draft-ietf-idr-ls-distribution-00.txt   draft-ietf-idr-ls-distribution-01.txt 
Inter-Domain Routing H. Gredler Inter-Domain Routing H. Gredler
Internet-Draft Juniper Networks, Inc. Internet-Draft Juniper Networks, Inc.
Intended status: Standards Track J. Medved Intended status: Standards Track J. Medved
Expires: March 21, 2013 S. Previdi Expires: April 25, 2013 S. Previdi
Cisco Systems, Inc. Cisco Systems, Inc.
A. Farrel A. Farrel
Juniper Networks, Inc. Juniper Networks, Inc.
September 19, 2012 S. Ray
Cisco Systems, Inc.
October 22, 2012
North-Bound Distribution of Link-State and TE Information using BGP North-Bound Distribution of Link-State and TE Information using BGP
draft-ietf-idr-ls-distribution-00 draft-ietf-idr-ls-distribution-01
Abstract Abstract
In a number of environments, a component external to a network is In a number of environments, a component external to a network is
called upon to perform computations based on the network topology and called upon to perform computations based on the network topology and
current state of the connections within the network, including current state of the connections within the network, including
traffic engineering information. This is information typically traffic engineering information. This is information typically
distributed by IGP routing protocols within the network distributed by IGP routing protocols within the network
This document describes a mechanism by which links state and traffic This document describes a mechanism by which links state and traffic
skipping to change at page 2, line 4 skipping to change at page 1, line 39
(NLRI) encoding format. The mechanism is applicable to physical and (NLRI) encoding format. The mechanism is applicable to physical and
virtual links. The mechanism described is subject to policy control. virtual links. The mechanism described is subject to policy control.
Applications of this technique include Application Layer Traffic Applications of this technique include Application Layer Traffic
Optimization (ALTO) servers, and Path Computation Elements (PCEs). Optimization (ALTO) servers, and Path Computation Elements (PCEs).
Requirements Language Requirements Language
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 this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119] document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 21, 2013. This Internet-Draft will expire on April 25, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Motivation and Applicability . . . . . . . . . . . . . . . . . 5 2. Motivation and Applicability . . . . . . . . . . . . . . . . . 5
2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 5 2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 5
2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 6 2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 7
3. Carrying Link State Information in BGP . . . . . . . . . . . . 7 3. Carrying Link State Information in BGP . . . . . . . . . . . . 8
3.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. The Link State NLRI . . . . . . . . . . . . . . . . . . . 8 3.2. The Link State NLRI . . . . . . . . . . . . . . . . . . . 9
3.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . . 10 3.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . . 11
3.2.1.1. Local Node Descriptors . . . . . . . . . . . . . . 11 3.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . . 15
3.2.1.2. Remote Node Descriptors . . . . . . . . . . . . . 11 3.2.3. The Prefix NLRI . . . . . . . . . . . . . . . . . . . 16
3.2.1.3. Node Descriptor Sub-TLVs . . . . . . . . . . . . . 12 3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 16
3.2.1.4. Router-ID Anchoring Example: ISO Pseudonode . . . 12 3.3.1. Link Attribute TLVs . . . . . . . . . . . . . . . . . 16
3.2.1.5. Router-ID Anchoring Example: OSPFv2 to IS-IS 3.3.2. Node Attribute TLVs . . . . . . . . . . . . . . . . . 20
Migration . . . . . . . . . . . . . . . . . . . . 13 3.3.3. Prefix Attributes TLVs . . . . . . . . . . . . . . . . 23
3.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . . 13 3.4. BGP Next Hop Information . . . . . . . . . . . . . . . . . 27
3.2.2.1. Multi Topology ID TLV . . . . . . . . . . . . . . 14 3.5. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 27
3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 14 4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 27
3.3.1. Link Attribute TLVs . . . . . . . . . . . . . . . . . 14 4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 27
3.3.1.1. MPLS Protocol Mask TLV . . . . . . . . . . . . . . 15 4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 28
3.3.1.2. Metric TLV . . . . . . . . . . . . . . . . . . . . 16 4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 28
3.3.1.3. Shared Risk Link Group TLV . . . . . . . . . . . . 16 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
3.3.1.4. OSPF Specific Link Attribute TLV . . . . . . . . . 17 6. Manageability Considerations . . . . . . . . . . . . . . . . . 29
3.3.1.5. IS-IS specific link attribute TLV . . . . . . . . 17 6.1. Operational Considerations . . . . . . . . . . . . . . . . 29
3.3.1.6. Link Area TLV . . . . . . . . . . . . . . . . . . 18 6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 29
3.3.2. Node Attribute TLVs . . . . . . . . . . . . . . . . . 18 6.1.2. Installation and Initial Setup . . . . . . . . . . . . 30
3.3.2.1. Multi Topology Node TLV . . . . . . . . . . . . . 18 6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 30
3.3.2.2. Node Flag Bits TLV . . . . . . . . . . . . . . . . 19
3.3.2.3. OSPF Specific Node Properties TLV . . . . . . . . 19
3.3.2.4. IS-IS Specific Node Properties TLV . . . . . . . . 20
3.3.2.5. Area Node TLV . . . . . . . . . . . . . . . . . . 20
3.4. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 21
4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 21
4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 21
4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 22
4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 22
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
6. Manageability Considerations . . . . . . . . . . . . . . . . . 23
6.1. Operational Considerations . . . . . . . . . . . . . . . . 23
6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 23
6.1.2. Installation and Initial Setup . . . . . . . . . . . . 23
6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 23
6.1.4. Requirements on Other Protocols and Functional 6.1.4. Requirements on Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . . 24 Components . . . . . . . . . . . . . . . . . . . . . . 30
6.1.5. Impact on Network Operation . . . . . . . . . . . . . 24 6.1.5. Impact on Network Operation . . . . . . . . . . . . . 30
6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 24 6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 30
6.2. Management Considerations . . . . . . . . . . . . . . . . 24 6.2. Management Considerations . . . . . . . . . . . . . . . . 31
6.2.1. Management Information . . . . . . . . . . . . . . . . 24 6.2.1. Management Information . . . . . . . . . . . . . . . . 31
6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 24 6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 31
6.2.3. Configuration Management . . . . . . . . . . . . . . . 24 6.2.3. Configuration Management . . . . . . . . . . . . . . . 31
6.2.4. Accounting Management . . . . . . . . . . . . . . . . 24 6.2.4. Accounting Management . . . . . . . . . . . . . . . . 31
6.2.5. Performance Management . . . . . . . . . . . . . . . . 25 6.2.5. Performance Management . . . . . . . . . . . . . . . . 31
6.2.6. Security Management . . . . . . . . . . . . . . . . . 25 6.2.6. Security Management . . . . . . . . . . . . . . . . . 32
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 32
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.1. Normative References . . . . . . . . . . . . . . . . . . . 25 9.1. Normative References . . . . . . . . . . . . . . . . . . . 32
9.2. Informative References . . . . . . . . . . . . . . . . . . 26 9.2. Informative References . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction 1. Introduction
The contents of a Link State Database (LSDB) or a Traffic Engineering The contents of a Link State Database (LSDB) or a Traffic Engineering
Database (TED) has the scope of an IGP area. Some applications, such Database (TED) has the scope of an IGP area. Some applications, such
as end-to-end Traffic Engineering (TE), would benefit from visibility as end-to-end Traffic Engineering (TE), would benefit from visibility
outside one area or Autonomous System (AS) in order to make better outside one area or Autonomous System (AS) in order to make better
decisions. decisions.
The IETF has defined the Path Computation Element (PCE) [RFC4655] as The IETF has defined the Path Computation Element (PCE) [RFC4655] as
skipping to change at page 4, line 21 skipping to change at page 4, line 36
components using the BGP routing protocol [RFC4271]. This is components using the BGP routing protocol [RFC4271]. This is
achieved using a new BGP Network Layer Reachability Information achieved using a new BGP Network Layer Reachability Information
(NLRI) encoding format. The mechanism is applicable to physical and (NLRI) encoding format. The mechanism is applicable to physical and
virtual links. The mechanism described is subject to policy control. virtual links. The mechanism described is subject to policy control.
A router maintains one or more databases for storing link-state A router maintains one or more databases for storing link-state
information about nodes and links in any given area. Link attributes information about nodes and links in any given area. Link attributes
stored in these databases include: local/remote IP addresses, local/ stored in these databases include: local/remote IP addresses, local/
remote interface identifiers, link metric and TE metric, link remote interface identifiers, link metric and TE metric, link
bandwidth, reservable bandwidth, per CoS class reservation state, bandwidth, reservable bandwidth, per CoS class reservation state,
preemption and Shared Risk Link Groups (SRLG). The router's BGP preemption and Shared Risk Link Groups (SRLG). The router's BGP
process can retrieve topology from these LSDBs and distribute it to a process can retrieve topology from these LSDBs and distribute it to a
consumer, either directly or via a peer BGP Speaker (typically a consumer, either directly or via a peer BGP Speaker (typically a
dedicated Route Reflector), using the encoding specified in this dedicated Route Reflector), using the encoding specified in this
document. document.
