rfc9346v2.txt   rfc9346.txt 
Internet Engineering Task Force (IETF) M. Chen Internet Engineering Task Force (IETF) M. Chen
Request for Comments: 9346 Huawei Request for Comments: 9346 Huawei
Obsoletes: 5316 L. Ginsberg Obsoletes: 5316 L. Ginsberg
Category: Standards Track Cisco Systems Category: Standards Track Cisco Systems
ISSN: 2070-1721 S. Previdi ISSN: 2070-1721 S. Previdi
Huawei Technologies Huawei Technologies
D. Xiaodong X. Duan
China Mobile China Mobile
January 2023 January 2023
IS-IS Extensions in Support of Inter-Autonomous System (AS) MPLS and IS-IS Extensions in Support of Inter-Autonomous System (AS) MPLS and
GMPLS Traffic Engineering GMPLS Traffic Engineering
Abstract Abstract
This document describes extensions to the Intermediate System to This document describes extensions to the Intermediate System to
Intermediate System (IS-IS) protocol to support Multiprotocol Label Intermediate System (IS-IS) protocol to support Multiprotocol Label
skipping to change at line 71 skipping to change at line 71
Table of Contents Table of Contents
1. Introduction 1. Introduction
1.1. Requirements Language 1.1. Requirements Language
2. Problem Statement 2. Problem Statement
2.1. A Note on Non-objectives 2.1. A Note on Non-objectives
2.2. Per-Domain Path Determination 2.2. Per-Domain Path Determination
2.3. Backward-Recursive Path Computation 2.3. Backward-Recursive Path Computation
3. Extensions to IS-IS TE 3. Extensions to IS-IS TE
3.1. Choosing the TE Router ID Value 3.1. Choosing the TE Router ID Value
3.2. Inter-AS Reachability TLV 3.2. Inter-AS Reachability Information TLV
3.3. TE Router ID 3.3. TE Router ID
3.4. Sub-TLVs for Inter-AS Reachability TLV 3.4. Sub-TLVs for Inter-AS Reachability Information TLV
3.4.1. Remote AS Number Sub-TLV 3.4.1. Remote AS Number Sub-TLV
3.4.2. IPv4 Remote ASBR ID Sub-TLV 3.4.2. IPv4 Remote ASBR Identifier Sub-TLV
3.4.3. IPv6 Remote ASBR ID Sub-TLV 3.4.3. IPv6 Remote ASBR Identifier Sub-TLV
3.4.4. IPv6 Local ASBR ID Sub-TLV 3.4.4. IPv6 Local ASBR Identifier Sub-TLV
3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV 3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV
3.5.1. IPv4 TE Router ID Sub-TLV 3.5.1. IPv4 TE Router ID Sub-TLV
3.5.2. IPv6 TE Router ID Sub-TLV 3.5.2. IPv6 TE Router ID Sub-TLV
4. Procedure for Inter-AS TE Links 4. Procedure for Inter-AS TE Links
4.1. Origin of Proxied TE Information 4.1. Origin of Proxied TE Information
5. Security Considerations 5. Security Considerations
6. IANA Considerations 6. IANA Considerations
6.1. Inter-AS Reachability TLV 6.1. Inter-AS Reachability Information TLV
6.2. Sub-TLVs for the Inter-AS Reachability TLV 6.2. Sub-TLVs for the Inter-AS Reachability Information TLV
6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV 6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV
7. References 7. References
7.1. Normative References 7.1. Normative References
7.2. Informative References 7.2. Informative References
Appendix A. Changes to RFC 5316 Appendix A. Changes to RFC 5316
Acknowledgements Acknowledgements
Authors' Addresses Authors' Addresses
1. Introduction 1. Introduction
skipping to change at line 119 skipping to change at line 119
Requirements for establishing Multiprotocol Label Switching (MPLS) TE Requirements for establishing Multiprotocol Label Switching (MPLS) TE
Label Switched Paths (LSPs) that cross multiple Autonomous Systems Label Switched Paths (LSPs) that cross multiple Autonomous Systems
(ASes) are described in [RFC4216]. As described in [RFC4216], a (ASes) are described in [RFC4216]. As described in [RFC4216], a
method SHOULD provide the ability to compute a path spanning multiple method SHOULD provide the ability to compute a path spanning multiple
ASes. So a path computation entity that may be the head-end Label ASes. So a path computation entity that may be the head-end Label
Switching Router (LSR), an AS Border Router (ASBR), or a Path Switching Router (LSR), an AS Border Router (ASBR), or a Path
Computation Element (PCE) [RFC4655] needs to know the TE information Computation Element (PCE) [RFC4655] needs to know the TE information
not only of the links within an AS but also of the links that connect not only of the links within an AS but also of the links that connect
to other ASes. to other ASes.
In this document, the inter-AS reachability TLV is defined to In this document, the Inter-AS Reachability Information TLV is
advertise inter-AS TE information, and four sub-TLVs are defined for defined to advertise inter-AS TE information, and four sub-TLVs are
inclusion in the inter-AS reachability TLV to carry the information defined for inclusion in the Inter-AS Reachability Information TLV to
about the remote AS number, remote ASBR ID, and IPv6 Local ASBR ID. carry the information about the Remote AS Number, Remote ASBR
The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for Identifier, and IPv6 Local ASBR Identifier. The sub-TLVs defined in
inclusion in the extended IS reachability TLV for describing the TE [RFC5305], [RFC6119], and other documents for inclusion in the
properties of a TE link are applicable to be included in the Inter-AS extended IS reachability TLV for describing the TE properties of a TE
Reachability TLV for describing the TE properties of an inter-AS TE link are applicable to be included in the Inter-AS Reachability
Information TLV for describing the TE properties of an inter-AS TE
link as well. Also, two more sub-TLVs are defined for inclusion in link as well. Also, two more sub-TLVs are defined for inclusion in
the IS-IS Router CAPABILITY TLV to carry the TE Router ID when the TE the IS-IS Router CAPABILITY TLV to carry the TE Router ID when the TE
Router ID is needed to reach all routers within an entire IS-IS Router ID is needed to reach all routers within an entire IS-IS
routing domain. The extensions are equally applicable to IPv4 and routing domain. The extensions are equally applicable to IPv4 and
IPv6 as identical extensions to [RFC5305] and [RFC6119]. Detailed IPv6 as identical extensions to [RFC5305] and [RFC6119]. Detailed
definitions and procedures are discussed in the following sections. definitions and procedures are discussed in the following sections.
