neighboring nodes. where control communication is lost between two neighboring nodes.
If the control channel is embedded with the data channel, data If the control channel is embedded with the data channel, data
channel recovery procedure should solve the problem. If the control channel recovery procedure should solve the problem. If the control
channel is independent of the data channel additional procedures are channel is independent of the data channel additional procedures are
required to recover from that problem. required to recover from that problem.
The second, referred to as nodal faults, relates to the case where a The second, referred to as nodal faults, relates to the case where a
skipping to change at line 2172 skipping to change at line 2328
loose its data forwarding state. loose its data forwarding state.
In transport networks, such types of control plane faults should not In transport networks, such types of control plane faults should not
have service impact on the existing connections. Under such have service impact on the existing connections. Under such
circumstances, a mechanism must exist to detect a control circumstances, a mechanism must exist to detect a control
communication failure and a recovery procedure must guarantee communication failure and a recovery procedure must guarantee
connection integrity at both ends of the control channel. connection integrity at both ends of the control channel.
For a control channel fault, once communication is restored routing For a control channel fault, once communication is restored routing
protocols are naturally able to recover but the underlying signaling protocols are naturally able to recover but the underlying signaling
E. Mannie et. al. Internet-Draft May 2002 39
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protocols must indicate that the nodes have maintained their state protocols must indicate that the nodes have maintained their state
through the failure. The signaling protocol must also ensure that through the failure. The signaling protocol must also ensure that
any state changes that were instantiated during the failure are any state changes that were instantiated during the failure are
synchronized between the nodes. synchronized between the nodes.
For a nodal fault, a node's control plane restarts and losses most For a nodal fault, a node's control plane restarts and losses most
of it's state information. In this case, both upstream and of it's state information. In this case, both upstream and
downstream nodes must synchronize their state information with the downstream nodes must synchronize their state information with the
restarted node. In order for any resynchronization to occur the node restarted node. In order for any resynchronization to occur the node
undergoing the restart will need to preserve some information, such undergoing the restart will need to preserve some information, such
skipping to change at line 2198 skipping to change at line 2350
These issues are addressed in protocol specific fashions, see [RSVP- These issues are addressed in protocol specific fashions, see [RSVP-
TE-GMPLS] and [CR-LDP-GMPLS]. Note that these cases only apply when TE-GMPLS] and [CR-LDP-GMPLS]. Note that these cases only apply when
there are mechanisms to detect data channel failures independent of there are mechanisms to detect data channel failures independent of
control channel failures. control channel failures.
The LDP Fault tolerant draft [LDP-FT] specifies the procedures to The LDP Fault tolerant draft [LDP-FT] specifies the procedures to
recover from a control channel failure. [RSVP-TE-GMPLS] specifies recover from a control channel failure. [RSVP-TE-GMPLS] specifies
how to recover from both a control channel failure and a node how to recover from both a control channel failure and a node
failure. failure.
12. LSP Protection and Restoration E. Mannie et. al. Internet-Draft September 2002 42
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13. LSP Protection and Restoration
This section discusses Protection and Restoration (P&R) issues for This section discusses Protection and Restoration (P&R) issues for
GMPLS LSPs. It is driven by the requirements outlined in [TEWG- GMPLS LSPs. It is driven by the requirements outlined in [TEWG-
RESTORE] and some of the principles outlined in [MPLS-RECOVERY]. It RESTORE] and some of the principles outlined in [MPLS-RECOVERY]. It
will be enhanced, as more GMPLS P&R mechanisms are defined. The will be enhanced, as more GMPLS P&R mechanisms are defined. The
scope of this section is clarified hereafter: scope of this section is clarified hereafter:
- This section is only applicable when a fault impacting LSP(s) - This section is only applicable when a fault impacting LSP(s)
happens in the data/transport plane. Section 11 deals with control happens in the data/transport plane. Section 11 deals with control
plane fault handling for nodal and control channel faults. plane fault handling for nodal and control channel faults.
skipping to change at line 2230 skipping to change at line 2385
- This section focuses on intra-layer P&R (horizontal hierarchy as - This section focuses on intra-layer P&R (horizontal hierarchy as
defined in [TEWG-RESTORE]) as opposed to the inter-layer P&R defined in [TEWG-RESTORE]) as opposed to the inter-layer P&R
(vertical hierarchy). (vertical hierarchy).
- P&R mechanisms are in general designed to handle single failures, - P&R mechanisms are in general designed to handle single failures,
which makes SRLG diversity a necessity. Recovery from multiple which makes SRLG diversity a necessity. Recovery from multiple
failures requires further study. failures requires further study.
- Both mesh and ring like topologies are supported. - Both mesh and ring like topologies are supported.
E. Mannie et. al. Internet-Draft May 2002 40
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In the following, we assume that: In the following, we assume that:
- TDM, LSC and FSC devices are more generally committing recovery - TDM, LSC and FSC devices are more generally committing recovery
resources in a non best effort way. Recovery resources are either resources in a non best effort way. Recovery resources are either
allocated and used, or at least logically reserved (used or not by allocated and used, or at least logically reserved (used or not by
preemptable extra traffic but unavailable anyway for regular preemptable extra traffic but unavailable anyway for regular
working traffic). working traffic).
- Shared P&R mechanisms are valuable to operators in order to - Shared P&R mechanisms are valuable to operators in order to
maximize their network utilization. maximize their network utilization.
- Sending preemptable excess traffic on recovery resources is a - Sending preemptable excess traffic on recovery resources is a
valuable feature for operators. valuable feature for operators.
12.1. Protection escalation across domains and layers 13.1. Protection escalation across domains and layers
To describe the P&R architecture, one must consider two dimensions To describe the P&R architecture, one must consider two dimensions
of hierarchy [TE-RESTORE]: of hierarchy [TE-RESTORE]:
- A horizontal hierarchy consisting of multiple P&R domains, which - A horizontal hierarchy consisting of multiple P&R domains, which
is important in an LSP based protection scheme. The scope of P&R is important in an LSP based protection scheme. The scope of P&R
E. Mannie et. al. Internet-Draft September 2002 43
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
may extend over a link (or span), an administrative domain or sub- may extend over a link (or span), an administrative domain or sub-
network, an entire LSP. network, an entire LSP.
An administrative domain may consist of a single P&R domain or as An administrative domain may consist of a single P&R domain or as
a concatenation of several smaller P&R domains. The operator can a concatenation of several smaller P&R domains. The operator can
configure P&R domains, based on customers' requirements, and on configure P&R domains, based on customers' requirements, and on
network topology and traffic engineering constraints. network topology and traffic engineering constraints.
- A vertical hierarchy consisting of multiple layers of P&R with - A vertical hierarchy consisting of multiple layers of P&R with
varying granularities (packet flows, STS trails, lightpaths, varying granularities (packet flows, STS trails, lightpaths,
skipping to change at line 2286 skipping to change at line 2442
schemes are more expedient, and therefore we can inhibit or hold schemes are more expedient, and therefore we can inhibit or hold
off higher-level P&R. The Top-down approach attempts service P&R off higher-level P&R. The Top-down approach attempts service P&R
at the higher levels before invoking "lower level" P&R. Higher- at the higher levels before invoking "lower level" P&R. Higher-
layer P&R is service selective, and permits "per-CoS" or "per-LSP" layer P&R is service selective, and permits "per-CoS" or "per-LSP"
re-routing. re-routing.
SLA's between network operators and their clients are needed to SLA's between network operators and their clients are needed to
determine the necessary timescales for P&R at each layer and at each determine the necessary timescales for P&R at each layer and at each
domain. domain.