The collection of Link State and TE link state information and its The collection of Link State and TE link state information and its
distribution to consumers is shown in the following figure. distribution to consumers is shown in the following figure.
+-----------+ +-----------+
| Consumer | | Consumer |
+-----------+ +-----------+
^ ^
| |
+-----------+ +-----------+
| BGP | +-----------+ | BGP | +-----------+
| Speaker | | Consumer | | Speaker | | Consumer |
+-----------+ +-----------+ +-----------+ +-----------+
^ ^ ^ ^ ^ ^ ^ ^
| | | | | | | |
+---------------+ | +-------------------+ | +---------------+ | +-------------------+ |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+
| BGP | | BGP | | BGP | | BGP | | BGP | | BGP |
| Speaker | | Speaker | . . . | Speaker | | Speaker | | Speaker | . . . | Speaker |
+-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+
^ ^ ^ ^ ^ ^
| | | | | |
IGP IGP IGP IGP IGP IGP
Figure 1: TE Link State info collection Figure 1: TE Link State info collection
A BGP Speaker may apply configurable policy to the information that A BGP Speaker may apply configurable policy to the information that
it distributes. Thus, it may distribute the real physical topology it distributes. Thus, it may distribute the real physical topology
from the LSDB or the TED. Alternatively, it may create an abstracted from the LSDB or the TED. Alternatively, it may create an abstracted
topology, where virtual, aggregated nodes are connected by virtual topology, where virtual, aggregated nodes are connected by virtual
paths. Aggregated nodes can be created, for example, out of multiple paths. Aggregated nodes can be created, for example, out of multiple
routers in a POP. Abstracted topology can also be a mix of physical routers in a POP. Abstracted topology can also be a mix of physical
and virtual nodes and physical and virtual links. Furthermore, the and virtual nodes and physical and virtual links. Furthermore, the
BGP Speaker can apply policy to determine when information is updated BGP Speaker can apply policy to determine when information is updated
to the consumer so that there is reduction of information flow form to the consumer so that there is reduction of information flow form
skipping to change at page 5, line 49 skipping to change at page 6, line 25
need to segment their core networks into distinct areas, but which need to segment their core networks into distinct areas, but which
still want to take advantage of MPLS-TE. still want to take advantage of MPLS-TE.
Previous solutions used per-domain path computation [RFC5152]. The Previous solutions used per-domain path computation [RFC5152]. The
source router could only compute the path for the first area because source router could only compute the path for the first area because
the router only has full topological visibility for the first area the router only has full topological visibility for the first area
along the path, but not for subsequent areas. Per-domain path along the path, but not for subsequent areas. Per-domain path
computation uses a technique called "loose-hop-expansion" [RFC3209], computation uses a technique called "loose-hop-expansion" [RFC3209],
and selects the exit ABR and other ABRs or AS Border Routers (ASBRs) and selects the exit ABR and other ABRs or AS Border Routers (ASBRs)
using the IGP computed shortest path topology for the remainder of using the IGP computed shortest path topology for the remainder of
the path. This may lead to sub-optimal paths, makes alternate/back- the path. This may lead to sub-optimal paths, makes alternate/
up path computation hard, and might result in no TE path being found back-up path computation hard, and might result in no TE path being
when one really does exist. found when one really does exist.
The PCE presents a computation server that may have visibility into The PCE presents a computation server that may have visibility into
more than one IGP area or AS, or may cooperate with other PCEs to more than one IGP area or AS, or may cooperate with other PCEs to
perform distributed path computation. The PCE obviously needs access perform distributed path computation. The PCE obviously needs access
to the TED for the area(s) it serves, but [RFC4655] does not describe to the TED for the area(s) it serves, but [RFC4655] does not describe
how this is achieved. Many implementations make the PCE a passive how this is achieved. Many implementations make the PCE a passive
participant in the IGP so that it can learn the latest state of the participant in the IGP so that it can learn the latest state of the
network, but this may be sub-optimal when the network is subject to a network, but this may be sub-optimal when the network is subject to a
high degree of churn, or when the PCE is responsible for multiple high degree of churn, or when the PCE is responsible for multiple
areas. areas.
The following figure shows how a PCE can get its TED information The following figure shows how a PCE can get its TED information
using the mechanism described in this document. using the mechanism described in this document.
+----------+ +---------+ +----------+ +---------+
| ----- | | BGP | | ----- | | BGP |
| | TED |<-+-------------------------->| Speaker | | | TED |<-+-------------------------->| Speaker |
| ----- | TED synchronization | | | ----- | TED synchronization | |
| | | mechanism: +---------+ | | | mechanism: +---------+
| | | BGP with Link-State NLRI | | | BGP with Link-State NLRI
| v | | v |
| ----- | | ----- |
| | PCE | | | | PCE | |
| ----- | | ----- |
+----------+ +----------+
^ ^
| Request/ | Request/
| Response | Response
v v
Service +----------+ Signaling +----------+ Service +----------+ Signaling +----------+
Request | Head-End | Protocol | Adjacent | Request | Head-End | Protocol | Adjacent |
-------->| Node |<------------>| Node | -------->| Node |<------------>| Node |
+----------+ +----------+ +----------+ +----------+
Figure 2: External PCE node using a TED synchronization mechanism Figure 2: External PCE node using a TED synchronization mechanism
The mechanism in this document allows the necessary TED information The mechanism in this document allows the necessary TED information
to be collected from the IGP within the network, filtered according to be collected from the IGP within the network, filtered according
to configurable policy, and distributed to the PCE as necessary. to configurable policy, and distributed to the PCE as necessary.
2.2. ALTO Server Network API 2.2. ALTO Server Network API
An ALTO Server [RFC5693] is an entity that generates an abstracted An ALTO Server [RFC5693] is an entity that generates an abstracted
network topology and provides it to network-aware applications over a network topology and provides it to network-aware applications over a
web service based API. Example applications are p2p clients or web service based API. Example applications are p2p clients or
trackers, or CDNs. The abstracted network topology comes in the form trackers, or CDNs. The abstracted network topology comes in the form
of two maps: a Network Map that specifies allocation of prefixes to of two maps: a Network Map that specifies allocation of prefixes to
PIDs, and a Cost Map that specifies the cost between PIDs listed in PIDs, and a Cost Map that specifies the cost between PIDs listed in
the Network Map. For more details, see [I-D.ietf-alto-protocol]. the Network Map. For more details, see [I-D.ietf-alto-protocol].
ALTO abstract network topologies can be auto-generated from the ALTO abstract network topologies can be auto-generated from the
physical topology of the underlying network. The generation would physical topology of the underlying network. The generation would
typically be based on policies and rules set by the operator. Both typically be based on policies and rules set by the operator. Both
prefix and TE data are required: prefix data is required to generate prefix and TE data are required: prefix data is required to generate
ALTO Network Maps, TE (topology) data is required to generate ALTO ALTO Network Maps, TE (topology) data is required to generate ALTO
Cost Maps. Prefix data is carried and originated in BGP, TE data is Cost Maps. Prefix data is carried and originated in BGP, TE data is
originated and carried in an IGP. The mechanism defined in this originated and carried in an IGP. The mechanism defined in this
document provides a single interface through which an ALTO Server can document provides a single interface through which an ALTO Server can
retrieve all the necessary prefix and network topology data from the retrieve all the necessary prefix and network topology data from the
underlying network. Note an ALTO Server can use other mechanisms to underlying network. Note an ALTO Server can use other mechanisms to
get network data, for example, peering with multiple IGP and BGP get network data, for example, peering with multiple IGP and BGP
Speakers. Speakers.
The following figure shows how an ALTO Server can get network The following figure shows how an ALTO Server can get network
topology information from the underlying network using the mechanism topology information from the underlying network using the mechanism
described in this document. described in this document.
+--------+ +--------+
| Client |<--+ | Client |<--+
+--------+ | +--------+ |
| ALTO +--------+ BGP with +---------+ | ALTO +--------+ BGP with +---------+
+--------+ | Protocol | ALTO | Link-State NLRI | BGP | +--------+ | Protocol | ALTO | Link-State NLRI | BGP |
| Client |<--+------------| Server |<----------------| Speaker | | Client |<--+------------| Server |<----------------| Speaker |
+--------+ | | | | | +--------+ | | | | |
| +--------+ +---------+ | +--------+ +---------+
+--------+ | +--------+ |
| Client |<--+ | Client |<--+
+--------+ +--------+
Figure 3: ALTO Server using network topology information Figure 3: ALTO Server using network topology information
3. Carrying Link State Information in BGP 3. Carrying Link State Information in BGP
Two parts: a new BGP NLRI that describes links and nodes comprising Two parts: a new BGP NLRI that describes links and nodes comprising
IGP link state information, and a new BGP path attribute that carries IGP link state information, and a new BGP path attribute that carries
link and node properties and attributes, such as the link metric or link and node properties and attributes, such as the link metric or
node properties. node properties.
