ISIS Extensions for Broadcast Inter-AS TE Link
draft-chen-isis-ias-lk-08
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Huaimo Chen , Mehmet Toy , Xufeng Liu , Lei Liu , Zhenqiang Li , Yi Yang | ||
| Last updated | 2022-01-10 | ||
| Stream | (None) | ||
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draft-chen-isis-ias-lk-08
ISIS Working Group H. Chen
Internet-Draft Futurewei
Intended status: Standards Track M. Toy
Expires: 14 July 2022 Verizon
X. Liu
Volta Networks
L. Liu
Fujitsu
Z. Li
China Mobile
Y. Yang
IBM
10 January 2022
ISIS Extensions for Broadcast Inter-AS TE Link
draft-chen-isis-ias-lk-08
Abstract
This document presents extensions to the ISIS protocol for
advertising broadcast inter-AS Traffic Engineering (TE) links.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 14 July 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Information on Inter-AS TE Link . . . . . . . . . . . . . . . 3
4. Extensions to ISIS . . . . . . . . . . . . . . . . . . . . . 3
4.1. sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 3
4.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 4
4.2.1. ISIS Router Procedure . . . . . . . . . . . . . . . . 4
4.2.2. Super Node Procedure . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Connections among different Autonomous Systems (ASes) may be point-
to-point (P2P) links and broadcast links. For a P2P inter-AS TE
link, RFC 5316 defines a new TLV, the inter-AS reachability TLV, for
advertising the link.
It also defines three new sub-TLVs for inclusion in the inter-AS
reachability TLV to carry the information about the neighboring AS
number and the remote ASBR ID of an inter-AS link.
For a P2P inter-AS link, the information about its remote ASBR may be
configured. For a broadcast inter-AS link, no item configured
corresponds to the designated router (DR) of the link in ISIS. Since
no ISIS runs over any broadcast inter-AS link, no DR is selected. It
is hard to configure an item corresponding to the DR on a broadcast
link.
This document presents extensions to ISIS for advertising broadcast
inter-AS TE links through defining a new sub-TLV for a broadcast link
without configuring any item corresponding to the DR on the link.
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2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Information on Inter-AS TE Link
For a broadcast link connecting multiple ASBRs in a number of ASes,
on each of the ASBRs X, the following information about the link may
be obtained:
1) Link Type: Multi-access
2) Local IP address with mask length
3) Traffic engineering metric
4) Maximum bandwidth
5) Maximum reservable bandwidth
6) Unreserved bandwidth
7) Administrative group
8) SRLG
No remote IP address or item corresponding to the DR (i.e., DR's
interface address) may be obtained.
4. Extensions to ISIS
4.1. sub-TLVs
Two new sub-TLVs are defined. One is for local IPv4 address with
mask length; and the other is for local IPv6 address with mask
length.
The format of the sub-TLV for a local IPv4 address with mask length
is shown 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 (stTBD1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask Length |
+-+-+-+-+-+-+-+-+
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The IPv4 Address indicates the local IPv4 address of a link. The
Mask Length indicates the length of the IPv4 address mask.
The format of the sub-TLV for a local IPv6 address with mask length
is illustrated below.
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 (stTBD2) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Address (16 bytes) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask Length |
+-+-+-+-+-+-+-+-+
The IPv6 Address indicates the local IPv6 address of a link. The
Mask Length indicates the length of the IPv6 address mask.
4.2. Procedures
4.2.1. ISIS Router Procedure
For a broadcast inter-AS link connecting to multiple ASBRs, each of
the ASBRs as an ISIS router advertises an LSP with an inter-AS
reachability TLV, which contains sub-TLVs for the information such as
1) 10 8) about the broadcast link described in Section 3. It does
not contain any sub-TLVs indicating remote ASBR, instead, it includes
a sub-TLV for the local IP address with network mask.
When TE is enabled on an inter-AS link and the link is up, the ASBR
SHOULD advertise this link using the normal procedures for ISIS-TE.
When either the link is down or TE is disabled on the link, the ASBR
SHOULD withdraw the advertisement. When there are changes to the TE
parameters for the link (for example, when the available bandwidth
changes), the ASBR SHOULD re-advertise the link but MUST take
precautions against excessive re-advertisements.
4.2.2. Super Node Procedure
Suppose that there is a super node, which just receives LSPs from
each of ASes (or domains) through a passive ISIS adjacency between
the super node and an ASBR or a normal router in the AS or domain.
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For a new broadcast link connecting multiple routers, when the super
node receives an LSP containing the link attached to router X, it
stores the link from X into its TED. It finds the link's remote end
P using the link's local IP address with network mask. P is a Pseudo
node identified by the local IP address of the DR selected from the
routers connected to the link. After finding P, it associates the
link attached to X with P and the link connected to P with X. If P
is not found, a new Pseudo node P is created. The super node
associates the link attached to X with P and the link attached to P
with X. This creates a bidirectional connection between X and P.
The first router and second router from which the super node receives
an LSP containing the link are selected as the DR and BDR
respectively. After the DR is down, the BDR becomes the DR and the
router other than the DR with the largest (or smallest) local IP
address connecting to the link is selected as the BDR.
When the old DR is down and the BDR becomes the new DR, the super
node updates its TED through removing the link between each of
routers X and old P (the Pseudo node corresponding to the old DR) and
adding a link between each of routers X (still connecting to the
broadcast link) and new P (the Pseudo node corresponding to the new
DR).
5. Security Considerations
The mechanism described in this document does not raise any new
security issues for the ISIS protocols.
6. IANA Considerations
This section specifies requests for IANA allocation.
7. Acknowledgement
The authors would like to thank all for their valuable comments on
this draft.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
December 2008, <https://www.rfc-editor.org/info/rfc5316>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
8.2. Informative References
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
DOI 10.17487/RFC6805, November 2012,
<https://www.rfc-editor.org/info/rfc6805>.
Authors' Addresses
Huaimo Chen
Futurewei
Boston, MA,
United States of America
Email: hchen@futurewei.com
Mehmet Toy
Verizon
United States of America
Email: mehmet.toy@verizon.com
Xufeng Liu
Volta Networks
McLean, VA
United States of America
Email: xufeng.liu.ietf@gmail.com
Lei Liu
Fujitsu
United States of America
Email: liulei.kddi@gmail.com
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Zhenqiang Li
China Mobile
No.32 Xuanwumenxi Ave., Xicheng District
Beijing
100032
P.R. China
Email: li_zhenqiang@hotmail.com
Yi Yang
IBM
NC
United States of America
Email: yyang1998@gmail.com
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