E. Mannie et. al. Internet-Draft May 2002 41 13.2. Mapping of Services to P&R Resources
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
12.2. Mapping of Services to P&R Resources
The choice of a P&R scheme is a tradeoff between network utilization The choice of a P&R scheme is a tradeoff between network utilization
(cost) and service interruption time. In light of this tradeoff, (cost) and service interruption time. In light of this tradeoff,
network service providers are expected to support a range of network service providers are expected to support a range of
different service offerings or service levels. different service offerings or service levels.
One can classify LSPs into one of a small set of service levels. One can classify LSPs into one of a small set of service levels.
Among other things, these service levels define the reliability Among other things, these service levels define the reliability
characteristics of the LSP. The service level associated with a characteristics of the LSP. The service level associated with a
given LSP is mapped to one or more P&R schemes during LSP given LSP is mapped to one or more P&R schemes during LSP
skipping to change at line 2311 skipping to change at line 2464
different P&E schemes in different segments of a network (e.g. some different P&E schemes in different segments of a network (e.g. some
links may be span protected, whilst other segments of the LSP may links may be span protected, whilst other segments of the LSP may
utilize ring protection). These details are likely to be service utilize ring protection). These details are likely to be service
provider specific. provider specific.
An alternative to using service levels is for an application to An alternative to using service levels is for an application to
specify the set of specific P&R mechanisms to be used when specify the set of specific P&R mechanisms to be used when
establishing the LSP. This allows greater flexibility in using establishing the LSP. This allows greater flexibility in using
different mechanisms to meet the application requirements. different mechanisms to meet the application requirements.
E. Mannie et. al. Internet-Draft September 2002 44
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
A differentiator between these service levels is service A differentiator between these service levels is service
interruption time in the event of network failures, which is defined interruption time in the event of network failures, which is defined
as the length of time between when a failure occurs and when as the length of time between when a failure occurs and when
connectivity is re-established. The choice of service level (or P&R connectivity is re-established. The choice of service level (or P&R
scheme) should be dictated by the service requirements of different scheme) should be dictated by the service requirements of different
applications. applications.
12.3. Classification of P&R mechanism characteristics 13.3. Classification of P&R mechanism characteristics
The following figure provides a classification of the possible The following figure provides a classification of the possible
provisioning types of recovery LSPs, and of the levels of provisioning types of recovery LSPs, and of the levels of
overbooking that is possible for them. overbooking that is possible for them.
+ Computed on +Established +--Resources pre + Computed on +Established +--Resources pre
| demand | on demand | allocated | demand | on demand | allocated
Recovery LSP | | | Recovery LSP | | |
Provisioning -+ Pre computed +Pre established +--Resources Provisioning -+ Pre computed +Pre established +--Resources
allocated on allocated on
demand demand
+--Dedicated - 1:1, 1 +--Dedicated - 1:1, 1
| |
| |
+-- Shared - 1:N, Ring, Shared mesh +-- Shared - 1:N, Ring, Shared mesh
Level of | Level of |
Overbooking ---+-- Best effort Overbooking ---+-- Best effort
E. Mannie et. al. Internet-Draft May 2002 42 13.4. Different Stages in P&R
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12.4. Different Stages in P&R
Recovery from a network fault or impairment takes place in several Recovery from a network fault or impairment takes place in several
stages as discussed in [MPLS-RECOVERY], including fault detection, stages as discussed in [MPLS-RECOVERY], including fault detection,
fault localization, notification, recovery (i.e. the P&R itself) and fault localization, notification, recovery (i.e. the P&R itself) and
restoral (i.e. returning the traffic to the original working LSP or restoral (i.e. returning the traffic to the original working LSP or
to a new one) of traffic. to a new one) of traffic.
- Fault detection is technology and implementation dependent. In - Fault detection is technology and implementation dependent. In
general, failures are detected by lower layer mechanisms (e.g. general, failures are detected by lower layer mechanisms (e.g.
SONET/SDH, Loss-of-Light (LOL)). When a node detects a failure, an SONET/SDH, Loss-of-Light (LOL)). When a node detects a failure, an
skipping to change at line 2365 skipping to change at line 2518
- Fault localization can be done with the help of GMPLS, e.g. using - Fault localization can be done with the help of GMPLS, e.g. using
LMP for fault localization (see section 8.4). LMP for fault localization (see section 8.4).
- Fault notification can also be achieved through GMPLS, e.g. using - Fault notification can also be achieved through GMPLS, e.g. using
GMPLS RSVP-TE/CR-LDP notification (see section 9.12). GMPLS RSVP-TE/CR-LDP notification (see section 9.12).
- This section focuses on the different mechanisms available for - This section focuses on the different mechanisms available for
recovery and restoral of traffic once fault detection, recovery and restoral of traffic once fault detection,
localization and notification have taken place. localization and notification have taken place.
12.5. Recovery Strategies E. Mannie et. al. Internet-Draft September 2002 45
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13.5. Recovery Strategies
Network P&R techniques can be divided into Protection and Network P&R techniques can be divided into Protection and
Restoration. In protection, resources between the protection Restoration. In protection, resources between the protection
endpoints are established before failure, and connectivity after endpoints are established before failure, and connectivity after
failure is achieved simply by switching performed at the protection failure is achieved simply by switching performed at the protection
end-points. In contrast, restoration uses signaling after failure to end-points. In contrast, restoration uses signaling after failure to
allocate resources along the recovery path. allocate resources along the recovery path.
- Protection aims at extremely fast reaction times and may rely on - Protection aims at extremely fast reaction times and may rely on
the use of overhead control fields for achieving end-point the use of overhead control fields for achieving end-point
skipping to change at line 2394 skipping to change at line 2550
In addition, P&R can be applied on a local or end-to-end basis. In In addition, P&R can be applied on a local or end-to-end basis. In
the local approach, P&R is focused on the local proximity of the the local approach, P&R is focused on the local proximity of the
fault in order to reduce delay in restoring service. In the end-to- fault in order to reduce delay in restoring service. In the end-to-
end approach, the LSP originating and terminating nodes control end approach, the LSP originating and terminating nodes control
recovery. recovery.
Using these strategies, the following recovery mechanisms can be Using these strategies, the following recovery mechanisms can be
defined. defined.
E. Mannie et. al. Internet-Draft May 2002 43
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Editor's note: for each mechanism hereafter, it is intended to add Editor's note: for each mechanism hereafter, it is intended to add
references to the appropriate GMPLS and/or technology specific references to the appropriate GMPLS and/or technology specific
mechanisms. mechanisms.
12.6. Recovery mechanisms: Protection schemes 13.6. Recovery mechanisms: Protection schemes
Note that protection schemes are usually defined in technology Note that protection schemes are usually defined in technology
specific ways, but this does not preclude other solutions. specific ways, but this does not preclude other solutions.
- 1+1 Link Protection: Two pre-provisioned resources are used in - 1+1 Link Protection: Two pre-provisioned resources are used in
parallel. For example, data is transmitted simultaneously on two parallel. For example, data is transmitted simultaneously on two
parallel links and a selector is used at the receiving node to parallel links and a selector is used at the receiving node to
choose the best source. [Mechanisms reference to be added]. choose the best source. [Mechanisms reference to be added].
- 1:N Link Protection: Working and protecting resources (N working, - 1:N Link Protection: Working and protecting resources (N working,
1 backup) are pre-provisioned. If a working resource fails, the 1 backup) are pre-provisioned. If a working resource fails, the
data is switched to the protecting resource, using a coordination data is switched to the protecting resource, using a coordination
mechanism (e.g. in overhead bytes). More generally, N working and mechanism (e.g. in overhead bytes). More generally, N working and
M protecting resources can be assigned for M:N link protection. M protecting resources can be assigned for M:N link protection.