3.1. TLV Format 3.1. TLV Format
Information in the new link state NLRIs and attributes is encoded in Information in the new link state NLRIs and attributes is encoded in
Type/Length/Value triplets. The TLV format is shown in Figure 4. Type/Length/Value triplets. The TLV format is shown in Figure 4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Value (variable) | | Value (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: TLV format Figure 4: TLV format
The Length field defines the length of the value portion in octets The Length field defines the length of the value portion in octets
(thus a TLV with no value portion would have a length of zero). The (thus a TLV with no value portion would have a length of zero). The
TLV is not padded to four-octet alignment; Unrecognized types are TLV is not padded to four-octet alignment; Unrecognized types are
ignored. ignored.
3.2. The Link State NLRI 3.2. The Link State NLRI
The MP_REACH and MP_UNREACH attributes are BGP's containers for The MP_REACH and MP_UNREACH attributes are BGP's containers for
carrying opaque information. Each Link State NLRI describes either a carrying opaque information. Each Link State NLRI describes either a
single node or link. single node or link.
All link and node information SHALL be encoded using a TBD AFI / SAFI All link, node and prefix information SHALL be encoded using a TBD
1 or SAFI 128 header into those attributes. SAFI 1 SHALL be used for AFI / TBD SAFI header into those attributes.
Internet routing (Public) and SAFI 128 SHALL be used for VPN routing
(Private) applications.
In order for two BGP speakers to exchange Link-State NLRI, they MUST In order for two BGP speakers to exchange Link-State NLRI, they MUST
use BGP Capabilities Advertisement to ensure that they both are use BGP Capabilities Advertisement to ensure that they both are
capable of properly processing such NLRI. This is done as specified capable of properly processing such NLRI. This is done as specified
in [RFC4760], by using capability code 1 (multi-protocol BGP), with in [RFC4760], by using capability code 1 (multi-protocol BGP), with
an AFI of TBD and an SAFI of 1 or 128. an AFI/SAFI TBD.
The format of the Link State NLRI is shown in the following figure. The format of the Link State NLRI is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Link-State NLRI (variable) | | Link-State NLRI (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Link State SAFI 1 NLRI Format Figure 5: Link State SAFI 1 NLRI Format
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Route Distinguisher + + Route Distinguisher +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Link-State NLRI (variable) | | Link-State NLRI (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Link State SAFI 128 NLRI Format Figure 6: Link State SAFI 128 NLRI Format
The 'Total NLRI Length' field contains the cumulative length of all The 'Total NLRI Length' field contains the cumulative length of all
the TLVs in the NLRI. For VPN applications it also includes the the TLVs in the NLRI. For VPN applications it also includes the
length of the Route Distinguisher. length of the Route Distinguisher.
The 'NLRI Type' field can contain one of the following values: The 'NLRI Type' field can contain one of the following values:
Type = 1: Link NLRI, contains link descriptors and link attributes Type = 1: Link NLRI, contains link descriptors and link attributes
Type = 2: Node NLRI, contains node attributes Type = 2: Node NLRI, contains node attributes
Type = 3: IPv4 Topology Prefix NLRI
Type = 4: IPv6 Topology Prefix NLRI
The Link NLRI (NLRI Type = 1) is shown in the following figure. The Link NLRI (NLRI Type = 1) is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | Instance Identifier | | Protocol-ID | Reserved | Instance Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Descriptors (variable) | | Local Node Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Node Descriptors (variable) | | Remote Node Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Descriptors (variable) | | Link Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: The Link NLRI format Figure 7: The Link NLRI format
The Node NLRI (NLRI Type = 2) is shown in the following figure. The Node NLRI (NLRI Type = 2) is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | Instance Identifier | | Protocol-ID | Reserved | Instance Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Descriptors (variable) | | Local Node Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: The Node NLRI format Figure 8: The Node NLRI format
The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the
same format as shown in the following figure.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | Instance Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node Descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix NLRI (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: The IPv4/IPv6 Topology Prefix NLRI format
The 'Protocol-ID' field can contain one of the following values: The 'Protocol-ID' field can contain one of the following values:
Type = 0: Unknown, The source of NLRI information could not be Protocol-ID = 0: Unknown, The source of NLRI information could not
determined be determined
Type = 1: IS-IS Level 1, The NLRI information has been sourced by Protocol-ID: IS-IS Level 1, The NLRI information has been sourced
IS-IS Level 1 by IS-IS Level 1
Type = 2: IS-IS Level 2, The NLRI information has been sourced by Protocol-ID: IS-IS Level 2, The NLRI information has been sourced
IS-IS Level 2 by IS-IS Level 2
Type = 3: OSPF, The NLRI information has been sourced by OSPF Protocol-ID = 3: OSPF, The NLRI information has been sourced by
OSPF
Type = 4: Direct, The NLRI information has been sourced from local Protocol-ID = 4: Direct, The NLRI information has been sourced
interface state from local interface state
Type = 5: Static, The NLRI information has been sourced by static Protocol-ID = 5: Static, The NLRI information has been sourced by
configuration static configuration
Both OSPF and IS-IS may run multiple routing protocol instances over Both OSPF and IS-IS may run multiple routing protocol instances over
the same link. See [I-D.ietf-isis-mi] and [RFC6549]. The 'Instance the same link. See [I-D.ietf-isis-mi] and [RFC6549]. The 'Instance
Identifier' field identifies the protocol instance. Identifier' field identifies the protocol instance.
Each Node Descriptor and Link Descriptor consists of one or more TLVs Each Node Descriptor and Link Descriptor consists of one or more TLVs
described in the following sections. The sender of an UPDATE message described in the following sections. The sender of an UPDATE message
MUST order the TLVs within a Node Descriptor or a Link Descriptor in MUST order the TLVs within a Node Descriptor or a Link Descriptor in
ascending order of TLV type." ascending order of TLV type."
skipping to change at page 11, line 10 skipping to change at page 12, line 15
be at least one "like" router-ID pair of a Local Node Descriptors and be at least one "like" router-ID pair of a Local Node Descriptors and
a Remote Node Descriptors per-protocol. If a peer sends an illegal a Remote Node Descriptors per-protocol. If a peer sends an illegal
combination in this respect, then this is handled as an NLRI error, combination in this respect, then this is handled as an NLRI error,
described in [RFC4760]. described in [RFC4760].
It is desirable that the Router-ID assignments inside the Node anchor It is desirable that the Router-ID assignments inside the Node anchor
are globally unique. However there may be router-ID spaces (e.g. are globally unique. However there may be router-ID spaces (e.g.
ISO) where not even a global registry exists, or worse, Router-IDs ISO) where not even a global registry exists, or worse, Router-IDs
have been allocated following private-IP RFC 1918 [RFC1918] have been allocated following private-IP RFC 1918 [RFC1918]
allocation. In order to disambiguate the Router-IDs the local and allocation. In order to disambiguate the Router-IDs the local and
remote Autonomous System number TLVs of the anchor nodes may be remote Autonomous System number TLVs of the anchor nodes MUST be
included in the NLRI. If the anchor node's AS is a member of an AS included in the NLRI. If the anchor node's AS is a member of an AS
Confederation ([RFC5065]), then the Autonomous System number TLVs Confederation ([RFC5065]), then the Autonomous System number TLV
contains the confederations' AS Confederation Identifier and the contains the confederations' AS Confederation Identifier and the
Member-AS TLV is included in the NLRI. The Local and Remote Member-AS TLV is included in the NLRI. The Local and Remote
Autonomous System TLVs are 4 octets wide as described in [RFC4893]. Autonomous System TLVs are 4 octets wide as described in [RFC4893].
2-octet AS Numbers SHALL be expanded to 4-octet AS Numbers by zeroing 2-octet AS Numbers SHALL be expanded to 4-octet AS Numbers by zeroing
the two MSB octets. the two MSB octets.