This document does not propose or define any mechanisms to advertise This document does not propose or define any mechanisms to advertise
any other extra-AS TE information within IS-IS. See Section 2.1 for any other extra-AS TE information within IS-IS. See Section 2.1 for
a full list of non-objectives for this work. a full list of non-objectives for this work.
skipping to change at line 329 skipping to change at line 330
3. Extensions to IS-IS TE 3. Extensions to IS-IS TE
Note that this document does not define mechanisms for distribution Note that this document does not define mechanisms for distribution
of TE information from one AS to another, does not distribute any of TE information from one AS to another, does not distribute any
form of TE reachability information for destinations outside the AS, form of TE reachability information for destinations outside the AS,
does not change the PCE architecture or usage, does not suggest or does not change the PCE architecture or usage, does not suggest or
recommend any form of TE aggregation, and does not feed private recommend any form of TE aggregation, and does not feed private
information between ASes. See Section 2.1. information between ASes. See Section 2.1.
In this document, the inter-AS reachability TLV is defined for the In this document, the Inter-AS Reachability Information TLV is
advertisement of inter-AS TE links. Four sub-TLVs are also defined defined for the advertisement of inter-AS TE links. Four sub-TLVs
for inclusion in the inter-AS reachability TLV to carry the are also defined for inclusion in the Inter-AS Reachability
information about the neighboring AS number, the remote ASBR ID, and Information TLV to carry the information about the neighboring AS
IPv6 Local ASBR ID of an inter-AS link. The sub-TLVs defined in number, the Remote ASBR Identifier, and IPv6 Local ASBR Identifier of
[RFC5305], [RFC6119], and other documents for inclusion in the an inter-AS link. The sub-TLVs defined in [RFC5305], [RFC6119], and
extended IS reachability TLV are applicable to be included in the other documents for inclusion in the extended IS reachability TLV are
inter-AS reachability TLV for the advertisement of inter-AS TE links. applicable to be included in the Inter-AS Reachability Information
TLV for the advertisement of inter-AS TE links.
This document also defines two sub-TLVs for inclusion in the IS-IS This document also defines two sub-TLVs for inclusion in the IS-IS
Router CAPABILITY TLV to carry the TE Router ID when the TE Router ID Router CAPABILITY TLV to carry the TE Router ID when the TE Router ID
is needed to reach all routers within an entire IS-IS routing domain. is needed to reach all routers within an entire IS-IS routing domain.
While some of the TE information of an inter-AS TE link may be While some of the TE information of an inter-AS TE link may be
available within the AS from other protocols, in order to avoid any available within the AS from other protocols, in order to avoid any
dependency on where such protocols are processed, this mechanism dependency on where such protocols are processed, this mechanism
carries all the information needed for the required TE operations. carries all the information needed for the required TE operations.
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address meets the requirements specified above. address meets the requirements specified above.
When advertising an IPv6 address as a TE Router ID, if the IPv6 TE When advertising an IPv6 address as a TE Router ID, if the IPv6 TE
Router ID TLV [RFC6119] is being advertised, then the address SHOULD Router ID TLV [RFC6119] is being advertised, then the address SHOULD
be identical to the address in the IPv6 TE Router ID TLV. The TE be identical to the address in the IPv6 TE Router ID TLV. The TE
Router ID MAY be identical to a non-link-local IPv6 Interface Address Router ID MAY be identical to a non-link-local IPv6 Interface Address
advertised by the originating IS in a Link State PDU using the IPv6 advertised by the originating IS in a Link State PDU using the IPv6
Interface Address TLV [RFC5308] so long as the address meets the Interface Address TLV [RFC5308] so long as the address meets the
requirements specified above. requirements specified above.
3.2. Inter-AS Reachability TLV 3.2. Inter-AS Reachability Information TLV
The inter-AS reachability TLV has type 141 (see Section 6.1) and The Inter-AS Reachability Information TLV has type 141 (see
contains a data structure consisting of: Section 6.1) and contains a data structure consisting of:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID (4 octets) | | Router ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Default Metric | (3 octets) | Default Metric | (3 octets)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | (1 octet) | Flags | (1 octet)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
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Flags consists of the following: Flags consists of the following:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|S|D| Rsvd | |S|D| Rsvd |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
where: where:
S bit: If the S bit is set(1), the Inter-AS Reachability TLV MUST be S bit: If the S bit is set(1), the Inter-AS Reachability Information
flooded across the entire routing domain. If the S bit is not TLV MUST be flooded across the entire routing domain. If the S
set(0), the TLV MUST NOT be leaked between levels. This bit MUST bit is not set(0), the TLV MUST NOT be leaked between levels.
NOT be altered during the TLV leaking. This bit MUST NOT be altered during the TLV leaking.
D bit: When the Inter-AS Reachability TLV is leaked from Level 2 D bit: When the Inter-AS Reachability Information TLV is leaked from
(L2) to Level 1 (L1), the D bit MUST be set. Otherwise, this bit Level 2 (L2) to Level 1 (L1), the D bit MUST be set. Otherwise,
MUST be clear. Inter-AS Reachability TLVs with the D bit set MUST this bit MUST be clear. Inter-AS Reachability Information TLVs
NOT be leaked from Level 1 to Level 2. This is to prevent TLV with the D bit set MUST NOT be leaked from Level 1 to Level 2.
looping. This is to prevent TLV looping.