[Mechanisms reference to be added]. [Mechanisms reference to be added].
- Enhanced Protection: Various mechanisms such as protection rings - Enhanced Protection: Various mechanisms such as protection rings
can be used to enhance the level of protection beyond single link can be used to enhance the level of protection beyond single link
failures to include the ability to switch around a node failure or failures to include the ability to switch around a node failure or
multiple link failures within a span, based on a pre-established multiple link failures within a span, based on a pre-established
E. Mannie et. al. Internet-Draft September 2002 46
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topology of protection resources. [Mechanisms reference to be topology of protection resources. [Mechanisms reference to be
added]. added].
- 1+1 LSP Protection: Simultaneous data transmission on working and - 1+1 LSP Protection: Simultaneous data transmission on working and
protecting LSPs and tail-end selection can be applied. [Mechanisms protecting LSPs and tail-end selection can be applied. [Mechanisms
reference to be added]. reference to be added].
12.7. Recovery mechanisms: Restoration schemes 13.7. Recovery mechanisms: Restoration schemes
Restoration is possible thanks to the use of a distributed control Restoration is possible thanks to the use of a distributed control
plane like GMPLS in multiple of tenths of ms. It is much harder to plane like GMPLS in multiple of tenths of ms. It is much harder to
achieve when only an NMS is used, and can only be done in that case achieve when only an NMS is used, and can only be done in that case
in a multiple of seconds. in a multiple of seconds.
- End-to-end LSP restoration with re-provisioning: An end-to-end - End-to-end LSP restoration with re-provisioning: An end-to-end
restoration path is established after failure. The restoration restoration path is established after failure. The restoration
path may be dynamically calculated after failure, or pre- path may be dynamically calculated after failure, or pre-
calculated before failure (often during LSP establishment). calculated before failure (often during LSP establishment).
skipping to change at line 2452 skipping to change at line 2609
result, there is no guarantee that a given restoration path is result, there is no guarantee that a given restoration path is
available when a failure occurs. Thus one may have to crankback to available when a failure occurs. Thus one may have to crankback to
search for an available path. [Mechanisms reference to be added]. search for an available path. [Mechanisms reference to be added].
- End-to-end LSP restoration with pre-signaled recovery bandwidth - End-to-end LSP restoration with pre-signaled recovery bandwidth
reservation and no label pre-selection: An end-to-end restoration reservation and no label pre-selection: An end-to-end restoration
path is pre-calculated before failure and a signaling message is path is pre-calculated before failure and a signaling message is
sent along this pre-selected path to reserve bandwidth, but labels sent along this pre-selected path to reserve bandwidth, but labels
are not selected. [Mechanisms reference to be added]. are not selected. [Mechanisms reference to be added].
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The resources reserved on each link of a restoration path may be The resources reserved on each link of a restoration path may be
shared across different working LSPs that are not expected to fail shared across different working LSPs that are not expected to fail
simultaneously. Local node policies can be applied to define the simultaneously. Local node policies can be applied to define the
degree to which capacity is shared across independent failures. degree to which capacity is shared across independent failures.
Upon failure detection, LSP signaling is initiated along the Upon failure detection, LSP signaling is initiated along the
restoration path to select labels, and to initiate the appropriate restoration path to select labels, and to initiate the appropriate
cross-connections. [Mechanisms reference to be added]. cross-connections. [Mechanisms reference to be added].
- End-to-end LSP restoration with pre-signaled recovery bandwidth - End-to-end LSP restoration with pre-signaled recovery bandwidth
reservation and label pre-selection: An end-to-end restoration reservation and label pre-selection: An end-to-end restoration
skipping to change at line 2479 skipping to change at line 2633
to fail simultaneously. In networks based on TDM, LSC and FSC to fail simultaneously. In networks based on TDM, LSC and FSC
technology, LSP signaling is used after failure detection to technology, LSP signaling is used after failure detection to
establish cross-connections at the intermediate switches on the establish cross-connections at the intermediate switches on the
restoration path using the pre-selected labels. [Mechanisms restoration path using the pre-selected labels. [Mechanisms
reference to be added]. reference to be added].
- Local LSP restoration: the above approaches can be applied on a - Local LSP restoration: the above approaches can be applied on a
local basis rather than end-to-end, in order to reduce recovery local basis rather than end-to-end, in order to reduce recovery
time. [Mechanisms reference to be added]. time. [Mechanisms reference to be added].
12.8. Schema selection criteria E. Mannie et. al. Internet-Draft September 2002 47
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13.8. Schema selection criteria
This section discusses criteria that could be used by the operator This section discusses criteria that could be used by the operator
in order to make a choice among the various P&R mechanisms. in order to make a choice among the various P&R mechanisms.
- Robustness: In general, the less pre-planning of the restoration - Robustness: In general, the less pre-planning of the restoration
path, the more robust the restoration scheme is to a variety of path, the more robust the restoration scheme is to a variety of
failures, provided that adequate resources are available. failures, provided that adequate resources are available.
Restoration schemes with pre-planned paths, will not be able to Restoration schemes with pre-planned paths, will not be able to
recover from network failures that simultaneously affect both the recover from network failures that simultaneously affect both the
working and restoration paths. Thus, these paths should ideally be working and restoration paths. Thus, these paths should ideally be
skipping to change at line 2508 skipping to change at line 2665
that affect two LSPs that are sharing a label at a common node that affect two LSPs that are sharing a label at a common node
along their restoration routes, then only one of these LSPs can be along their restoration routes, then only one of these LSPs can be
recovered, unless the label assignment is changed. recovered, unless the label assignment is changed.
The robustness of a restoration scheme is also determined by the The robustness of a restoration scheme is also determined by the
amount of reserved restoration bandwidth - as the amount of amount of reserved restoration bandwidth - as the amount of
restoration bandwidth sharing increases (reserved bandwidth restoration bandwidth sharing increases (reserved bandwidth
decreases), the restoration scheme becomes less robust to decreases), the restoration scheme becomes less robust to
failures. Restoration schemes with pre-signaled bandwidth failures. Restoration schemes with pre-signaled bandwidth
reservation (with or without label pre-selection) can reserve reservation (with or without label pre-selection) can reserve
E. Mannie et. al. Internet-Draft May 2002 45
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adequate bandwidth to ensure recovery from any specific set of adequate bandwidth to ensure recovery from any specific set of
failure events, such as any single SRLG failure, any two SRLG failure events, such as any single SRLG failure, any two SRLG
failures etc. Clearly, more restoration capacity is allocated if a failures etc. Clearly, more restoration capacity is allocated if a
greater degree of failure recovery is required. Thus, the degree greater degree of failure recovery is required. Thus, the degree
to which the network is protected is determined by the policy that to which the network is protected is determined by the policy that
defines the amount of reserved restoration bandwidth. defines the amount of reserved restoration bandwidth.
- Recovery time: In general, the more pre-planning of the - Recovery time: In general, the more pre-planning of the
restoration route, the more rapid the P&R scheme. Protection restoration route, the more rapid the P&R scheme. Protection
schemes generally recover faster than restoration schemes. schemes generally recover faster than restoration schemes.
skipping to change at line 2537 skipping to change at line 2690
Recovery time objectives for SONET/SDH protection switching (not Recovery time objectives for SONET/SDH protection switching (not
including time to detect failure) are specified in [G.841] at 50 including time to detect failure) are specified in [G.841] at 50
ms, taking into account constraints on distance, number of ms, taking into account constraints on distance, number of
connections involved, and in the case of ring enhanced protection, connections involved, and in the case of ring enhanced protection,
number of nodes in the ring. number of nodes in the ring.