3.2.1.1. Local Node Descriptors 3.2.1.1. Local Node Descriptors
The Local Node Descriptors TLV (Type 256) contains Node Descriptors The Local Node Descriptors TLV (Type 256) contains Node Descriptors
for the node anchoring the local end of the link. The length of this for the node anchoring the local end of the link. The length of this
TLV is variable. The value contains one or more Node Descriptor Sub- TLV is variable. The value contains one or more Node Descriptor Sub-
TLVs defined in Section 3.2.1.3. TLVs defined in Section 3.2.1.3.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Node Descriptor Sub-TLVs (variable) | | Node Descriptor Sub-TLVs (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Local Node Descriptors TLV format Figure 10: Local Node Descriptors TLV format
3.2.1.2. Remote Node Descriptors 3.2.1.2. Remote Node Descriptors
The Remote Node Descriptors TLV (Type 257) contains Node Descriptors The Remote Node Descriptors TLV (Type 257) contains Node Descriptors
for the node anchoring the remote end of the link. The length of for the node anchoring the remote end of the link. The length of
this TLV is variable. The value contains one or more Node Descriptor this TLV is variable. The value contains one or more Node Descriptor
Sub-TLVs defined in Section 3.2.1.3. Sub-TLVs defined in Section 3.2.1.3.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Node Descriptor Sub-TLVs (variable) | | Node Descriptor Sub-TLVs (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Remote Node Descriptors TLV format Figure 11: Remote Node Descriptors TLV format
3.2.1.3. Node Descriptor Sub-TLVs 3.2.1.3. Node Descriptor Sub-TLVs
The Node Descriptor Sub-TLV type codepoints and lengths are listed in The Node Descriptor Sub-TLV type codepoints and lengths are listed in
the following table: the following table:
+------+-------------------+--------+ +------+-------------------+--------+
| Type | Description | Length | | Type | Description | Length |
+------+-------------------+--------+ +------+-------------------+--------+
| 258 | Autonomous System | 4 | | 258 | Autonomous System | 4 |
| 259 | Member-AS | 4 | | 259 | Member-AS | 4 |
| 260 | IPv4 Router-ID | 5 | | 260 | ISO Node-ID | 7 |
| 261 | IPv6 Router-ID | 17 | | 261 | IPv4 Router-ID | 5 |
| 262 | ISO Node-ID | 7 | | 262 | IPv4 Router-ID | 17 |
+------+-------------------+--------+ +------+-------------------+--------+
Table 1: Node Descriptor Sub-TLVs Table 1: Node Descriptor Sub-TLVs
The TLV values in Node Descriptor Sub-TLVs are defined as follows: The TLV values in Node Descriptor Sub-TLVs are defined as follows:
Autonomous System: opaque value (32 Bit AS ID) Autonomous System: opaque value (32 Bit AS ID)
Member-AS: opaque value (32 Bit AS ID); only included if the node is Member-AS: opaque value (32 Bit AS ID); only included if the node is
in an AS confederation. in an AS confederation.
IPv4 Router ID: opaque value (can be an IPv4 address or an 32 Bit IPv4 Router ID: opaque value (can be an IPv4 address or an 32 Bit
router ID) followed by a LAN-ID octet in case LAN "Pseudonode" router ID).
information gets advertised. The PSN octet must be zero for non-
LAN "Pseudonodes".
IPv6 Router ID: opaque value (can be an IPv6 address or 128 Bit IPv6 Router ID: opaque value (can be an IPv6 address or 128 Bit
router ID) followed by a LAN-ID octet in case LAN "Pseudonode" router ID).
information gets advertised. The PSN octet must be zero for non-
LAN "Pseudonodes".
ISO Node ID: ISO node-ID (6 octets ISO system-ID) followed by a PSN ISO Node ID: ISO node-ID (6 octets ISO system-ID) followed by a PSN
octet in case LAN "Pseudonode" information gets advertised. The octet in case LAN "Pseudonode" information gets advertised. The
PSN octet must be zero for non-LAN "Pseudonodes". PSN octet must be zero for non-LAN "Pseudonodes".
There can be at most one instance of each TLV type present in any
Node Descriptor. The TLV ordering within a Node descriptor MUST
be kept in order of increasing numeric value of type. TLVs 258
and 259 specify administrative context in which TLVs 260-262 are
to be evaluated. The first TLV from range 260-262 is to be
interpreted as the primary node identifier, e.g. it acts as the
unique key by which the node can be referenced within its
administrative contexts. Any further TLVs are to be treated as
secondary identifiers, which may be used for cross-reference, but
are to be treated as if they are object attributes.
3.2.1.4. Router-ID Anchoring Example: ISO Pseudonode 3.2.1.4. Router-ID Anchoring Example: ISO Pseudonode
IS-IS Pseudonodes are a good example for the variable Router-ID IS-IS Pseudonodes are a good example for the variable Router-ID
anchoring. Consider Figure 11. This represents a Broadcast LAN anchoring. Consider Figure 12. This represents a Broadcast LAN
between a pair of routers. The "real" (=non pseudonode) routers have between a pair of routers. The "real" (=non pseudonode) routers have
both an IPv4 Router-ID and IS-IS Node-ID. The pseudonode does not both an IPv4 Router-ID and IS-IS Node-ID. The pseudonode does not
have an IPv4 Router-ID. Two unidirectional links (Node1, Pseudonode have an IPv4 Router-ID. Two unidirectional links (Node1, Pseudonode
1) and (Pseudonode 1, Node 2) are being generated. 1) and (Pseudonode 1, Node 2) are being generated.
The NRLI for (Node1, Pseudonode1) encodes local IPv4 router-ID, local The NRLI for (Node1, Pseudonode1) encodes local IPv4 router-ID, local
ISO node-ID and remote ISO node-id) ISO node-ID and remote ISO node-id)
The NLRI for (Pseudonode1, Node2) encodes a local ISO node-ID, remote The NLRI for (Pseudonode1, Node2) encodes a local ISO node-ID and
IPv4 router-ID and remote ISO node-id. remote ISO node-id.
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
| Node1 | | Pseudonode 1 | | Node2 | | Node1 | | Pseudonode 1 | | Node2 |
|1921.6800.1001.00|--->|1921.6800.1001.02|--->|1921.6800.1002.00| |1920.0000.2001.00|--->|1921.6800.1001.02|--->|1920.0000.2002.00|
| 192.168.1.1 | | | | 192.168.1.2 | | 192.0.2.1 | | | | 192.0.2.2 |
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 11: IS-IS Pseudonodes Figure 12: IS-IS Pseudonodes
3.2.1.5. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration 3.2.1.5. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration
Migrating gracefully from one IGP to another requires congruent Migrating gracefully from one IGP to another requires congruent
operation of both routing protocols during the migration period. The operation of both routing protocols during the migration period. The
target protocol (IS-IS) supports more router-ID spaces than the target protocol (IS-IS) supports more router-ID spaces than the
source (OSPFv2) protocol. When advertising a point-to-point link source (OSPFv2) protocol. When advertising a point-to-point link
between an OSPFv2-only router and an OSPFv2 and IS-IS enabled router between an OSPFv2-only router and an OSPFv2 and IS-IS enabled router
the following link information may be generated. Note that the IS-IS the following link information may be generated. Note that the IS-IS
router also supports the IPv6 traffic engineering extensions RFC 6119 router also supports the IPv6 traffic engineering extensions RFC 6119
skipping to change at page 13, line 41 skipping to change at page 15, line 13
ISO node-id and remote IPv6 node-id. ISO node-id and remote IPv6 node-id.
3.2.2. Link Descriptors 3.2.2. Link Descriptors
The 'Link Descriptor' field is a set of Type/Length/Value (TLV) The 'Link Descriptor' field is a set of Type/Length/Value (TLV)
triplets. The format of each TLV is shown in Section 3.1. The 'Link triplets. The format of each TLV is shown in Section 3.1. The 'Link
descriptor' TLVs uniquely identify a link between a pair of anchor descriptor' TLVs uniquely identify a link between a pair of anchor
Routers. A link described by the Link descriptor TLVs actually is a Routers. A link described by the Link descriptor TLVs actually is a
"half-link", a unidirectional representation of a logical link. In "half-link", a unidirectional representation of a logical link. In
order to fully describe a single logical link two originating routers order to fully describe a single logical link two originating routers
need to advertise a half-link each, i.e. two link NLRIs will be need to advertise a half-link each, i.e. two link NLRIs will be
advertised. advertised.
The format and semantics of the 'value' fields in most 'Link The format and semantics of the 'value' fields in most 'Link
Descriptor' TLVs correspond to the format and semantics of value Descriptor' TLVs correspond to the format and semantics of value
fields in IS-IS Extended IS Reachability sub-TLVs, defined in fields in IS-IS Extended IS Reachability sub-TLVs, defined in
[RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link [RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link
Descriptor' TLVs were originally defined for IS-IS, the TLVs can Descriptor' TLVs were originally defined for IS-IS, the TLVs can
carry data sourced either by IS-IS or OSPF. carry data sourced either by IS-IS or OSPF.