Reserved (Rsvd): Reserved bits MUST be zero when originated and Reserved (Rsvd): Reserved bits MUST be zero when originated and
ignored when received. ignored when received.
Compared to the extended IS reachability TLV, which is defined in Compared to the extended IS reachability TLV, which is defined in
[RFC5305], the inter-AS reachability TLV replaces the "7 octets of [RFC5305], the Inter-AS Reachability Information TLV replaces the "7
System ID and Pseudonode Number" field with a "4 octets of Router ID" octets of System ID and Pseudonode Number" field with a "4 octets of
field and introduces an extra "control information" field, which Router ID" field and introduces an extra "control information" field,
consists of a flooding-scope bit (S bit), an up/down bit (D bit), and which consists of a flooding-scope bit (S bit), an up/down bit (D
6 reserved bits. bit), and 6 reserved bits.
The Router ID field of the inter-AS reachability TLV is 4 octets in The Router ID field of the Inter-AS Reachability Information TLV is 4
length and has a value as defined in Section 3.1. If the originating octets in length and has a value as defined in Section 3.1. If the
node does not support IPv4, then the reserved value 0.0.0.0 MUST be originating node does not support IPv4, then the reserved value
used in the Router ID field, and the IPv6 Router ID sub-TLV MUST be 0.0.0.0 MUST be used in the Router ID field, and the IPv6 Router ID
present in the inter-AS reachability TLV. The Router ID could be sub-TLV MUST be present in the Inter-AS Reachability Information TLV.
used to indicate the source of the inter-AS reachability TLV. The Router ID could be used to indicate the source of the Inter-AS
Reachability Information TLV.
The flooding procedures for the inter-AS reachability TLV are The flooding procedures for the Inter-AS Reachability Information TLV
identical to the flooding procedures for the GENINFO TLV, which are are identical to the flooding procedures for the GENINFO TLV, which
defined in Section 4 of [RFC6823]. These procedures have been are defined in Section 4 of [RFC6823]. These procedures have been
previously discussed in [RFC7981]. The flooding-scope bit (S bit) previously discussed in [RFC7981]. The flooding-scope bit (S bit)
SHOULD be set to 0 if the flooding scope is to be limited to within SHOULD be set to 0 if the flooding scope is to be limited to within
the single IGP area to which the ASBR belongs. It MAY be set to 1 if the single IGP area to which the ASBR belongs. It MAY be set to 1 if
the information is intended to reach all routers (including area the information is intended to reach all routers (including area
border routers, ASBRs, and PCEs) in the entire IS-IS routing domain. border routers, ASBRs, and PCEs) in the entire IS-IS routing domain.
The choice between the use of 0 or 1 is an AS-wide policy choice, and The choice between the use of 0 or 1 is an AS-wide policy choice, and
configuration control SHOULD be provided in ASBR implementations that configuration control SHOULD be provided in ASBR implementations that
support the advertisement of inter-AS TE links. support the advertisement of inter-AS TE links.
The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for The sub-TLVs defined in [RFC5305], [RFC6119], and other documents for
describing the TE properties of a TE link are also applicable to the describing the TE properties of a TE link are also applicable to the
inter-AS reachability TLV for describing the TE properties of an Inter-AS Reachability Information TLV for describing the TE
inter-AS TE link. Apart from these sub-TLVs, four sub-TLVs are properties of an inter-AS TE link. Apart from these sub-TLVs, four
defined for inclusion in the inter-AS reachability TLV defined in sub-TLVs are defined for inclusion in the Inter-AS Reachability
this document: Information TLV defined in this document:
+==============+========+=============================+ +==============+========+=============================+
| Sub-TLV type | Length | Name | | Sub-TLV type | Length | Name |
+==============+========+=============================+ +==============+========+=============================+
| 24 | 4 | remote AS number | | 24 | 4 | Remote AS Number |
+--------------+--------+-----------------------------+ +--------------+--------+-----------------------------+
| 25 | 4 | IPv4 remote ASBR identifier | | 25 | 4 | IPv4 Remote ASBR Identifier |
+--------------+--------+-----------------------------+ +--------------+--------+-----------------------------+
| 26 | 16 | IPv6 remote ASBR identifier | | 26 | 16 | IPv6 Remote ASBR Identifier |
+--------------+--------+-----------------------------+ +--------------+--------+-----------------------------+
| 45 | 16 | IPv6 local ASBR identifier | | 45 | 16 | IPv6 Local ASBR Identifier |
+--------------+--------+-----------------------------+ +--------------+--------+-----------------------------+
Table 1 Table 1
Detailed definitions of these four sub-TLVs are described in Sections Detailed definitions of these four sub-TLVs are described in Sections
3.4.1, 3.4.2, 3.4.3, and 3.4.4. 3.4.1, 3.4.2, 3.4.3, and 3.4.4.
3.3. TE Router ID 3.3. TE Router ID
The Traffic Engineering router ID TLV and IPv6 TE Router ID TLV, The Traffic Engineering router ID TLV and IPv6 TE Router ID TLV,
which are defined in [RFC5305] and [RFC6119], respectively, only have which are defined in [RFC5305] and [RFC6119], respectively, only have
area flooding scope. When performing inter-AS TE, the TE Router ID area flooding scope. When performing inter-AS TE, the TE Router ID
MAY be needed to reach all routers within an entire IS-IS routing MAY be needed to reach all routers within an entire IS-IS routing
domain, and it MUST have the same flooding scope as the Inter-AS domain, and it MUST have the same flooding scope as the Inter-AS
Reachability TLV does. Reachability Information TLV does.
[RFC7981] defines a generic advertisement mechanism for IS-IS, which [RFC7981] defines a generic advertisement mechanism for IS-IS, which
allows a router to advertise its capabilities within an IS-IS area or allows a router to advertise its capabilities within an IS-IS area or
an entire IS-IS routing domain. [RFC7981] also points out that the an entire IS-IS routing domain. [RFC7981] also points out that the
TE Router ID is a candidate to be carried in the IS-IS Router TE Router ID is a candidate to be carried in the IS-IS Router
CAPABILITY TLV when performing inter-area TE. CAPABILITY TLV when performing inter-area TE.