Recovery time objectives for restoration mechanisms are being Recovery time objectives for restoration mechanisms are being
defined through a separate effort [TE-RESTORE]. defined through a separate effort [TE-RESTORE].
E. Mannie et. al. Internet-Draft September 2002 48
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
- Resource Sharing: 1+1 and 1:N link and LSP protection require - Resource Sharing: 1+1 and 1:N link and LSP protection require
dedicated recovery paths with limited ability to share resources: dedicated recovery paths with limited ability to share resources:
1+1 allows no sharing, 1:N allows some sharing of protection 1+1 allows no sharing, 1:N allows some sharing of protection
resources and support of extra (preemptable) traffic. Flexibility resources and support of extra (preemptable) traffic. Flexibility
is limited because of topology restrictions, e.g. fixed ring is limited because of topology restrictions, e.g. fixed ring
topology for traditional enhanced protection schemes. topology for traditional enhanced protection schemes.
The degree to which restoration schemes allow sharing amongst The degree to which restoration schemes allow sharing amongst
multiple independent failures is directly dictated by the size of multiple independent failures is directly dictated by the size of
the restoration pool. In restoration schemes with re-provisioning, the restoration pool. In restoration schemes with re-provisioning,
a pool of restoration capacity can be defined from which all a pool of restoration capacity can be defined from which all
restoration routes are selected after failure. Thus, the degree of restoration routes are selected after failure. Thus, the degree of
sharing is defined by the amount of available restoration sharing is defined by the amount of available restoration
capacity. In restoration with pre-signaled bandwidth reservation, capacity. In restoration with pre-signaled bandwidth reservation,
the amount of reserved restoration capacity is determined by the the amount of reserved restoration capacity is determined by the
local bandwidth reservation policies. In all restoration schemes, local bandwidth reservation policies. In all restoration schemes,
pre-emptable resources can use spare restoration capacity when pre-emptable resources can use spare restoration capacity when
that capacity is not being used for failure recovery. that capacity is not being used for failure recovery.
13. Network Management 14. Network Management
Service Providers (SPs) use network management extensively to Service Providers (SPs) use network management extensively to
configure, monitor or provision various devices in their network. It configure, monitor or provision various devices in their network. It
is important to note that a SPÆs equipment may be distributed across is important to note that a SPÆs equipment may be distributed across
geographically separate sites, making distributed management even geographically separate sites, making distributed management even
more important. The service provider should utilize an NMS system more important. The service provider should utilize an NMS system
and standard management protocols such as SNMP [RFC1901] [RFC1902] and standard management protocols such as SNMP [RFC1901] [RFC1902]
[RFC1903] [RFC1904] [RFC1905] [RFC1906] and its associated MIBs as [RFC1903] [RFC1904] [RFC1905] [RFC1906] and its associated MIBs as
standard interfaces to configure, monitor and provision devices at standard interfaces to configure, monitor and provision devices at
E. Mannie et. al. Internet-Draft May 2002 46
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
various locations. The service provider may also wish to use the various locations. The service provider may also wish to use the
command line interface (CLI) provided by vendors with their devices, command line interface (CLI) provided by vendors with their devices,
but this however, is not a standard or recommended solution due to but this however, is not a standard or recommended solution due to
the fact that there is no standard CLI language or interface, which the fact that there is no standard CLI language or interface, which
results in N different CLIÆs in a network with devices from N results in N different CLIÆs in a network with devices from N
different vendors. In the context of GMPLS, it is extremely different vendors. In the context of GMPLS, it is extremely
important for standard interfaces to the SPÆs devices (SNMP) to important for standard interfaces to the SPÆs devices (SNMP) to
exist due to the nature of the technology itself. Since GMPLS exist due to the nature of the technology itself. Since GMPLS
comprises many different layers of control-plane and data-plane comprises many different layers of control-plane and data-plane
technology, it is important for management interfaces in this area technology, it is important for management interfaces in this area
to be flexible enough to allow the manager to manage GMPLS easily, to be flexible enough to allow the manager to manage GMPLS easily,
and in a standard way. and in a standard way.
13.1. Network Management Systems (NMS) 14.1. Network Management Systems (NMS)
The NMS system should maintain the collective information about each The NMS system should maintain the collective information about each
device within the system. Note that the NMS system may actually be device within the system. Note that the NMS system may actually be
comprised of several distributed applications (i.e.: alarm comprised of several distributed applications (i.e.: alarm
aggregators, configuration consoles, polling applications, etc...) aggregators, configuration consoles, polling applications, etc...)
that collectively comprises the SPÆs NMS. In this way, it can make that collectively comprises the SPÆs NMS. In this way, it can make
provisioning and maintenance decisions with the full knowledge of provisioning and maintenance decisions with the full knowledge of
the entire SP network. Configuration or provisioning information the entire SP network. Configuration or provisioning information
(i.e.: requests for new services) could be entered into the NMS and (i.e.: requests for new services) could be entered into the NMS and
subsequently distributed via SNMP to the remote devices, making the subsequently distributed via SNMP to the remote devices, making the
SPÆs job of managing the network much more compact and effortless SPÆs job of managing the network much more compact and effortless
E. Mannie et. al. Internet-Draft September 2002 49
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
than having to manage each device individually (i.e.: via CLI). than having to manage each device individually (i.e.: via CLI).
Security and access control can be achieved through the use of Security and access control can be achieved through the use of
SNMPv3 and the View Access Control Model [SNMPv3VACM]. This approach SNMPv3 and the View Access Control Model [SNMPv3VACM]. This approach
can be very effectively used within an SP network, since the SP has can be very effectively used within an SP network, since the SP has
access to and control over all devices within its domain. access to and control over all devices within its domain.
Standardized MIBs will need to be developed before this approach can Standardized MIBs will need to be developed before this approach can
be used ubiquitously to provision, configure and monitor devices in be used ubiquitously to provision, configure and monitor devices in
non-heterogeneous networks or across SP boundaries. non-heterogeneous networks or across SP boundaries.
13.2. Management Information Base (MIB) 14.2. Management Information Base (MIB)
In the context of GMPLS, it is extremely important for standard In the context of GMPLS, it is extremely important for standard
interfaces to devices to exist due to the nature of the technology interfaces to devices to exist due to the nature of the technology
itself. Since GMPLS comprises many different layers of control-plane itself. Since GMPLS comprises many different layers of control-plane
technology, it is important for SNMP MIBs in this area to be technology, it is important for SNMP MIBs in this area to be
flexible enough to allow the manager to manage the entire control flexible enough to allow the manager to manage the entire control
plane. This should be through a set of MIBs that may cooperate plane. This should be through a set of MIBs that may cooperate
(i.e.: coordinated row-creation on the agent), or through more (i.e.: coordinated row-creation on the agent), or through more
generalized MIBs that aggregate some of the desired actions to be generalized MIBs that aggregate some of the desired actions to be
taken and push those details down to the devices. It is important to taken and push those details down to the devices. It is important to
note that in certain circumstances, it may be necessary to duplicate note that in certain circumstances, it may be necessary to duplicate
some small subset of manageable objects in new MIBs for the some small subset of manageable objects in new MIBs for the
convenience of management. Control of some parts of GMPLS may also convenience of management. Control of some parts of GMPLS may also
be achieved though the use of existing MIB interfaces (i.e.: be achieved though the use of existing MIB interfaces (i.e.:
existing SONET MIB), or though separate ones, which are yet to be existing SONET MIB), or though separate ones, which are yet to be
defined. MIBs may have been previously defined in the IETF or ITU. defined. MIBs may have been previously defined in the IETF or ITU.