The following link descriptor TLVs are valid in the Link NLRI: The following link descriptor TLVs are valid in the Link NLRI:
+--------+--------------------+-----------------+-------------------+ +------+------------------------+-----------------+-----------------+
| Type | Description | IS-IS TLV/Sub- | Value defined in: | | Type | Description | IS-IS | Value defined |
| | | TLV | | | | | TLV/Sub-TLV | in: |
+--------+--------------------+-----------------+-------------------+ +------+------------------------+-----------------+-----------------+
| 263 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | | 263 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | | | | Identifiers | | |
| 264 | IPv4 interface | 22/6 | [RFC5305]/3.2 | | 264 | IPv4 interface address | 22/6 | [RFC5305]/3.2 |
| | address | | | | 265 | IPv4 neighbor address | 22/8 | [RFC5305]/3.3 |
| 265 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 | | 266 | IPv6 interface address | 22/12 | [RFC6119]/4.2 |
| | address | | | | 267 | IPv6 neighbor address | 22/13 | [RFC6119]/4.3 |
| 266 | IPv6 interface | 22/12 | [RFC6119]/4.2 | | 268 | Multi Topology ID | --- | Section 3.2.2.1 |
| | address | | | +------+------------------------+-----------------+-----------------+
| 267 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
| 268 | Multi Topology ID | --- | Section 3.2.2.1 |
+--------+--------------------+-----------------+-------------------+
Table 2: Link Descriptor TLVs Table 2: Link Descriptor TLVs
3.2.2.1. Multi Topology ID TLV 3.2.2.1. Multi Topology ID TLV
The Multi Topology ID TLV (Type 268) carries the Multi Topology ID The Multi Topology ID TLV (Type 268) carries the Multi Topology ID
for this link. The semantics of the Multi Topology ID are defined in for this link. The semantics of the Multi Topology ID are defined in
RFC5120, Section 7.2 [RFC5120], and the OSPF Multi Topology ID), RFC5120, Section 7.2 [RFC5120], and the OSPF Multi Topology ID),
defined in RFC4915, Section 3.7 [RFC4915]. If the value in the Multi defined in RFC4915, Section 3.7 [RFC4915]. If the value in the Multi
Topology ID TLV is derived from OSPF, then the upper 9 bits of the Topology ID TLV is derived from OSPF, then the upper 9 bits of the
Multi Topology ID are set to 0. Multi Topology ID are set to 0.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi Topology ID | |R R R R| Multi Topology ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Multi Topology ID TLV format Figure 13: Multi Topology ID TLV format
3.2.3. The Prefix NLRI
The Prefix NLRI is a variable length field that contains an IP
address prefix (IPv4 or IPv6) originally advertised in the IGP
topology. The distinction between IPv4 and IPv6 prefixes is given by
the NLRI Type filed in the Link State NLRI. Reachability information
is encoded as one or more 2-tuples of the form <length, prefix>,
whose fields are described below:
+---------------------------+
| Length (1 octet) |
+---------------------------+
| Prefix (variable) |
+---------------------------+
Figure 14: Prefix NLRI format
3.3. The LINK_STATE Attribute 3.3. The LINK_STATE Attribute
This is an optional non-transitive BGP attribute that is used to This is an optional, transitive BGP attribute that is used to carry
carry link and node link-state parameters and attributes. It is link, node and prefix parameters and attributes. It is defined as a
defined as a set of Type/Length/Value (TLV) triplets, described in set of Type/Length/Value (TLV) triplets, described in the following
the following section. This attribute SHOULD only be included with section. This attribute SHOULD only be included with Link State
Link State NLRIs. This attribute MUST be ignored for all other NLRI NLRIs. This attribute MUST be ignored for all other NLRIs.
types.
3.3.1. Link Attribute TLVs 3.3.1. Link Attribute TLVs
Each 'Link Attribute' is a Type/Length/Value (TLV) triplet formatted Each 'Link Attribute' is a Type/Length/Value (TLV) triplet formatted
as defined in Section 3.1. The format and semantics of the 'value' as defined in Section 3.1. The format and semantics of the 'value'
fields in some 'Link Attribute' TLVs correspond to the format and fields in some 'Link Attribute' TLVs correspond to the format and
semantics of value fields in IS-IS Extended IS Reachability sub-TLVs, semantics of value fields in IS-IS Extended IS Reachability sub-TLVs,
defined in [RFC5305] and [RFC5307]. Other 'Link Attribute' TLVs are defined in [RFC5305] and [RFC5307]. Other 'Link Attribute' TLVs are
defined in this document. Although the encodings for 'Link defined in this document. Although the encodings for 'Link
Attribute' TLVs were originally defined for IS-IS, the TLVs can carry Attribute' TLVs were originally defined for IS-IS, the TLVs can carry
data sourced either by IS-IS or OSPF. data sourced either by IS-IS or OSPF.
The following 'Link Attribute' TLVs are are valid in the LINK_STATE The following 'Link Attribute' TLVs are are valid in the LINK_STATE
attribute: attribute:
+------+----------------------+-----------------+-------------------+ +------+-------------------------+----------------+-----------------+
| Type | Description | IS-IS TLV/Sub- | Defined in: | | Type | Description | IS-IS | Defined in: |
| | | TLV | | | | | TLV/Sub-TLV | |
+------+----------------------+-----------------+-------------------+ +------+-------------------------+----------------+-----------------+
| 269 | Administrative group | 22/3 | [RFC5305]/3.1 | | 269 | Administrative group | 22/3 | [RFC5305]/3.1 |
| | (color) | | | | | (color) | | |
| 270 | Maximum link | 22/9 | [RFC5305]/3.3 | | 270 | Maximum link bandwidth | 22/9 | [RFC5305]/3.3 |
| | bandwidth | | | | 271 | Max. reservable link | 22/10 | [RFC5305]/3.5 |
| 271 | Max. reservable link | 22/10 | [RFC5305]/3.5 | | | bandwidth | | |
| | bandwidth | | | | 272 | Unreserved bandwidth | 22/11 | [RFC5305]/3.6 |
| 272 | Unreserved bandwidth | 22/11 | [RFC5305]/3.6 | | 273 | Link Protection Type | 22/20 | [RFC5307]/1.2 |
| 273 | Link Protection Type | 22/20 | [RFC5307]/1.2 | | 274 | MPLS Protocol Mask | --- | Section 3.3.1.1 |
| 274 | MPLS Protocol Mask | --- | Section 3.3.1.1 | | 275 | Metric | --- | Section 3.3.1.2 |
| 275 | Metric | --- | Section 3.3.1.2 | | 276 | Shared Risk Link Group | --- | Section 3.3.1.3 |
| 276 | Shared Risk Link | --- | Section 3.3.1.3 | | 277 | OSPF specific link | --- | Section 3.3.1.4 |
| | Group | | | | | attribute | | |
| 277 | OSPF specific link | --- | Section 3.3.1.4 | | 278 | IS-IS Specific Link | --- | Section 3.3.1.5 |
| | attribute | | | | | Attribute | | |
| 278 | IS-IS Specific Link | --- | Section 3.3.1.5 | | 279 | Area ID | --- | Section 3.3.1.6 |
| | Attribute | | | +------+-------------------------+----------------+-----------------+
| 279 | Area ID | --- | Section 3.3.1.6 |
+------+----------------------+-----------------+-------------------+
Table 3: Link Attribute TLVs Table 3: Link Attribute TLVs
3.3.1.1. MPLS Protocol Mask TLV 3.3.1.1. MPLS Protocol Mask TLV
The MPLS Protocol TLV (Type 274) carries a bit mask describing which The MPLS Protocol TLV (Type 274) carries a bit mask describing which
MPLS signaling protocols are enabled. The length of this TLV is 1. MPLS signaling protocols are enabled. The length of this TLV is 1.