This document uses such mechanism for TE Router ID advertisement when This document uses such mechanism for TE Router ID advertisement when
the TE Router ID is needed to reach all routers within an entire IS- the TE Router ID is needed to reach all routers within an entire IS-
IS routing domain. Two sub-TLVs are defined for inclusion in the IS- IS routing domain. Two sub-TLVs are defined for inclusion in the IS-
skipping to change at line 497 skipping to change at line 500
| 11 | 4 | IPv4 TE Router ID | | 11 | 4 | IPv4 TE Router ID |
+--------------+--------+-------------------+ +--------------+--------+-------------------+
| 12 | 16 | IPv6 TE Router ID | | 12 | 16 | IPv6 TE Router ID |
+--------------+--------+-------------------+ +--------------+--------+-------------------+
Table 2 Table 2
Detailed definitions of these sub-TLVs are described in Sections Detailed definitions of these sub-TLVs are described in Sections
3.4.1 and 3.4.2. 3.4.1 and 3.4.2.
3.4. Sub-TLVs for Inter-AS Reachability TLV 3.4. Sub-TLVs for Inter-AS Reachability Information TLV
3.4.1. Remote AS Number Sub-TLV 3.4.1. Remote AS Number Sub-TLV
The remote AS number sub-TLV is defined for inclusion in the inter-AS The Remote AS Number sub-TLV is defined for inclusion in the Inter-AS
reachability TLV when advertising inter-AS links. The remote AS Reachability Information TLV when advertising inter-AS links. The
number sub-TLV specifies the AS number of the neighboring AS to which Remote AS Number sub-TLV specifies the AS number of the neighboring
the advertised link connects. AS to which the advertised link connects.
The remote AS number sub-TLV is TLV type 24 (see Section 6.2) and is The Remote AS Number sub-TLV is TLV type 24 (see Section 6.2) and is
4 octets in length. The format is as follows: 4 octets in length. The format is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote AS Number | | Remote AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Remote AS Number field has 4 octets. When only 2 octets are used The Remote AS Number field has 4 octets. When only 2 octets are used
for the AS number, the left (high-order) 2 octets MUST be set to 0. for the AS number, the left (high-order) 2 octets MUST be set to 0.
The remote AS number sub-TLV MUST be included when a router The Remote AS Number sub-TLV MUST be included when a router
advertises an inter-AS TE link. advertises an inter-AS TE link.
3.4.2. IPv4 Remote ASBR ID Sub-TLV 3.4.2. IPv4 Remote ASBR Identifier Sub-TLV
The IPv4 remote ASBR ID sub-TLV is defined for inclusion in the The IPv4 Remote ASBR Identifier sub-TLV is defined for inclusion in
inter-AS reachability TLV when advertising inter-AS links. The IPv4 the Inter-AS Reachability Information TLV when advertising inter-AS
remote ASBR ID sub-TLV specifies the IPv4 identifier of the remote links. The IPv4 Remote ASBR Identifier sub-TLV specifies the IPv4
ASBR to which the advertised inter-AS link connects. The value identifier of the remote ASBR to which the advertised inter-AS link
advertised is selected as defined in Section 3.1. connects. The value advertised is selected as defined in
Section 3.1.
The IPv4 remote ASBR ID sub-TLV is TLV type 25 (see Section 6.2) and The IPv4 Remote ASBR Identifier sub-TLV is TLV type 25 (see
is 4 octets in length. The format of the IPv4 remote ASBR ID sub-TLV Section 6.2) and is 4 octets in length. The format of the IPv4
is as follows: Remote ASBR Identifier sub-TLV is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The IPv4 remote ASBR ID sub-TLV MUST be included if the neighboring The IPv4 Remote ASBR Identifier sub-TLV MUST be included if the
ASBR has an IPv4 address. If the neighboring ASBR does not have an neighboring ASBR has an IPv4 address. If the neighboring ASBR does
IPv4 address, the IPv6 remote ASBR ID sub-TLV MUST be included not have an IPv4 address, the IPv6 Remote ASBR Identifier sub-TLV
instead. An IPv4 remote ASBR ID sub-TLV and IPv6 remote ASBR ID sub- MUST be included instead. An IPv4 Remote ASBR Identifier sub-TLV and
TLV MAY both be present in an extended IS reachability TLV. IPv6 Remote ASBR Identifier sub-TLV MAY both be present in an
extended IS reachability TLV.
3.4.3. IPv6 Remote ASBR ID Sub-TLV 3.4.3. IPv6 Remote ASBR Identifier Sub-TLV
The IPv6 remote ASBR ID sub-TLV is defined for inclusion in the The IPv6 Remote ASBR Identifier sub-TLV is defined for inclusion in
inter-AS reachability TLV when advertising inter-AS links. The IPv6 the Inter-AS Reachability Information TLV when advertising inter-AS
remote ASBR ID sub-TLV specifies the IPv6 identifier of the remote links. The IPv6 Remote ASBR Identifier sub-TLV specifies the IPv6
ASBR to which the advertised inter-AS link connects. The value identifier of the remote ASBR to which the advertised inter-AS link
advertised is selected as defined in Section 3.1. connects. The value advertised is selected as defined in
Section 3.1.