Existing MIBs may need to be extended to facilitate some of the new Existing MIBs may need to be extended to facilitate some of the new
functionality desired by GMPLS. In these cases, the working group functionality desired by GMPLS. In these cases, the working group
E. Mannie et. al. Internet-Draft May 2002 47
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
should work on new versions of these MIBs so that these extensions should work on new versions of these MIBs so that these extensions
can be added. can be added.
13.3. Tools 14.3. Tools
As in traditional networks, standard tools such as traceroute As in traditional networks, standard tools such as traceroute
[RFC1393] and ping [RFC1739] are needed for debugging and [RFC1393] and ping [RFC1739] are needed for debugging and
performance monitoring of GMPLS networks, and mainly for the control performance monitoring of GMPLS networks, and mainly for the control
plane topology that will mimic the data plane topology. Furthermore, plane topology that will mimic the data plane topology. Furthermore,
such tools provide network reachability information. The GMPLS such tools provide network reachability information. The GMPLS
control protocols will need to expose certain pieces of information control protocols will need to expose certain pieces of information
in order for these tools to function properly and to provide in order for these tools to function properly and to provide
information germane to GMPLS. These tools should be made available information germane to GMPLS. These tools should be made available
via the CLI. These tools should also be made available for remote via the CLI. These tools should also be made available for remote
invocation via the SNMP interface [RFC2925]. invocation via the SNMP interface [RFC2925].
13.4. Fault Correlation Between Multiple Layers 14.4. Fault Correlation Between Multiple Layers
Due to the nature of GMPLS and the fact that potential layers may be Due to the nature of GMPLS and the fact that potential layers may be
involved in the control and transmission of GMPLS data and control involved in the control and transmission of GMPLS data and control
information, it is therefore required that a fault in one layer be information, it is therefore required that a fault in one layer be
passed to the adjacent higher and lower layers in an effort to passed to the adjacent higher and lower layers in an effort to
notify them of the fault. However, due to nature of these many notify them of the fault. However, due to nature of these many
layers, it is possible and even probable, that hundreds or even layers, it is possible and even probable, that hundreds or even
thousands of notifications may need to transpire between layers. thousands of notifications may need to transpire between layers.
This is undesirable for several reasons. First, these notifications This is undesirable for several reasons. First, these notifications
E. Mannie et. al. Internet-Draft September 2002 50
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
will overwhelm the device. Second, if the device(s) are programmed will overwhelm the device. Second, if the device(s) are programmed
to emit SNMP Notifications [RFC1901] then the large number of to emit SNMP Notifications [RFC1901] then the large number of
notifications the device may attempt to emit may overwhelm the notifications the device may attempt to emit may overwhelm the
network with a storm of notifications. Furthermore, even if the network with a storm of notifications. Furthermore, even if the
device emits the notifications, the NMS that must process these device emits the notifications, the NMS that must process these
notifications will either be overwhelmed, or will be processing notifications will either be overwhelmed, or will be processing
redundant information. That is, if 1000 interfaces at layer B are redundant information. That is, if 1000 interfaces at layer B are
stacked above a single interface below it at layer A, and the stacked above a single interface below it at layer A, and the
interface at A goes down, the interfaces at layer B should not emit interface at A goes down, the interfaces at layer B should not emit
notifications. Instead, the interface at layer A should emit a notifications. Instead, the interface at layer A should emit a
skipping to change at line 2679 skipping to change at line 2835
notifications for the reasons described above. In the context of notifications for the reasons described above. In the context of
SNMP MIBs, all MIBs that are used by GMPLS must provide SNMP MIBs, all MIBs that are used by GMPLS must provide
enable/disable objects for all notification objects. Furthermore, enable/disable objects for all notification objects. Furthermore,
these MIBs must also provide notification summarization objects or these MIBs must also provide notification summarization objects or
functionality (as described above) as well. NMS systems and standard functionality (as described above) as well. NMS systems and standard
tools which process notifications or keep track of the many layers tools which process notifications or keep track of the many layers
on any given devices must be capable of processing the vast amount on any given devices must be capable of processing the vast amount
of information which may potentially be emitted by network devices of information which may potentially be emitted by network devices
running GMPLS at any point in time. running GMPLS at any point in time.
E. Mannie et. al. Internet-Draft May 2002 48 15. Security considerations
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
14. Security considerations
GMPLS defines a new control plane architecture for multiple types of GMPLS defines a new control plane architecture for multiple types of
network elements. In general, since LSPs established using GMPLS are network elements. In general, since LSPs established using GMPLS are
expected to carry high volumes of data and consume significant expected to carry high volumes of data and consume significant
network resources, security mechanisms are required to safeguard the network resources, security mechanisms are required to safeguard the
underlying network against attacks on the control plane and/or underlying network against attacks on the control plane and/or
unauthorized usage of data transport resources. unauthorized usage of data transport resources.
Security requirements depend on the level of trust between nodes Security requirements depend on the level of trust between nodes
that exchange GMPLS control messages as well as the exposure of the that exchange GMPLS control messages as well as the exposure of the
skipping to change at line 2710 skipping to change at line 2863
Security mechanisms can provide two main properties: authentication Security mechanisms can provide two main properties: authentication
and confidentiality. Authentication can provide origin verification, and confidentiality. Authentication can provide origin verification,
message integrity and replay protection, while confidentiality message integrity and replay protection, while confidentiality
ensures that a third party cannot decipher the contents of a ensures that a third party cannot decipher the contents of a
message. In situations where GMPLS deployment requires primarily message. In situations where GMPLS deployment requires primarily
authentication, the respective authentication mechanisms of the authentication, the respective authentication mechanisms of the
GMPLS component protocols may be used ([RFC2747], [LDP], [RFC2385], GMPLS component protocols may be used ([RFC2747], [LDP], [RFC2385],
[LMP]). Additionally, the IPSEC suite of protocols ([RFC2402], [LMP]). Additionally, the IPSEC suite of protocols ([RFC2402],
[RFC2406], [RFC2409]) may be used to provide authentication, [RFC2406], [RFC2409]) may be used to provide authentication,
confidentiality or both, for a GMPLS control channel; this option confidentiality or both, for a GMPLS control channel; this option
E. Mannie et. al. Internet-Draft September 2002 51
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
offers the benefit of combined protection of all GMPLS component offers the benefit of combined protection of all GMPLS component
protocols. protocols.
Note however that GMPLS itself introduces no new security Note however that GMPLS itself introduces no new security
considerations to the current MPLS-TE signaling (RSVP-TE, CR-LDP), considerations to the current MPLS-TE signaling (RSVP-TE, CR-LDP),
routing protocols (OSPF-TE, IS-IS-TE) or network management routing protocols (OSPF-TE, IS-IS-TE) or network management
protocols (SNMP). protocols (SNMP).
15. Acknowledgements 16. Acknowledgements
This draft is the work of numerous authors and consists of a This draft is the work of numerous authors and consists of a
composition of a number of previous drafts in this area. composition of a number of previous drafts in this area.
Many thanks to Ben Mack-Crane (Tellabs) for all the useful SDH/SONET Many thanks to Ben Mack-Crane (Tellabs) for all the useful SDH/SONET
discussions that we had together. Thanks also to Pedro Falcao, discussions that we had together. Thanks also to Pedro Falcao,
Alexandre Geyssens, Michael Moelants, Xavier Neerdaels, Philippe Alexandre Geyssens, Michael Moelants, Xavier Neerdaels, and Philippe
Noel and Fuhua Yin from Ebone for their SDH/SONET and optical Noel from Ebone for their SDH/SONET and optical technical advice and
technical advice and support. Finally, many thanks also to Krishna support. Finally, many thanks also to Krishna Mitra (Calient) and
Mitra (Calient) and Curtis Villamizar (Avici). Curtis Villamizar (Avici).