The value is a bit array of 8 flags, where each bit represents an The value is a bit array of 8 flags, where each bit represents an
MPLS Protocol capability. MPLS Protocol capability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L R | |L R |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 13: MPLS Protocol TLV Figure 15: MPLS Protocol TLV
The following bits are defined: The following bits are defined:
+-----+---------------------------------------------+-----------+ +-----+---------------------------------------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+-----+---------------------------------------------+-----------+ +-----+---------------------------------------------+-----------+
| 0 | Label Distribution Protocol (LDP) | [RFC5036] | | 0 | Label Distribution Protocol (LDP) | [RFC5036] |
| 1 | Extension to RSVP for LSP Tunnels (RSVP-TE) | [RFC3209] | | 1 | Extension to RSVP for LSP Tunnels (RSVP-TE) | [RFC3209] |
| 2-7 | Reserved for future use | | | 2-7 | Reserved for future use | |
+-----+---------------------------------------------+-----------+ +-----+---------------------------------------------+-----------+
Table 4: MPLS Protocol Mask TLV Codes Table 4: MPLS Protocol Mask TLV Codes
3.3.1.2. Metric TLV 3.3.1.2. Metric TLV
The IGP Metric TLV (Type 275) carries the metric for this link. The The IGP Metric TLV (Type 275) carries the metric for this link. The
length of this TLV is 3. If the length of the metric from which the length of this TLV is 3. If the length of the metric from which the
IGP Metric value is derived is less than 3 (e.g. for OSPF link IGP Metric value is derived is less than 3 (e.g. for OSPF link
metrics or non-wide IS-IS metric), then the upper bits of the TLV are metrics or non-wide IS-IS metric), then the upper bits of the TLV are
set to 0. set to 0.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IGP Link Metric | | IGP Link Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Metric TLV format Figure 16: Metric TLV format
3.3.1.3. Shared Risk Link Group TLV 3.3.1.3. Shared Risk Link Group TLV
The Shared Risk Link Group (SRLG) TLV (Type 276) carries the Shared The Shared Risk Link Group (SRLG) TLV (Type 276) carries the Shared
Risk Link Group information (see Section 2.3, "Shared Risk Link Group Risk Link Group information (see Section 2.3, "Shared Risk Link Group
Information", of [RFC4202]). It contains a data structure consisting Information", of [RFC4202]). It contains a data structure consisting
of a (variable) list of SRLG values, where each element in the list of a (variable) list of SRLG values, where each element in the list
has 4 octets, as shown in Figure 15. The length of this TLV is 4 * has 4 octets, as shown in Figure 17. The length of this TLV is 4 *
(number of SRLG values). (number of SRLG values).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ............ | | ............ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Shared Risk Link Group TLV format Figure 17: Shared Risk Link Group TLV format
Note that there is no SRLG TLV in OSPF-TE. In IS-IS the SRLG Note that there is no SRLG TLV in OSPF-TE. In IS-IS the SRLG
information is carried in two different TLVs: the IPv4 (SRLG) TLV information is carried in two different TLVs: the IPv4 (SRLG) TLV
(Type 138) defined in [RFC5307], and the IPv6 SRLG TLV (Type 139) (Type 138) defined in [RFC5307], and the IPv6 SRLG TLV (Type 139)
defined in [RFC6119]. Since the Link State NLRI uses variable defined in [RFC6119]. Since the Link State NLRI uses variable
Router-ID anchoring, both IPv4 and IPv6 SRLG information can be Router-ID anchoring, both IPv4 and IPv6 SRLG information can be
carried in a single TLV. carried in a single TLV.
3.3.1.4. OSPF Specific Link Attribute TLV 3.3.1.4. OSPF Specific Link Attribute TLV
The OSPF specific link attribute TLV (Type 277) is an envelope that The OSPF specific link attribute TLV (Type 277) is an envelope that
transparently carries optional link properties TLVs advertised by an transparently carries optional link properties TLVs advertised by an
OSPF router. The value field contains one or more optional OSPF link OSPF router. The value field contains one or more optional OSPF link
attribute TLVs. An originating router shall use this TLV for attribute TLVs. An originating router shall use this TLV for
encoding information specific to the OSPF protocol or new OSPF encoding information specific to the OSPF protocol or new OSPF
extensions for which there is no protocol neutral representation in extensions for which there is no protocol neutral representation in
the BGP link-state NLRI. the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| OSPF specific link attributes (variable) | | OSPF specific link attributes (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: OSPF specific link attribute format Figure 18: OSPF specific link attribute format
3.3.1.5. IS-IS specific link attribute TLV 3.3.1.5. IS-IS specific link attribute TLV
The IS-IS specific link attribute TLV (Type 278) is an envelope that The IS-IS specific link attribute TLV (Type 278) is an envelope that
transparently carries optional link properties TLVs advertised by an transparently carries optional link properties TLVs advertised by an
IS-IS router. The value field contains one or more optional IS-IS IS-IS router. The value field contains one or more optional IS-IS
link attribute TLVs. An originating router shall use this TLV for link attribute TLVs. An originating router shall use this TLV for
encoding information specific to the IS-IS protocol or new IS-IS encoding information specific to the IS-IS protocol or new IS-IS
extensions for which there is no protocol neutral representation in extensions for which there is no protocol neutral representation in
the BGP link-state NLRI. the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| IS-IS specific link attributes (variable) | | IS-IS specific link attributes (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: IS-IS specific link attribute format Figure 19: IS-IS specific link attribute format
3.3.1.6. Link Area TLV 3.3.1.6. Link Area TLV
The Area TLV (Type 279) carries the Area ID which is assigned on this The Area TLV (Type 279) carries the Area ID which is assigned on this
link. If a link is present in more than one Area then several link. If a link is present in more than one Area then several
occurrences of this TLV may be generated. Since only the OSPF occurrences of this TLV may be generated. Since only the OSPF
protocol carries the notion of link specific areas, the Area ID has a protocol carries the notion of link specific areas, the Area ID has a
fixed length of 4 octets. fixed length of 4 octets.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area ID | | Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: Link Area TLV format Figure 20: Link Area TLV format
3.3.2. Node Attribute TLVs 3.3.2. Node Attribute TLVs
The following node attribute TLVs are defined: The following node attribute TLVs are defined:
+------+--------------------------------+----------+ +------+--------------------------------+----------+
| Type | Description | Length | | Type | Description | Length |
+------+--------------------------------+----------+ +------+--------------------------------+----------+
| 280 | Multi Topology | 2 | | 280 | Multi Topology | 2 |
| 281 | Node Flag Bits | 1 | | 281 | Node Flag Bits | 1 |
| 282 | OSPF Specific Node Properties | variable | | 282 | OSPF Specific Node Properties | variable |
| 283 | IS-IS Specific Node Properties | variable | | 283 | IS-IS Specific Node Properties | variable |
| 284 | Node Area ID | variable | | 284 | Node Area ID | variable |
+------+--------------------------------+----------+ +------+--------------------------------+----------+
Table 5: Node Attribute TLVs Table 5: Node Attribute TLVs
3.3.2.1. Multi Topology Node TLV 3.3.2.1. Multi Topology Node TLV
The Multi Topology TLV (Type 280) carries the Multi Topology ID and The Multi Topology TLV (Type 280) carries the Multi Topology ID and
topology specific flags for this node. The format and semantics of topology specific flags for this node. The format and semantics of
the 'value' field in the Multi Topology TLV is defined in RFC5120, the 'value' field in the Multi Topology TLV is defined in RFC5120,
Section 7.1 [RFC5120]. If the value in the Multi Topology TLV is Section 7.1 [RFC5120]. If the value in the Multi Topology TLV is
derived from OSPF, then the upper 9 bits of the Multi Topology ID and derived from OSPF, then the upper 9 bits of the Multi Topology ID and
the 'O' and 'A' bits are set to 0. the 'O' and 'A' bits are set to 0.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O A R R| Multi Topology ID | |O A R R| Multi Topology ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 19: Multi Topology Node TLV format Figure 21: Multi Topology Node TLV format
3.3.2.2. Node Flag Bits TLV 3.3.2.2. Node Flag Bits TLV
The Node Flag Bits TLV (Type 281) carries a bit mask describing node The Node Flag Bits TLV (Type 281) carries a bit mask describing node
attributes. The value is a bit array of 8 flags, where each bit attributes. The value is a bit array of 8 flags, where each bit
represents an MPLS Protocol capability. represents a node capability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | | Flags |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 20: Node Flag Bits TLV format Figure 22: Node Flag Bits TLV format
The bits are defined as follows: The bits are defined as follows:
+-----+--------------+-----------+ +-----+--------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+-----+--------------+-----------+ +-----+--------------+-----------+
| 0 | Overload Bit | [RFC1195] | | 0 | Overload Bit | [RFC1195] |