The IPv6 remote ASBR ID sub-TLV is TLV type 26 (see Section 6.2) and The IPv6 Remote ASBR Identifier sub-TLV is TLV type 26 (see
is 16 octets in length. The format of the IPv6 remote ASBR ID sub- Section 6.2) and is 16 octets in length. The format of the IPv6
TLV is as follows: Remote ASBR Identifier sub-TLV is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The IPv6 remote ASBR ID sub-TLV MUST be included if the neighboring The IPv6 Remote ASBR Identifier sub-TLV MUST be included if the
ASBR has an IPv6 address. If the neighboring ASBR does not have an neighboring ASBR has an IPv6 address. If the neighboring ASBR does
IPv6 address, the IPv4 remote ASBR ID sub-TLV MUST be included not have an IPv6 address, the IPv4 Remote ASBR Identifier sub-TLV
instead. An IPv4 remote ASBR ID sub-TLV and IPv6 remote ASBR ID sub- MUST be included instead. An IPv4 Remote ASBR Identifier sub-TLV and
TLV MAY both be present in an extended IS reachability TLV. IPv6 Remote ASBR Identifier sub-TLV MAY both be present in an
extended IS reachability TLV.
3.4.4. IPv6 Local ASBR ID Sub-TLV 3.4.4. IPv6 Local ASBR Identifier Sub-TLV
The IPv6 Local ASBR ID sub-TLV is defined for inclusion in the inter- The IPv6 Local ASBR Identifier sub-TLV is defined for inclusion in
AS reachability TLV when advertising inter-AS links. The IPv6 Local the Inter-AS Reachability Information TLV when advertising inter-AS
ASBR ID sub-TLV specifies the IPv6 identifier of the remote ASBR to links. The IPv6 Local ASBR Identifier sub-TLV specifies the IPv6
which the advertised inter-AS link connects. The value advertised is identifier of the remote ASBR to which the advertised inter-AS link
selected as defined in Section 3.1. connects. The value advertised is selected as defined in
Section 3.1.
The IPv6 Local ASBR ID sub-TLV is TLV type 45 (see Section 6.2) and The IPv6 Local ASBR Identifier sub-TLV is TLV type 45 (see
is 16 octets in length. The format of the IPv6 Local ASBR ID sub-TLV Section 6.2) and is 16 octets in length. The format of the IPv6
is as follows: Local ASBR Identifier sub-TLV is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID | | Local ASBR Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local ASBR ID (continued) | | Local ASBR Identifier (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If the originating node does not support IPv4, the IPv6 Local ASBR ID If the originating node does not support IPv4, the IPv6 Local ASBR
sub-TLV MUST be present in the inter-AS reachability TLV. Inter-AS Identifier sub-TLV MUST be present in the Inter-AS Reachability
reachability TLVs that have a Router ID of 0.0.0.0 and do not have Information TLV. Inter-AS Reachability Information TLVs that have a
the IPv6 Local ASBR ID sub-TLV present MUST be ignored. Router ID of 0.0.0.0 and do not have the IPv6 Local ASBR Identifier
sub-TLV present MUST be ignored.
3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV 3.5. Sub-TLVs for IS-IS Router CAPABILITY TLV
3.5.1. IPv4 TE Router ID Sub-TLV 3.5.1. IPv4 TE Router ID Sub-TLV
The IPv4 TE Router ID sub-TLV is TLV type 11 (see Section 6.3) and is The IPv4 TE Router ID sub-TLV is TLV type 11 (see Section 6.3) and is
4 octets in length. The format of the IPv4 TE Router ID sub-TLV is 4 octets in length. The format of the IPv4 TE Router ID sub-TLV is
as follows: as follows:
0 1 2 3 0 1 2 3
skipping to change at line 684 skipping to change at line 693
SHOULD withdraw the advertisement. When there are changes to the TE SHOULD withdraw the advertisement. When there are changes to the TE
parameters for the link (for example, when the available bandwidth parameters for the link (for example, when the available bandwidth
changes), the ASBR SHOULD re-advertise the link but MUST take changes), the ASBR SHOULD re-advertise the link but MUST take
precautions against excessive re-advertisements. precautions against excessive re-advertisements.
Hellos MUST NOT be exchanged over the inter-AS link, and Hellos MUST NOT be exchanged over the inter-AS link, and
consequently, an IS-IS adjacency MUST NOT be formed. consequently, an IS-IS adjacency MUST NOT be formed.
The information advertised comes from the ASBR's knowledge of the TE The information advertised comes from the ASBR's knowledge of the TE
capabilities of the link, the ASBR's knowledge of the current status capabilities of the link, the ASBR's knowledge of the current status
and usage of the link, and configuration at the ASBR of the remote AS and usage of the link, and configuration at the ASBR of the Remote AS
number and remote ASBR TE Router ID. Number and remote ASBR TE Router ID.
Legacy routers receiving an advertisement for an inter-AS TE link are Legacy routers receiving an advertisement for an inter-AS TE link are
able to ignore it because they do not know the TLV and sub-TLVs that able to ignore it because they do not know the TLV and sub-TLVs that
are defined in Section 3 of this document. They will continue to are defined in Section 3 of this document. They will continue to
flood the LSP but will not attempt to use the information received. flood the LSP but will not attempt to use the information received.
In the current operation of IS-IS TE, the LSRs at each end of a TE In the current operation of IS-IS TE, the LSRs at each end of a TE
link emit LSPs describing the link. The databases in the LSRs then link emit LSPs describing the link. The databases in the LSRs then
have two entries (one locally generated, the other from the peer) have two entries (one locally generated, the other from the peer)
that describe the different 'directions' of the link. This enables that describe the different 'directions' of the link. This enables
skipping to change at line 716 skipping to change at line 725
properties into the TE database. properties into the TE database.
This is achieved by the ASBR advertising, internally to its AS, This is achieved by the ASBR advertising, internally to its AS,
information about both directions of the TE link to the next AS. The information about both directions of the TE link to the next AS. The
ASBR will normally generate an LSP describing its own side of a link; ASBR will normally generate an LSP describing its own side of a link;
here, we have it 'proxy' for the ASBR at the edge of the other AS and here, we have it 'proxy' for the ASBR at the edge of the other AS and
generate an additional LSP that describes that device's 'view' of the generate an additional LSP that describes that device's 'view' of the
link. link.
Only some essential TE information for the link needs to be Only some essential TE information for the link needs to be
advertised, i.e., the Interface Address, the remote AS number, and advertised, i.e., the Interface Address, the Remote AS Number, and
the remote ASBR ID of an inter-AS TE link. the Remote ASBR Identifier of an inter-AS TE link.