A list of the drafts from which material and ideas were incorporated A list of the drafts from which material and ideas were incorporated
follows: follows:
[GMPLS-SIG] draft-ietf-mpls-generalized-signaling-06.txt [GMPLS-SIG] draft-ietf-mpls-generalized-signaling-07.txt
Generalized MPLS - Signaling Functional Description Generalized MPLS - Signaling Functional Description
E. Mannie et. al. Internet-Draft May 2002 49 [RSVP-TE-GMPLS] draft-ietf-mpls-generalized-rsvp-te-06.txt
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
[RSVP-TE-GMPLS] draft-ietf-mpls-generalized-rsvp-te-05.txt
Generalized MPLS Signaling - RSVP-TE Extensions Generalized MPLS Signaling - RSVP-TE Extensions
[CR-LDP-GMPLS] draft-ietf-mpls-generalized-cr-ldp-04.txt [CR-LDP-GMPLS] draft-ietf-mpls-generalized-cr-ldp-05.txt
Generalized MPLS Signaling - CR-LDP Extensions Generalized MPLS Signaling - CR-LDP Extensions
[SONETSDH-GMPLS] draft-ietf-ccamp-gmpls-sonet-sdh-02.txt [SONETSDH-GMPLS] draft-ietf-ccamp-gmpls-sonet-sdh-03.txt
GMPLS Extensions for SONET and SDH Control GMPLS Extensions for SONET and SDH Control
[SONETSDH-EXT-GMPLS] draft-ietf-ccamp-gmpls-sonet-sdh-extensions- [SONETSDH-EXT-GMPLS] draft-ietf-ccamp-gmpls-sonet-sdh-extensions-
00.txt. GMPLS Extensions to Control Non-Standard 01.txt. GMPLS Extensions to Control Non-Standard
SONET and SDH Features SONET and SDH Features
[G709-GMPLS] draft-fontana-ccamp-gmpls-g709-01.txt [G709-GMPLS] draft-fontana-ccamp-gmpls-g709-01.txt
GMPLS Signaling Extensions for G.709 Optical GMPLS Signaling Extensions for G.709 Optical
Transport Networks Control Transport Networks Control
[LMP] draft-ietf-mpls-lmp-02.txt [LMP] draft-ietf-mpls-lmp-02.txt
Link Management Protocol (LMP) Link Management Protocol (LMP)
[HIERARCHY] draft-ietf-mpls-lsp-hierarchy-02.txt [LMP-WDM] draft-ietf-ccamp-lmp-wdm-00.txt
LMP for WDM Optical Line Systems (LMP-WDM)
[HIERARCHY] draft-ietf-mpls-lsp-hierarchy-04.txt
LSP Hierarchy with MPLS TE LSP Hierarchy with MPLS TE
[RSVP-TE-UNNUM] draft-ietf-mpls-rsvp-unnum-02.txt [RSVP-TE-UNNUM] draft-ietf-mpls-rsvp-unnum-04.txt
Signalling Unnumbered Links in RSVP-TE Signalling Unnumbered Links in RSVP-TE
[CR-LDP-UNNUM] draft-ietf-mpls-crldp-unnum-02.txt E. Mannie et. al. Internet-Draft September 2002 52
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
[CR-LDP-UNNUM] draft-ietf-mpls-crldp-unnum-04.txt
Signalling Unnumbered Links in CR-LDP Signalling Unnumbered Links in CR-LDP
[BUNDLE] draft-ietf-mpls-bundle-00.txt [BUNDLE] draft-ietf-mpls-bundle-01.txt
Link Bundling in MPLS Traffic Engineering Link Bundling in MPLS Traffic Engineering
[GMPLS-ROUTING] draft-ietf-ccamp-gmpls-routing-00.txt [GMPLS-ROUTING] draft-ietf-ccamp-gmpls-routing-02.txt
Routing Extensions in Support of Generalized MPLS Routing Extensions in Support of Generalized MPLS
[OSPF-TE-GMPLS] draft-ietf-ccamp-ospf-gmpls-extensions-00.txt [OSPF-TE-GMPLS] draft-ietf-ccamp-ospf-gmpls-extensions-04.txt
OSPF Extensions in Support of Generalized MPLS OSPF Extensions in Support of Generalized MPLS
[ISIS-TE-GMPLS] draft-ietf-isis-gmpls-extensions-04.txt [ISIS-TE-GMPLS] draft-ietf-isis-gmpls-extensions-08.txt
IS-IS Extensions in Support of Generalized MPLS IS-IS Extensions in Support of Generalized MPLS
16. References 17. References
[RFC1393] G. Malkin, "Traceroute Using an IP Option", IETF [RFC1393] G. Malkin, "Traceroute Using an IP Option", IETF
RFC 1393, January 1993. RFC 1393, January 1993.
[RFC1901] Case, J., McCloghrie, K., Rose, M., and S. [RFC1901] Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Introduction to Community-based Waldbusser, "Introduction to Community-based
SNMPv2", IETF RFC 1901, January 1996. SNMPv2", IETF RFC 1901, January 1996.
[RFC1902] Case, J., McCloghrie, K., Rose, M., and S. [RFC1902] Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Structure of Management Information for Waldbusser, "Structure of Management Information for
Version 2 of the Simple Network Management Protocol Version 2 of the Simple Network Management Protocol
(SNMPv2)", IETF RFC 1901, January 1996. (SNMPv2)", IETF RFC 1901, January 1996.
E. Mannie et. al. Internet-Draft May 2002 50
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
[RFC1903] Case, J., McCloghrie, K., Rose, M., and S. [RFC1903] Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Textual Conventions for Version 2 of the Waldbusser, "Textual Conventions for Version 2 of the
Simple Network Management Protocol (SNMPv2)", Simple Network Management Protocol (SNMPv2)",
IETF RFC 1901, January 1996. IETF RFC 1901, January 1996.
[RFC1904] Case, J., McCloghrie, K., Rose, M., and S. [RFC1904] Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Conformance Statements for Version 2 of Waldbusser, "Conformance Statements for Version 2 of
the Simple Network Management Protocol (SNMPv2)", the Simple Network Management Protocol (SNMPv2)",
IETF RFC 1901, January 1996. IETF RFC 1901, January 1996.
skipping to change at line 2822 skipping to change at line 2979
[RFC1906] Case, J., McCloghrie, K., Rose, M., and S. [RFC1906] Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Transport Mappings for Version 2 of Waldbusser, "Transport Mappings for Version 2 of
the Simple Network Management Protocol (SNMPv2)", the Simple Network Management Protocol (SNMPv2)",
IETF RFC 1906, January 1996. IETF RFC 1906, January 1996.
[SNMPv3VACM] Wijnen, B., Presuhn, R., and K. McCloghrie, "View- [SNMPv3VACM] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-
based Access Control Model (VACM) for the Simple based Access Control Model (VACM) for the Simple
Network Management Protocol (SNMP)", IETF RFC 2575, Network Management Protocol (SNMP)", IETF RFC 2575,
April 1999. April 1999.
E. Mannie et. al. Internet-Draft September 2002 53
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
[RFC1739] G. Kessler, S. Shepard , "A Primer On Internet and [RFC1739] G. Kessler, S. Shepard , "A Primer On Internet and
TCP/IP Tools", RFC1739, December 1994. TCP/IP Tools", RFC1739, December 1994.
[RFC2328] J. Moy, "OSPF Version 2", RFC 2328, Standard [RFC2328] J. Moy, "OSPF Version 2", RFC 2328, Standard
Track, April 1998. Track, April 1998.
[RFC2370] R. Coltun, "The OSPF Opaque LSA Option", RFC 2370 [RFC2370] R. Coltun, "The OSPF Opaque LSA Option", RFC 2370
Standard Track, July 1998. Standard Track, July 1998.