| 1 | Attached Bit | [RFC1195] | | 1 | Attached Bit | [RFC1195] |
| 2 | External Bit | [RFC2328] | | 2 | External Bit | [RFC2328] |
| 3 | ABR Bit | [RFC2328] | | 3 | ABR Bit | [RFC2328] |
+-----+--------------+-----------+ +-----+--------------+-----------+
Table 6: Node Flag Bits Definitions Table 6: Node Flag Bits Definitions
3.3.2.3. OSPF Specific Node Properties TLV 3.3.2.3. OSPF Specific Node Properties TLV
The OSPF Specific Node Properties TLV (Type 282) is an envelope that The OSPF Specific Node Properties TLV (Type 282) is an envelope that
transparently carries optional node properties TLVs advertised by an transparently carries optional node properties TLVs advertised by an
OSPF router. The value field contains one or more optional OSPF node OSPF router. The value field contains one or more optional OSPF node
property TLVs, such as the OSPF Router Informational Capabilities TLV property TLVs, such as the OSPF Router Informational Capabilities TLV
defined in [RFC4970], or the OSPF TE Node Capability Descriptor TLV defined in [RFC4970], or the OSPF TE Node Capability Descriptor TLV
described in [RFC5073]. An originating router shall use this TLV for described in [RFC5073]. An originating router shall use this TLV for
encoding information specific to the OSPF protocol or new OSPF encoding information specific to the OSPF protocol or new OSPF
extensions for which there is no protocol neutral representation in extensions for which there is no protocol neutral representation in
the BGP link-state NLRI. the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| OSPF specific node properties (variable) | | OSPF specific node properties (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: OSPF specific Node property format Figure 23: OSPF specific Node property format
3.3.2.4. IS-IS Specific Node Properties TLV 3.3.2.4. IS-IS Specific Node Properties TLV
The IS-IS Router Specific Node Properties TLV (Type 283) is an The IS-IS Router Specific Node Properties TLV (Type 283) is an
envelope that transparently carries optional node specific TLVs envelope that transparently carries optional node specific TLVs
advertised by an IS-IS router. The value field contains one or more advertised by an IS-IS router. The value field contains one or more
optional IS-IS node property TLVs, such as the IS-IS TE Node optional IS-IS node property TLVs, such as the IS-IS TE Node
Capability Descriptor TLV described in [RFC5073]. An originating Capability Descriptor TLV described in [RFC5073]. An originating
router shall use this TLV for encoding information specific to the router shall use this TLV for encoding information specific to the
IS-IS protocol or new IS-IS extensions for which there is no protocol IS-IS protocol or new IS-IS extensions for which there is no protocol
neutral representation in the BGP link-state NLRI. neutral representation in the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| IS-IS specific node properties (variable) | | IS-IS specific node properties (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: IS-IS specific Node property format Figure 24: IS-IS specific Node property format
3.3.2.5. Area Node TLV 3.3.2.5. Area Node TLV
The Area TLV (Type 284) carries the Area ID which is assigned to this The Area TLV (Type 284) carries the Area ID which is assigned to this
node. If a node is present in more than one Area then several node. If a node is present in more than one Area then several
occurrences of this TLV may be generated. Since only the IS-IS occurrences of this TLV may be generated. Since only the IS-IS
protocol carries the notion of per-node areas, the Area ID has a protocol carries the notion of per-node areas, the Area ID has a
variable length of 1 to 20 octets. variable length of 1 to 20 octets.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Area ID (variable) | | Area ID (variable) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 23: Area Node TLV format Figure 25: Area Node TLV format
3.4. Inter-AS Links 3.3.3. Prefix Attributes TLVs
Prefixes are learned from the IGP topology (ISIS or OSPF) with a set
of IGP attributes (such as metric, route tags, route type, etc.) that
MUST be reflected into the LINK_STATE attribute. This section
describes the different attributes related to the IPv4/IPv6 prefixes.
Prefix Attributes TLVs SHOULD be used when advertising NLRI types 3
and 4 only. The following attributes TLVs are defined:
+------+-------------------------+--------+-----------+
| Type | Description | Length | Reference |
+------+-------------------------+--------+-----------+
| 285 | IGP Flags | 4 | |
| 286 | Route Tag | 4 | [RFC5130] |
| 287 | Extended Tag | 8 | [RFC5130] |
| 288 | Metric | 4 | [RFC5305] |
| 289 | OSPF Forwarding Address | 4 | [RFC2328] |
+------+-------------------------+--------+-----------+
Table 7: Prefix Attribute TLVs
3.3.3.1. IGP Flags TLV
IGP Flags TLV contains ISIS and OSPF flags and bits originally
assigned to the prefix. The IGP Flags TLV is encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IGP Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: IGP Flag TLV format
where:
Type is 285
Length is 4
The following bits are defined according to the table here below:
+------+------------------+-----------+
| Bit | Description | Reference |
+------+------------------+-----------+
| 0 | ISIS Up/Down Bit | [RFC5305] |
| 1-3 | OSPF Route Type | [RFC2328] |
| 4-15 | RESERVED | |
+------+------------------+-----------+
Table 8: IGP Flag Bits Definitions
OSPF Route Type can be either: Intra-Area (0x1), Inter-Area (0x2),
External 1 (0x3), External 2 (0x4), NSSA (0x5) and is encoded in a 3
bits number. For prefixes learned from IS-IS, this field MUST to be
set to 0x0 on transmission.
3.3.3.2. Route Tag
Route Tag TLV carries the original IGP TAG (ISIS or OSPF) of the
prefix and is encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 27: IGP Route TAG TLV format
where:
Type is 286
Length is 4
Route Tag contains the original tags as learned in the IGP topology.
3.3.3.3. Extended Route Tag
Extended Route Tag TLV carries the ISIS Extended Route TAG of the
prefix and is encoded as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Route Tag |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 28: Extended IGP Route TAG TLV format
where:
Type is 287
Length is 8
Extended Route Tag contains the original ISIS Extended Tag as learned
in the IGP topology.
3.3.3.4. Prefix Metric TLV
Prefix Metric TLV carries the metric of the prefix as known in the
IGP topology. The attribute is mandatory and can only appear once.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: Prefix Metric TLV Format
where:
Type is 288
Length is 4
3.3.3.5. OSPF Forwarding Address TLV
OSPF Forwarding Address TLV carries the OSPF forwarding address as
known in the original OSPF advertisement. Forwarding address can be
either IPv4 or IPv6.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forwarding Address (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 30: OSPF Forwarding Address TLV Format
where:
Type is 289
Length is 4 for an IPv4 forwarding address an 16 for an IPv6
forwarding address
3.4. BGP Next Hop Information
BGP link-state information for both IPv4 and IPv6 networks can be
carried over either an IPv4 BGP session, or an IPv6 BGP session. If
IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI
SHOULD be an IPv4 address. Similarly, if IPv6 BGP session is used,
then the next hop in the MP_REACH_NLRI SHOULD be an IPv6 address.
Usually the next hop will be set to the local end-point address of
the BGP session. The next hop address MUST be encoded as described
in [RFC4760]. The length field of the next hop address will specify
the next hop address-family. If the next hop length is 4, then the
next hop is an IPv4 address; if the next hop length is 16, then it is
a global IPv6 address and if the next hop length is 32, then there is
one global IPv6 address followed by a link-local IPv6 address. The
link-local IPv6 address should be used as described in [RFC2545].
3.5. Inter-AS Links
The main source of TE information is the IGP, which is not active on The main source of TE information is the IGP, which is not active on
inter-AS links. In order to inject a non-IGP enabled link into the inter-AS links. In order to inject a non-IGP enabled link into the
BGP link-state RIB an implementation must support configuration of BGP link-state RIB an implementation must support configuration of
static links. static links.
4. Link to Path Aggregation 4. Link to Path Aggregation
Distribution of all links available in the global Internet is Distribution of all links available in the global Internet is
certainly possible, however not desirable from a scaling and privacy certainly possible, however not desirable from a scaling and privacy
skipping to change at page 21, line 42 skipping to change at page 27, line 45
of nodes. The "aggregate link" represents the aggregated set of link of nodes. The "aggregate link" represents the aggregated set of link
properties between a pair of non-adjacent nodes. The actual methods properties between a pair of non-adjacent nodes. The actual methods
to compute the path properties (of bandwidth, metric) are outside the to compute the path properties (of bandwidth, metric) are outside the
scope of this document. The decision whether to advertise all scope of this document. The decision whether to advertise all
specific links or aggregated links is an operator's policy choice. specific links or aggregated links is an operator's policy choice.
To highlight the varying levels of exposure, the following deployment To highlight the varying levels of exposure, the following deployment
examples shall be discussed. examples shall be discussed.