Routers or PCEs that are capable of processing advertisements of Routers or PCEs that are capable of processing advertisements of
inter-AS TE links SHOULD NOT use such links to compute paths that inter-AS TE links SHOULD NOT use such links to compute paths that
exit an AS to a remote ASBR and then immediately re-enter the AS exit an AS to a remote ASBR and then immediately re-enter the AS
through another TE link. Such paths would constitute extremely rare through another TE link. Such paths would constitute extremely rare
occurrences and SHOULD NOT be allowed except as the result of occurrences and SHOULD NOT be allowed except as the result of
specific policy configurations at the router or PCE computing the specific policy configurations at the router or PCE computing the
path. path.
4.1. Origin of Proxied TE Information 4.1. Origin of Proxied TE Information
skipping to change at line 760 skipping to change at line 769
existing IS-IS security mechanisms (e.g., using the cleartext existing IS-IS security mechanisms (e.g., using the cleartext
passwords or Hashed Message Authentication Codes, which are defined passwords or Hashed Message Authentication Codes, which are defined
in [RFC1195], [RFC5304], and [RFC5310] separately). in [RFC1195], [RFC5304], and [RFC5310] separately).
There is no exchange of information between ASes and no change to the There is no exchange of information between ASes and no change to the
IS-IS security relationship between the ASes. In particular, since IS-IS security relationship between the ASes. In particular, since
no IS-IS adjacency is formed on the inter-AS links, there is no no IS-IS adjacency is formed on the inter-AS links, there is no
requirement for IS-IS security between the ASes. requirement for IS-IS security between the ASes.
Some of the information included in these advertisements (e.g., the Some of the information included in these advertisements (e.g., the
remote AS number and the remote ASBR ID) is obtained manually from a Remote AS Number and the Remote ASBR Identifier) is obtained manually
neighboring administration as part of a commercial relationship. The from a neighboring administration as part of a commercial
source and content of this information should be carefully checked relationship. The source and content of this information should be
before it is entered as configuration information at the ASBR carefully checked before it is entered as configuration information
responsible for advertising the inter-AS TE links. at the ASBR responsible for advertising the inter-AS TE links.
It is worth noting that, in the scenario we are considering, a Border It is worth noting that, in the scenario we are considering, a Border
Gateway Protocol (BGP) peering may exist between the two ASBRs and Gateway Protocol (BGP) peering may exist between the two ASBRs and
that this could be used to detect inconsistencies in configuration that this could be used to detect inconsistencies in configuration
(e.g., the administration that originally supplied the information (e.g., the administration that originally supplied the information
may provide incorrect information, or some manual misconfigurations may provide incorrect information, or some manual misconfigurations
or mistakes may be made by the operators). For example, if a or mistakes may be made by the operators). For example, if a
different remote AS number is received in a BGP OPEN [RFC4271] from different Remote AS Number is received in a BGP OPEN [RFC4271] from
that locally configured to IS-IS TE, as we describe here, then local that locally configured to IS-IS TE, as we describe here, then local
policy SHOULD be applied to determine whether to alert the operator policy SHOULD be applied to determine whether to alert the operator
to a potential misconfiguration or to suppress the IS-IS to a potential misconfiguration or to suppress the IS-IS
advertisement of the inter-AS TE link. Advertisement of incorrect advertisement of the inter-AS TE link. Advertisement of incorrect
information could result in an inter-AS TE LSP that traverses an information could result in an inter-AS TE LSP that traverses an
unintended AS. Note further that, if BGP is used to exchange TE unintended AS. Note further that, if BGP is used to exchange TE
information as described in Section 4.1, the inter-AS BGP session information as described in Section 4.1, the inter-AS BGP session
SHOULD be secured using mechanisms such as described in [RFC5925] to SHOULD be secured using mechanisms such as described in [RFC5925] to
provide authentication and integrity checks. provide authentication and integrity checks.
For a discussion of general security considerations for IS-IS, see For a discussion of general security considerations for IS-IS, see
[RFC5304]. [RFC5304].
6. IANA Considerations 6. IANA Considerations
6.1. Inter-AS Reachability TLV 6.1. Inter-AS Reachability Information TLV
IANA has registered the following IS-IS TLV type, described in IANA has registered the following IS-IS TLV type, described in
Section 3.1, in the "IS-IS Top-Level TLV Codepoints" registry: Section 3.1, in the "IS-IS Top-Level TLV Codepoints" registry:
+=======+==============+=====+=====+=====+=======+===========+ +=======+==============+=====+=====+=====+=======+===========+
| Value | Name | IIH | LSP | SNP | Purge | Reference | | Value | Name | IIH | LSP | SNP | Purge | Reference |
+=======+==============+=====+=====+=====+=======+===========+ +=======+==============+=====+=====+=====+=======+===========+
| 141 | inter-AS | n | y | n | n | RFC 9346 | | 141 | Inter-AS | n | y | n | n | RFC 9346 |
| | reachability | | | | | | | | Reachability | | | | | |
| | information | | | | | | | | Information | | | | | |
+-------+--------------+-----+-----+-----+-------+-----------+ +-------+--------------+-----+-----+-----+-------+-----------+
Table 3 Table 3
6.2. Sub-TLVs for the Inter-AS Reachability TLV 6.2. Sub-TLVs for the Inter-AS Reachability Information TLV
IANA has registered the following sub-TLV types of top-level TLV 141 IANA has registered the following sub-TLV types of top-level TLV 141
(see Section 6.1) in the "IS-IS Sub-TLVs for TLVs Advertising (see Section 6.1) in the "IS-IS Sub-TLVs for TLVs Advertising
Neighbor Information" registry. These sub-TLVs are described in Neighbor Information" registry. These sub-TLVs are described in
Sections 3.4.1, 3.4.2, 3.4.3, and 3.4.4. Sections 3.4.1, 3.4.2, 3.4.3, and 3.4.4.