[RFC2385] A. Heffernan, "Protection of BGP Sessions via the TCP [RFC2385] A. Heffernan, "Protection of BGP Sessions via the TCP
skipping to change at line 2850 skipping to change at line 3010
[RFC2409] D. Harkins and D. Carrel, "The Internet Key Exchange [RFC2409] D. Harkins and D. Carrel, "The Internet Key Exchange
(IKE)", IETF RFC 2409. (IKE)", IETF RFC 2409.
[RFC2747] F. Baker et al., "RSVP Cryptographic Authentication", [RFC2747] F. Baker et al., "RSVP Cryptographic Authentication",
IETF RFC 2747. IETF RFC 2747.
[RFC2925] K. White, "Definitions of Managed Objects for Remote [RFC2925] K. White, "Definitions of Managed Objects for Remote
Ping, Traceroute, and Lookup Operations", IETF RFC Ping, Traceroute, and Lookup Operations", IETF RFC
2925, September 2000. 2925, September 2000.
E. Mannie et. al. Internet-Draft May 2002 51
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
[RFC3031] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol [RFC3031] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol
Label Switching Architecture", IETF RFC 3031, January Label Switching Architecture", IETF RFC 3031, January
2001. 2001.
[RFC3032] E. Rosen, D. Tappan, G. Fedorkow, Y. Rekhter, D. [RFC3032] E. Rosen, D. Tappan, G. Fedorkow, Y. Rekhter, D.
Farinacci, T. Li, A. Conta, " MPLS Label Stack Farinacci, T. Li, A. Conta, " MPLS Label Stack
Encoding", IETF RFC 3032, January 2001. Encoding", IETF RFC 3032, January 2001.
[LPD] L. Andersson, P. Doolan, N. Feldman, A. Fredette, [LPD] L. Andersson, P. Doolan, N. Feldman, A. Fredette,
B. Thomas, "LDP Specification", IETF RFC 3036, January B. Thomas, "LDP Specification", IETF RFC 3036, January
2001. 2001.
[OSPF-TE] D. Katz, D. Yeung, and K. Kompella, "Traffic [OSPF-TE] D. Katz, D. Yeung, and K. Kompella, "Traffic
Engineering Extensions to OSPF", draft-katz-yeung-ospf- Engineering Extensions to OSPF", draft-katz-yeung-ospf-
traffic-05.txt. traffic-05.txt.
[LMP-WDM] A. Fredette et al., "Link Management Protocol (LMP) for
WDM Transmission Systems," Internet Draft, Work in
Progress, draft-fredette-lmp-wdm-01.txt, March 2001.
[MPLS-TEO] D. Awduche et al., "Multi-Protocol Lambda Switching: [MPLS-TEO] D. Awduche et al., "Multi-Protocol Lambda Switching:
Combining MPLS Traffic Engineering Control With Optical Combining MPLS Traffic Engineering Control With Optical
Crossconnects," Internet Draft, Work in Progress, Crossconnects," Internet Draft, Work in Progress,
draft-awduche-mpls-te-optical-03.txt, April 2001. draft-awduche-mpls-te-optical-03.txt, April 2001.
[G.841] ITU-T Recommendation G.841, "Types and Characteristics [G.841] ITU-T Recommendation G.841, "Types and Characteristics
of SDH Network Protection Architectures," July 1995. of SDH Network Protection Architectures," July 1995.
E. Mannie et. al. Internet-Draft September 2002 54
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
[ANSI-T1.105] "Synchronous Optical Network (SONET): Basic [ANSI-T1.105] "Synchronous Optical Network (SONET): Basic
Description Including Multiplex Structure, Rates, and Description Including Multiplex Structure, Rates, and
Formats" ANSI T1.105, 2000. Formats" ANSI T1.105, 2000.
[TE-RESTORE] W. Lai, D. McDysan, J. Boyle, et al, "Network Hierarchy [TE-RESTORE] W. Lai, D. McDysan, J. Boyle, et al, "Network Hierarchy
and Multi-layer Survivability", Internet Draft, Work in and Multi-layer Survivability", Internet Draft, Work in
Progress, draft-team-tewg-restore-hierarchy-00.txt, Progress, draft-team-tewg-restore-hierarchy-00.txt,
July 2001. July 2001.
[MPLS-RECOVERY] V. Sharma and F. Hellstrand (Editors), "A Framework [MPLS-RECOVERY] V. Sharma and F. Hellstrand (Editors), "A Framework
for MPLS Recovery", Internet Draft, Work in Progress, for MPLS Recovery", Internet Draft, Work in Progress,
draft-ietf-mpls-recovery-frmwrk-03.txt, July 2001. draft-ietf-mpls-recovery-frmwrk-03.txt, July 2001.
[SDH/SONET-GMPLS-FRAMEWORK] G. Bernstein, E. Mannie, V. Sharma,
"Framework for GMPLS-based Control of SDH/SONET
Networks", Internet Draft, Work in Progress,
draft-ccamp-optical-sdhsonet-mpls-control-frmwrk-
00.txt, February 2002.
[OLI-REQ] A. Fredette (Editor), "Optical Link Interface
Requirements", Internet Draft, Work in Progress,
draft-ietf-ccamp-oli-reqts-00.txt, February 2002.
[MANCHESTER] J. Manchester, P. Bonenfant, C. Newton, "The Evolution [MANCHESTER] J. Manchester, P. Bonenfant, C. Newton, "The Evolution
of Transport Network Survivability," IEEE of Transport Network Survivability," IEEE
Communications, August 1999. Communications, August 1999.
E. Mannie et. al. Internet-Draft May 2002 52 18. Author's Addresses
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
17. Author's Addresses
Peter Ashwood-Smith Eric Mannie (editor) Peter Ashwood-Smith Eric Mannie (editor)
Nortel Networks Corp. Ebone (GTS) Nortel Networks Corp. Ebone (GTS)
P.O. Box 3511 Station C, Terhulpsesteenweg 6A P.O. Box 3511 Station C, Terhulpsesteenweg 6A
Ottawa, ON K1Y 4H7 1560 Hoeilaart Ottawa, ON K1Y 4H7 1560 Hoeilaart
Canada Belgium Canada Belgium
Phone: +1 613 763 4534 Phone: +32 2 658 56 52 Phone: +1 613 763 4534 Phone: +32 2 658 56 52
Email: Email: eric.mannie@gts.com Email: Email: eric.mannie@gts.com
petera@nortelnetworks.com petera@nortelnetworks.com
Daniel O. Awduche Thomas D. Nadeau Daniel O. Awduche Thomas D. Nadeau
Movaz Networks Cisco Systems, Inc. Movaz Networks Cisco Systems, Inc.
7296 Jones Branch Drive 250 Apollo Drive 7296 Jones Branch Drive 250 Apollo Drive
Suite 615 Chelmsford, MA 01824 Suite 615 Chelmsford, MA 01824
McLean, VA 22102 USA McLean, VA 22102 USA
USA Phone: +1 978 244 3051 USA Phone: +1 978 244 3051
Phone: +1 703 847-7350 Email: tnadeau@cisco.com Phone: +1 703 847-7350 Email: tnadeau@cisco.com
Email: awduche@movaz.com Email: awduche@movaz.com
E. Mannie et. al. Internet-Draft September 2002 55
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
Ayan Banerjee Lyndon Ong Ayan Banerjee Lyndon Ong
Calient Networks Ciena Systems Calient Networks Ciena Systems
5853 Rue Ferrari 10480 Ridgeview Ct 5853 Rue Ferrari 10480 Ridgeview Ct
San Jose, CA 95138 Cupertino, CA 95014 San Jose, CA 95138 Cupertino, CA 95014
USA USA USA USA
Phone: +1 408 972-3645 Email: lyong@ciena.com Phone: +1 408 972-3645 Email: lyong@ciena.com
Email: abanerjee@calient.net Email: abanerjee@calient.net
Debashis Basak Dimitri Papadimitriou Debashis Basak Dimitri Papadimitriou
Accelight Networks Alcatel - IPO NSG Accelight Networks Alcatel - IPO NSG
skipping to change at line 2947 skipping to change at line 3113
Lou Berger Dimitrios Pendarakis Lou Berger Dimitrios Pendarakis
Movaz Networks, Inc. Tellium, Inc. Movaz Networks, Inc. Tellium, Inc.