4.1. Example: No Link Aggregation 4.1. Example: No Link Aggregation
Consider Figure 24. Both AS1 and AS2 operators want to protect their Consider Figure 31. Both AS1 and AS2 operators want to protect their
inter-AS {R1,R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants to inter-AS {R1,R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants to
compute its link-protection LSP to R3 it needs to "see" an alternate compute its link-protection LSP to R3 it needs to "see" an alternate
path to R3. Therefore the AS2 operator exposes its topology. All BGP path to R3. Therefore the AS2 operator exposes its topology. All
TE enabled routers in AS1 "see" the full topology of AS and therefore BGP TE enabled routers in AS1 "see" the full topology of AS and
can compute a backup path. Note that the decision if the direct link therefore can compute a backup path. Note that the decision if the
between {R3, R4} or the {R4, R5, R3) path is used is made by the direct link between {R3, R4} or the {R4, R5, R3) path is used is made
computing router. by the computing router.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | \ | : | \
| : | R5 | : | R5
| : | / | : | /
R2-------R4 R2-------R4
: :
: :
Figure 24: no-link-aggregation Figure 31: no-link-aggregation
4.2. Example: ASBR to ASBR Path Aggregation 4.2. Example: ASBR to ASBR Path Aggregation
The brief difference between the "no-link aggregation" example and The brief difference between the "no-link aggregation" example and
this example is that no specific link gets exposed. Consider Figure this example is that no specific link gets exposed. Consider
25. The only link which gets advertised by AS2 is an "aggregate" link Figure 32. The only link which gets advertised by AS2 is an
between R3 and R4. This is enough to tell AS1 that there is a backup "aggregate" link between R3 and R4. This is enough to tell AS1 that
path. However the actual links being used are hidden from the there is a backup path. However the actual links being used are
topology. hidden from the topology.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | | : |
| : | | : |
| : | | : |
R2-------R4 R2-------R4
: :
: :
Figure 25: asbr-link-aggregation Figure 32: asbr-link-aggregation
4.3. Example: Multi-AS Path Aggregation 4.3. Example: Multi-AS Path Aggregation
Service providers in control of multiple ASes may even decide to not Service providers in control of multiple ASes may even decide to not
expose their internal inter-AS links. Consider Figure 26. Rather expose their internal inter-AS links. Consider Figure 33. Rather
than exposing all specific R3 to R6 links, AS3 is modeled as a single than exposing all specific R3 to R6 links, AS3 is modeled as a single
node which connects to the border routers of the aggregated domain. node which connects to the border routers of the aggregated domain.
AS1 : AS2 : AS3 AS1 : AS2 : AS3
: : : :
R1-------R3----- R1-------R3-----
| : : \ | : : \
| : : vR0 | : : vR0
| : : / | : : /
R2-------R4----- R2-------R4-----
: : : :
: : : :
Figure 26: multi-as-aggregation Figure 33: multi-as-aggregation
5. IANA Considerations 5. IANA Considerations
This document requests a code point from the registry of Address This document requests a code point from the registry of Address
Family Numbers. Family Numbers.
This document requests a code point from the BGP Path Attributes This document requests a code point from the BGP Path Attributes
registry. registry.
This document requests creation of a new registry for node anchor, This document requests creation of a new registry for node anchor,
link descriptor and link attribute TLVs. Values 0-255 are reserved. link descriptor and link attribute TLVs. Values 0-255 are reserved.
Values 256-65535 will be used for Codepoints. The registry will be Values 256-65535 will be used for Codepoints. The registry will be
initialized as shown in Table 2 and Table 3. Allocations within the initialized as shown in Table 2 and Table 3. Allocations within the
registry will require documentation of the proposed use of the registry will require documentation of the proposed use of the
allocated value and approval by the Designated Expert assigned by the allocated value and approval by the Designated Expert assigned by the
IESG (see [RFC5226]). IESG (see [RFC5226]).
Note to RFC Editor: this section may be removed on publication as an Note to RFC Editor: this section may be removed on publication as an
RFC. RFC.
6. Manageability Considerations 6. Manageability Considerations
This section is structured as recommended in [RFC5706]. This section is structured as recommended in [RFC5706].
skipping to change at page 25, line 36 skipping to change at page 32, line 23
Procedures and protocol extensions defined in this document do not Procedures and protocol extensions defined in this document do not
affect the BGP security model. affect the BGP security model.
A BGP Speaker SHOULD NOT accept updates from a Consumer peer. A BGP Speaker SHOULD NOT accept updates from a Consumer peer.
An operator SHOULD employ a mechanism to protect a BGP Speaker An operator SHOULD employ a mechanism to protect a BGP Speaker
against DDOS attacks from Consumers. against DDOS attacks from Consumers.
8. Acknowledgements 8. Acknowledgements
We would like to thank Nischal Sheth for contributions to this We would like to thank Nischal Sheth, Alia Atlas, Robert Varga, David
document. Ward, Derek Yeung, Murtuza Lightwala, John Scudder, Kaliraj
Vairavakkalai, Les Ginsberg, Liem Nguyen, Manish Bhardwaj, Mike
We would like to thank Alia Atlas, David Ward, Derek Yeung, Murtuza Shand, Peter Psenak, Rex Fernando, Richard Woundy, Saikat Ray, Steven
Lightwala, John Scudder, Kaliraj Vairavakkalai, Les Ginsberg, Liem Luong, Tamas Mondal, Waqas Alam, and Yakov Rekhter for their
Nguyen, Manish Bhardwaj, Mike Shand, Peter Psenak, Rex Fernando, comments.
Richard Woundy, Robert Varga, Saikat Ray, Steven Luong, Tamas Mondal,
Waqas Alam, and Yakov Rekhter for their comments.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990. dual environments", RFC 1195, December 1990.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP E. Lear, "Address Allocation for Private Internets",
5, RFC 1918, February 1996. BCP 5, RFC 1918, February 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
Extensions for IPv6 Inter-Domain Routing", RFC 2545,
March 1999.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005. (GMPLS)", RFC 4202, October 2005.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January "Multiprotocol Extensions for BGP-4", RFC 4760,
2007. January 2007.
[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
Number Space", RFC 4893, May 2007. Number Space", RFC 4893, May 2007.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
4915, June 2007. RFC 4915, June 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007. Specification", RFC 5036, October 2007.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, August 2007. System Confederations for BGP", RFC 5065, August 2007.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, February 2008. Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
[RFC5130] Previdi, S., Shand, M., and C. Martin, "A Policy Control
Mechanism in IS-IS Using Administrative Tags", RFC 5130,
February 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008. Engineering", RFC 5305, October 2008.
[RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support [RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 5307, October 2008. RFC 5307, October 2008.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, February 2011. Engineering in IS-IS", RFC 6119, February 2011.
9.2. Informative References 9.2. Informative References
[I-D.ietf-alto-protocol] [I-D.ietf-alto-protocol]
Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol",
Internet-Draft draft-ietf-alto-protocol-11, March 2012. draft-ietf-alto-protocol-13 (work in progress),
September 2012.
[I-D.ietf-isis-mi] [I-D.ietf-isis-mi]
Roy, A., Ward, D., Ginsberg, L., Shand, M., and S. Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D.
Previdi, "IS-IS Multi-Instance", Internet-Draft draft- Ward, "IS-IS Multi-Instance", draft-ietf-isis-mi-08 (work
ietf-isis-mi-06, February 2012. in progress), October 2012.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Computation Element (PCE)-Based Architecture", RFC 4655, Element (PCE)-Based Architecture", RFC 4655, August 2006.
August 2006.
[RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.
Shaffer, "Extensions to OSPF for Advertising Optional Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 4970, July 2007. Router Capabilities", RFC 4970, July 2007.
[RFC5073] Vasseur, J.P. and J.L. Le Roux, "IGP Routing Protocol [RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol
Extensions for Discovery of Traffic Engineering Node Extensions for Discovery of Traffic Engineering Node
Capabilities", RFC 5073, December 2007. Capabilities", RFC 5073, December 2007.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain
Path Computation Method for Establishing Inter-Domain Path Computation Method for Establishing Inter-Domain
Traffic Engineering (TE) Label Switched Paths (LSPs)", RFC Traffic Engineering (TE) Label Switched Paths (LSPs)",
5152, February 2008. RFC 5152, February 2008.
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693, October Optimization (ALTO) Problem Statement", RFC 5693,
2009. October 2009.
[RFC5706] Harrington, D., "Guidelines for Considering Operations and [RFC5706] Harrington, D., "Guidelines for Considering Operations and
Management of New Protocols and Protocol Extensions", RFC Management of New Protocols and Protocol Extensions",
5706, November 2009. RFC 5706, November 2009.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi- [RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, March 2012. Instance Extensions", RFC 6549, March 2012.
Authors' Addresses Authors' Addresses
Hannes Gredler Hannes Gredler
Juniper Networks, Inc. Juniper Networks, Inc.
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US US
Email: hannes@juniper.net Email: hannes@juniper.net
Jan Medved Jan Medved
Cisco Systems, Inc. Cisco Systems, Inc.
170, West Tasman Drive 170, West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
US US
Email: jmedved@cisco.com Email: jmedved@cisco.com
Stefano Previdi Stefano Previdi
Cisco Systems, Inc. Cisco Systems, Inc.
Via Del Serafico, 200 Via Del Serafico, 200
Roma 00142 Rome 00142
Italy Italy
Email: sprevidi@cisco.com Email: sprevidi@cisco.com
Adrian Farrel Adrian Farrel
Juniper Networks, Inc. Juniper Networks, Inc.
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US US
Email: afarrel@juniper.net Email: afarrel@juniper.net
Saikat Ray
Cisco Systems, Inc.
170, West Tasman Drive
San Jose, CA 95134
US
Email: sairay@cisco.com
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