+=======+=============+====+====+====+=====+=====+=====+===========+ +=======+=============+====+====+====+=====+=====+=====+===========+
| Value | Description | 22 | 23 | 25 | 141 | 222 | 223 | Reference | | Value | Description | 22 | 23 | 25 | 141 | 222 | 223 | Reference |
+=======+=============+====+====+====+=====+=====+=====+===========+ +=======+=============+====+====+====+=====+=====+=====+===========+
| 24 | remote AS | n | n | n | y | n | n | RFC 9346 | | 24 | Remote AS | n | n | n | y | n | n | RFC 9346 |
| | number | | | | | | | | | | Number | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+ +-------+-------------+----+----+----+-----+-----+-----+-----------+
| 25 | IPv4 remote | n | n | n | y | n | n | RFC 9346 | | 25 | IPv4 Remote | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | | | | ASBR | | | | | | | |
| | identifier | | | | | | | | | | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+ +-------+-------------+----+----+----+-----+-----+-----+-----------+
| 26 | IPv6 remote | n | n | n | y | n | n | RFC 9346 | | 26 | IPv6 Remote | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | | | | ASBR | | | | | | | |
| | identifier | | | | | | | | | | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+ +-------+-------------+----+----+----+-----+-----+-----+-----------+
| 45 | IPv6 local | n | n | n | y | n | n | RFC 9346 | | 45 | IPv6 Local | n | n | n | y | n | n | RFC 9346 |
| | ASBR | | | | | | | | | | ASBR | | | | | | | |
| | identifier | | | | | | | | | | Identifier | | | | | | | |
+-------+-------------+----+----+----+-----+-----+-----+-----------+ +-------+-------------+----+----+----+-----+-----+-----+-----------+
Table 4 Table 4
As described in Section 3.1, the sub-TLVs that are defined in As described in Section 3.1, the sub-TLVs that are defined in
[RFC5305], [RFC6119], and other documents for describing the TE [RFC5305], [RFC6119], and other documents for describing the TE
properties of a TE link are applicable to describe an inter-AS TE properties of a TE link are applicable to describe an inter-AS TE
link and MAY be included in the inter-AS reachability TLV when link and MAY be included in the Inter-AS Reachability Information TLV
adverting inter-AS TE links. when adverting inter-AS TE links.
6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV 6.3. Sub-TLVs for the IS-IS Router CAPABILITY TLV
IANA has registered the following sub-TLV types of top-level TLV 242 IANA has registered the following sub-TLV types of top-level TLV 242
(see [RFC7981]) in the "IS-IS Sub-TLVs for IS-IS Router CAPABILITY (see [RFC7981]) in the "IS-IS Sub-TLVs for IS-IS Router CAPABILITY
TLV" registry. These sub-TLVs are described in Sections 3.4.1 and TLV" registry. These sub-TLVs are described in Sections 3.4.1 and
3.4.2. 3.4.2.
+======+===================+===========+ +======+===================+===========+
| Type | Description | Reference | | Type | Description | Reference |
skipping to change at line 858 skipping to change at line 867
+------+-------------------+-----------+ +------+-------------------+-----------+
| 12 | IPv6 TE Router ID | RFC 9346 | | 12 | IPv6 TE Router ID | RFC 9346 |
+------+-------------------+-----------+ +------+-------------------+-----------+
Table 5 Table 5
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC1195] Callon, R. and RFC Publisher, "Use of OSI IS-IS for [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
routing in TCP/IP and dual environments", RFC 1195, dual environments", RFC 1195, DOI 10.17487/RFC1195,
DOI 10.17487/RFC1195, December 1990, December 1990, <https://www.rfc-editor.org/info/rfc1195>.
<https://www.rfc-editor.org/info/rfc1195>.
[RFC2119] Bradner, S. and RFC Publisher, "Key words for use in RFCs [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
to Indicate Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., Hares, S., Ed., and RFC [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Publisher, "A Border Gateway Protocol 4 (BGP-4)", Border Gateway Protocol 4 (BGP-4)", RFC 4271,
RFC 4271, DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[RFC5305] Li, T., Smit, H., and RFC Publisher, "IS-IS Extensions for [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, Engineering", RFC 5305, DOI 10.17487/RFC5305, October
October 2008, <https://www.rfc-editor.org/info/rfc5305>. 2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5308] Hopps, C. and RFC Publisher, "Routing IPv6 with IS-IS", [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
RFC 5308, DOI 10.17487/RFC5308, October 2008, DOI 10.17487/RFC5308, October 2008,
<https://www.rfc-editor.org/info/rfc5308>. <https://www.rfc-editor.org/info/rfc5308>.
[RFC5925] Touch, J., Mankin, A., Bonica, R., and RFC Publisher, "The [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
TCP Authentication Option", RFC 5925, Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
DOI 10.17487/RFC5925, June 2010, June 2010, <https://www.rfc-editor.org/info/rfc5925>.
<https://www.rfc-editor.org/info/rfc5925>.
[RFC6119] Harrison, J., Berger, J., Bartlett, M., and RFC Publisher, [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
"IPv6 Traffic Engineering in IS-IS", RFC 6119, Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119,
DOI 10.17487/RFC6119, February 2011, February 2011, <https://www.rfc-editor.org/info/rfc6119>.
<https://www.rfc-editor.org/info/rfc6119>.
[RFC7981] Ginsberg, L., Previdi, S., Chen, M., and RFC Publisher, [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
"IS-IS Extensions for Advertising Router Information", for Advertising Router Information", RFC 7981,
RFC 7981, DOI 10.17487/RFC7981, October 2016, DOI 10.17487/RFC7981, October 2016,
<https://www.rfc-editor.org/info/rfc7981>. <https://www.rfc-editor.org/info/rfc7981>.