7926 Jones Branch Drive 2 Crescent Place 7926 Jones Branch Drive 2 Crescent Place
Suite 615 P.O. Box 901 Suite 615 P.O. Box 901
MCLean VA, 22102 Oceanport, NJ 07757-0901 MCLean VA, 22102 Oceanport, NJ 07757-0901
USA USA USA USA
Phone: +1 703 847-1801 Email: DPendarakis@tellium.com Phone: +1 703 847-1801 Email: DPendarakis@tellium.com
Email: lberger@movaz.com Email: lberger@movaz.com
E. Mannie et. al. Internet-Draft May 2002 53
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
Greg Bernstein Bala Rajagopalan Greg Bernstein Bala Rajagopalan
Ciena Corporation Tellium, Inc. Ciena Corporation Tellium, Inc.
10480 Ridgeview Court 2 Crescent Place 10480 Ridgeview Court 2 Crescent Place
Cupertino, CA 94014 P.O. Box 901 Cupertino, CA 94014 P.O. Box 901
USA Oceanport, NJ 07757-0901 USA Oceanport, NJ 07757-0901
Phone: +1 408 366 4713 USA Phone: +1 408 366 4713 USA
Email: greg@ciena.com Phone: +1 732 923 4237 Email: greg@ciena.com Phone: +1 732 923 4237
Email: braja@tellium.com Email: braja@tellium.com
Sudheer Dharanikota Yakov Rekhter Sudheer Dharanikota Yakov Rekhter
skipping to change at line 2974 skipping to change at line 3137
Email: sudheer@nayna.com Email: sudheer@nayna.com
John Drake Debanjan Saha John Drake Debanjan Saha
Calient Networks Tellium Optical Systems Calient Networks Tellium Optical Systems
5853 Rue Ferrari 2 Crescent Place 5853 Rue Ferrari 2 Crescent Place
San Jose, CA 95138 Oceanport, NJ 07757-0901 San Jose, CA 95138 Oceanport, NJ 07757-0901
USA USA USA USA
Phone: +1 408 972 3720 Phone: +1 732 923 4264 Phone: +1 408 972 3720 Phone: +1 732 923 4264
Email: jdrake@calient.net Email: dsaha@tellium.com Email: jdrake@calient.net Email: dsaha@tellium.com
E. Mannie et. al. Internet-Draft September 2002 56
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
Yanhe Fan Hal Sandick Yanhe Fan Hal Sandick
Axiowave Networks, Inc. Nortel Networks Axiowave Networks, Inc. Nortel Networks
200 Nickerson Road Email: 200 Nickerson Road Email:
Marlborough, MA 01752 hsandick@nortelnetworks.com Marlborough, MA 01752 hsandick@nortelnetworks.com
USA USA
Phone: +1 774 348 4627 Phone: +1 774 348 4627
Email: yfan@axiowave.com Email: yfan@axiowave.com
Don Fedyk Vishal Sharma Don Fedyk Vishal Sharma
Nortel Networks Corp. Metanoia, Inc. Nortel Networks Corp. Metanoia, Inc.
skipping to change at line 2999 skipping to change at line 3165
dwfedyk@nortelnetworks.com Email: vsharma87@yahoo.com dwfedyk@nortelnetworks.com Email: vsharma87@yahoo.com
Gert Grammel George Swallow Gert Grammel George Swallow
Alcatel Cisco Systems, Inc. Alcatel Cisco Systems, Inc.
Via Trento, 30 250 Apollo Drive Via Trento, 30 250 Apollo Drive
20059 Vimercate (Mi) Chelmsford, MA 01824 20059 Vimercate (Mi) Chelmsford, MA 01824
Italy USA Italy USA
Email: gert.grammel@alcatel.it Phone: +1 978 244 8143 Email: gert.grammel@alcatel.it Phone: +1 978 244 8143
Email: swallow@cisco.com Email: swallow@cisco.com
E. Mannie et. al. Internet-Draft May 2002 54
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
Dan Guo Z. Bo Tang Dan Guo Z. Bo Tang
Turin Networks, Inc. Tellium, Inc. Turin Networks, Inc. Tellium, Inc.
1415 N. McDowell Blvd, 2 Crescent Place 1415 N. McDowell Blvd, 2 Crescent Place
Petaluma, CA 95454 P.O. Box 901 Petaluma, CA 95454 P.O. Box 901
USA Oceanport, NJ 07757-0901 USA Oceanport, NJ 07757-0901
Email: dguo@turinnetworks.com USA Email: dguo@turinnetworks.com USA
Phone: +1 732 923 4231 Phone: +1 732 923 4231
Email: btang@tellium.com Email: btang@tellium.com
Kireeti Kompella Jennifer Yates Kireeti Kompella Jennifer Yates
skipping to change at line 3026 skipping to change at line 3189
Email: kireeti@juniper.net Email: jyates@research.att.com Email: kireeti@juniper.net Email: jyates@research.att.com
Alan Kullberg George R. Young Alan Kullberg George R. Young
NetPlane Systems, Inc. Edgeflow NetPlane Systems, Inc. Edgeflow
888 Washington 329 March Road 888 Washington 329 March Road
St.Dedham, MA 02026 Ottawa, Ontario, K2K 2E1 St.Dedham, MA 02026 Ottawa, Ontario, K2K 2E1
USA Canada USA Canada
Phone: +1 781 251-5319 Email: Phone: +1 781 251-5319 Email:
Email: akullber@netplane.com george.young@edgeflow.com Email: akullber@netplane.com george.young@edgeflow.com
E. Mannie et. al. Internet-Draft September 2002 57
draft-ietf-ccamp-gmpls-architecture-02.txt March 2002
Jonathan P. Lang John Yu Jonathan P. Lang John Yu
Calient Networks Zaffire Inc. Calient Networks Zaffire Inc.
25 Castilian 2630 Orchard Parkway 25 Castilian 2630 Orchard Parkway
Goleta, CA 93117 San Jose, CA 95134 Goleta, CA 93117 San Jose, CA 95134
Email: jplang@calient.net USA Email: jplang@calient.net USA
Email: jzyu@zaffire.com Email: jzyu@zaffire.com
Fong Liaw Alex Zinin Fong Liaw Alex Zinin
Zaffire Inc. Cisco Systems Zaffire Inc. Nexsi Systems
2630 Orchard Parkway 150 W. Tasman Dr. 2630 Orchard Parkway 178 East Tasman Dr
San Jose, CA 95134 San Jose, CA 95134 San Jose, CA 95134 San Jose, CA 95134
USA Email: azinin@cisco.com USA USA
Email: fliaw@zaffire.com Email: fliaw@zaffire.com
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E. Mannie et. al. Internet-Draft May 2002 55
draft-ietf-ccamp-gmpls-architecture-01.txt November 2001
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E. Mannie et. al. Internet-Draft May 2002 56 E. Mannie et. al. Internet-Draft September 2002 58
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