Internet DRAFT - draft-chen-ospf-ias-lk
draft-chen-ospf-ias-lk
OSPF Working Group H. Chen
Internet-Draft Futurewei
Intended status: Experimental M. Toy
Expires: 13 July 2024 Verizon
X. Liu
Alef Edge
L. Liu
Fujitsu
Z. Li
China Mobile
Y. Yang
IBM
10 January 2024
OSPF Extensions for Broadcast Inter-AS TE Link
draft-chen-ospf-ias-lk-12
Abstract
This document presents extensions to the Open Shortest Path First
(OSPF) 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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 13 July 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
Chen, et al. Expires 13 July 2024 [Page 1]
Internet-Draft inter-as-te-link January 2024
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.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Information on Inter-AS TE Link . . . . . . . . . . . . . . . 3
4. Extensions to OSPF . . . . . . . . . . . . . . . . . . . . . 3
4.1. sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 3
4.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 4
4.2.1. OSPF Router Procedure . . . . . . . . . . . . . . . . 4
4.2.2. Super Node Procedure . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
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 5392 defines a new Opaque LSA, the Inter-AS-TE-v2 LSA, for
advertising the OSPFv2 link; and a new OSPFv3 LS type, Inter-AS-TE-v3
LSA, for advertising the OSPFv3 link.
Both the Inter-AS-TE-v2 LSA and Inter-AS-TE-v3 LSA contain one top
level TLV:
2 - Link TLV
The Link TLV describes a single link and includes a set of sub-TLVs.
The Link ID sub-TLV defined in RFC 3630 MUST NOT be used in the Link
TLV of an Inter-AS-TE-v2 LSA, and the Neighbor ID sub-TLV defined in
RFC 5329 MUST NOT be used in the Link TLV of an Inter-AS-TE-v3 LSA.
Chen, et al. Expires 13 July 2024 [Page 2]
Internet-Draft inter-as-te-link January 2024
Instead, the remote ASBR is identified by the inclusion of Remote AS
Number sub-TLV and IPv4/IPv6 Remote ASBR ID sub-TLV, which is defined
in RFC 5392.
For a P2P inter-AS link, the information about its remote ASBR for
replacing its link ID may be configured. For a broadcast inter-AS
link, its link ID is the interface IP address of the designated
router (DR) of the link in OSPF. Since no OSPF runs over any
broadcast inter-AS link, no DR or backup DR (BDR) is selected. It is
hard to configure a replacement for DR and BDR.
This document presents extensions to OSPF for advertising broadcast
inter-AS TE links through defining a new sub-TLV for a broadcast link
without configuring any replacement for DR and BDR on the link.
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 link ID (i.e., DR's interface address) may be
obtained.
4. Extensions to OSPF
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.
Chen, et al. Expires 13 July 2024 [Page 3]
Internet-Draft inter-as-te-link January 2024
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 |
+-+-+-+-+-+-+-+-+
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. OSPF Router Procedure
For a broadcast inter-AS link connecting to multiple ASBRs, each of
the ASBRs as an OSPF router advertises an LSA (Inter-AS-TE-v2 LSA for
OSPFv2 or Inter-AS-TE-v3 LSA for OSPFv3) with a link TLV containing
sub-TLVs for the information such as 1) 10 8) on the broadcast link
described in Section 3.
Chen, et al. Expires 13 July 2024 [Page 4]
Internet-Draft inter-as-te-link January 2024
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 OSPF-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 LSAs from
each of ASes (or domains) through a passive OSPF adjacency between
the super node and an ASBR or ABR in the AS or domain.
For a new broadcast link connecting multiple routers with no link ID
configured, when the super node receives an LSA 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 LSA containing the link are selected as the DR and BDR
respectively. After the DR is down, the BDR node 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 OSPF protocols.
6. IANA Considerations
This section specifies requests for IANA allocation.
Chen, et al. Expires 13 July 2024 [Page 5]
Internet-Draft inter-as-te-link January 2024
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>.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392,
January 2009, <https://www.rfc-editor.org/info/rfc5392>.
[RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, DOI 10.17487/RFC5329, September 2008,
<https://www.rfc-editor.org/info/rfc5329>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
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: Huaimo.chen@futurewei.com
Chen, et al. Expires 13 July 2024 [Page 6]
Internet-Draft inter-as-te-link January 2024
Mehmet Toy
Verizon
United States of America
Email: mehmet.toy@verizon.com
Xufeng Liu
Alef Edge
United States of America
Email: xufeng.liu.ietf@gmail.com
Lei Liu
Fujitsu
United States of America
Email: liulei.kddi@gmail.com
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
Chen, et al. Expires 13 July 2024 [Page 7]