[RFC8174] Leiba, B. and RFC Publisher, "Ambiguity of Uppercase vs [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
DOI 10.17487/RFC8174, May 2017, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
<https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References 7.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
Swallow, G., and RFC Publisher, "RSVP-TE: Extensions to and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
December 2001, <https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC4216] Zhang, R., Ed., Vasseur, J.-P., Ed., and RFC Publisher, [RFC4216] Zhang, R., Ed. and J.-P. Vasseur, Ed., "MPLS Inter-
"MPLS Inter-Autonomous System (AS) Traffic Engineering Autonomous System (AS) Traffic Engineering (TE)
(TE) Requirements", RFC 4216, DOI 10.17487/RFC4216, Requirements", RFC 4216, DOI 10.17487/RFC4216, November
November 2005, <https://www.rfc-editor.org/info/rfc4216>. 2005, <https://www.rfc-editor.org/info/rfc4216>.
[RFC4655] Farrel, A., Vasseur, J.-P., Ash, J., and RFC Publisher, "A [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Path Computation Element (PCE)-Based Architecture", Computation Element (PCE)-Based Architecture", RFC 4655,
RFC 4655, DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., Zhang, R., and RFC [RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Publisher, "A Per-Domain Path Computation Method for Per-Domain Path Computation Method for Establishing Inter-
Establishing Inter-Domain Traffic Engineering (TE) Label Domain Traffic Engineering (TE) Label Switched Paths
Switched Paths (LSPs)", RFC 5152, DOI 10.17487/RFC5152, (LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
February 2008, <https://www.rfc-editor.org/info/rfc5152>. <https://www.rfc-editor.org/info/rfc5152>.
[RFC5304] Li, T., Atkinson, R., and RFC Publisher, "IS-IS [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Cryptographic Authentication", RFC 5304, Authentication", RFC 5304, DOI 10.17487/RFC5304, October
DOI 10.17487/RFC5304, October 2008, 2008, <https://www.rfc-editor.org/info/rfc5304>.
<https://www.rfc-editor.org/info/rfc5304>.
[RFC5307] Kompella, K., Ed., Rekhter, Y., Ed., and RFC Publisher, [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
"IS-IS Extensions in Support of Generalized Multi-Protocol in Support of Generalized Multi-Protocol Label Switching
Label Switching (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
October 2008, <https://www.rfc-editor.org/info/rfc5307>. <https://www.rfc-editor.org/info/rfc5307>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
Fanto, M., and RFC Publisher, "IS-IS Generic Cryptographic and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>. 2009, <https://www.rfc-editor.org/info/rfc5310>.
[RFC5316] Chen, M., Zhang, R., Duan, X., and RFC Publisher, "ISIS [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Extensions in Support of Inter-Autonomous System (AS) MPLS Support of Inter-Autonomous System (AS) MPLS and GMPLS
and GMPLS Traffic Engineering", RFC 5316, Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
DOI 10.17487/RFC5316, December 2008, December 2008, <https://www.rfc-editor.org/info/rfc5316>.
<https://www.rfc-editor.org/info/rfc5316>.
[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., Le Roux, JL., and [RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux,
RFC Publisher, "A Backward-Recursive PCE-Based Computation "A Backward-Recursive PCE-Based Computation (BRPC)
(BRPC) Procedure to Compute Shortest Constrained Inter- Procedure to Compute Shortest Constrained Inter-Domain
Domain Traffic Engineering Label Switched Paths", Traffic Engineering Label Switched Paths", RFC 5441,
RFC 5441, DOI 10.17487/RFC5441, April 2009, DOI 10.17487/RFC5441, April 2009,
<https://www.rfc-editor.org/info/rfc5441>. <https://www.rfc-editor.org/info/rfc5441>.
[RFC6823] Ginsberg, L., Previdi, S., Shand, M., and RFC Publisher, [RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising
"Advertising Generic Information in IS-IS", RFC 6823, Generic Information in IS-IS", RFC 6823,
DOI 10.17487/RFC6823, December 2012, DOI 10.17487/RFC6823, December 2012,
<https://www.rfc-editor.org/info/rfc6823>. <https://www.rfc-editor.org/info/rfc6823>.
Appendix A. Changes to RFC 5316 Appendix A. Changes to RFC 5316
The following is a summary of the substantive changes this document The following is a summary of the substantive changes this document
makes to RFC 5316. Some editorial changes were also made. makes to RFC 5316. Some editorial changes were also made.
RFC 5316 only allowed a 32-bit Router ID in the fixed header of TLV RFC 5316 only allowed a 32-bit Router ID in the fixed header of TLV
141. This is problematic in an IPv6-only deployment where an IPv4 141. This is problematic in an IPv6-only deployment where an IPv4
skipping to change at line 975 skipping to change at line 978
1. The Router ID should be identical to the value advertised in the 1. The Router ID should be identical to the value advertised in the
Traffic Engineering router ID TLV (134) if available. Traffic Engineering router ID TLV (134) if available.
2. If no Traffic Engineering Router ID is assigned, the Router ID 2. If no Traffic Engineering Router ID is assigned, the Router ID
should be identical to an IP Interface Address [RFC1195] should be identical to an IP Interface Address [RFC1195]
advertised by the originating IS. advertised by the originating IS.
3. If the originating node does not support IPv4, then the reserved 3. If the originating node does not support IPv4, then the reserved
value 0.0.0.0 must be used in the Router ID field and the IPv6 value 0.0.0.0 must be used in the Router ID field and the IPv6
Local ASBR identifier sub-TLV must be present in the TLV. Local ASBR Identifier sub-TLV must be present in the TLV.
Acknowledgements Acknowledgements
In the previous version of this document [RFC5316], the authors In the previous version of this document [RFC5316], the authors
thanked Adrian Farrel, Jean-Louis Le Roux, Christian Hopps, and thanked Adrian Farrel, Jean-Louis Le Roux, Christian Hopps, and
Hannes Gredler for their review and comments. Hannes Gredler for their review and comments.
Authors' Addresses Authors' Addresses
Mach(Guoyi) Chen Mach(Guoyi) Chen
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