| Internet-Draft | OSPFv2 for BIER-TE | April 2023 |
| Chen, et al. | Expires 29 October 2023 | [Page] |
- Workgroup:
- Network Working Group
- Internet-Draft:
- draft-ietf-bier-te-ospf-05
- Published:
- Intended Status:
- Standards Track
- Expires:
OSPFv2 Extensions for BIER-TE
Abstract
This document describes OSPFv2 extensions for distributing the BitPositions configured on a Bit-Forwarding Router (BFR) in a "Bit Index Explicit Replication Traffic Engineering" (BIER-TE) domain.¶
Requirements Language
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] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
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 29 October 2023.¶
Copyright Notice
Copyright (c) 2023 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. 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.¶
1. Introduction
[RFC9262] introduces Bit Index Explicit Replication (BIER) Traffic/Tree Engineering (BIER-TE). It is an architecture for per-packet stateless explicit point to multipoint (P2MP) multicast path/tree. There are three types of BitPositions (BPs) in a BIER-TE domain: link BitPosition (BP), routed BP and localdecap BP. A link BP is a BP configured on a link from Bit-Forwarding Router (BFR) X to BFR Y for a forward connected adjacency from X to Y. A routed BP is a BP configured on BFR X for a forward routed adjacency from X to a remote BFR Z not directly connected to X. A localdecap BP is a BP configured on a BFR.¶
[RFC8444] describes OSPFv2 Extensions for distributing the BFR identifier (BFR-id) configured on a BFR. This document specifies OSPFv2 extensions for distributing the BitPositions configured a BFR in a BIER-TE domain. The BitPositions distributed may be used by a BFR as a Point of Local Repair (PLR) for Fast-ReRoute (FRR).¶
2. Extensions to OSPFv2
This section describes protocol extensions to OSPFv2 for distributing the BitPositions configured on a BFR in a BIER-TE domain.¶
2.1. Link BitPosition
This section defines a Sub-TLV for distributing a link BitPosition (BP).¶
[RFC7684] defines the OSPFv2 Extended Link TLV to advertise the information about a link. Multiple Link TLVs for the links of a router are included in the OSPFv2 Extended Link Opaque LSA of the router. The OSPFv2 Extended Link TLV has the following format:¶
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 (1) | Length (Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type:
- 1.¶
- Length:
- Variable, dependent on Sub-TLVs.¶
- Link Type, Link ID and Link Data:
- They are defined in Section A.4.2 of [RFC2328].¶
- Reserved:
- MUST be set to 0 on transmission and MUST be ignored on reception.¶
Under the OSPFv2 Extended Link TLV for a link, a Sub-TLV, called Link-BP Sub-TLV, is defined for distributing a link BitPosition. A Link-BP Sub-TLV is included in the Link TLV for a link of Link Type P2P (Point-to-Point) or Broadcast (or say LAN or Transit Network). The Link-BP Sub-TLV has the following format:¶
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 (TBD1) | Length(6/8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id | MT-ID | BAR | IPA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition | DrEndBitPosition |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type:
- TBD1 is to be assigned by IANA.¶
- Length:
- Variable. For a P2P link, it is 6 since there is no DrEndBitPosition. For a broadcast link, it is 8 since there is a DrEndBitPosition.¶
- sub-domain-id:
- Unique value identifying a BIER-TE sub-domain.¶
- MT-ID:
- Multi-Topology ID identifying the topology that is associated with the BIER-TE sub-domain.¶
- BAR:
- Single-octet BIER Algorithm used to calculate underlay paths to reach other BFRs. Values are allocated from the "BIER Algorithm" registry defined in [RFC8401].¶
- IPA:
- Single-octet IGP Algorithm used to either modify, enhance, or replace the calculation of underlay paths to reach other BFRs as defined by the BAR value. Values are defined in the "IGP Algorithm Types" registry.¶
- BitPosition:
- A 2-octet field encoding the BitPosition locally configured on the link/interface when the Link Type of the link in the OSPFv2 Extended Link TLV containing this Sub-TLV is 1 (i.e., Point-to-Point connection to another router) or 2 (i.e., connection to Transit Network or say LAN).¶
- DrEndBitPosition:
- A 2-octet field encoding the BitPosition of the connection on the designated router (DR) end. This field exists when the Link Type in the OSPFv2 Extended Link TLV containing this Sub-TLV is 2 (i.e., Transit Network or LAN). For the other value of the Link Type, this field MUST NOT exist. The DrEndBitPosition may be configured on the link/interface to a transit network (i.e., broadcast link or say LAN) as described in [I-D.chen-bier-te-lan].¶
2.2. Routed and Localdecap BitPositions
A TLV, called Node BPs TLV, is defined within the body of the OSPF Router Information (RI) Opaque Link State Advertisement (LSA) [RFC7770]. The TLV contains Sub-TLVs. Two types of Sub-TLVs are defined. One is for a Routed BitPosition and the other for a Localdecap BitPosition.¶
The Node BPs TLV has the following format:¶
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 (TBD2) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type:
- TBD2 is to be assigned by IANA.¶
- Length:
- Variable.¶
- Sub-TLVs:
- Sub-TLVs containing the Routed BitPositions and Localdecap BitPosition configured on a BFR.¶
The Routed-BP Sub-TLV has the following format:¶
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 (1) | Length(8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id | MT-ID | BAR | IPA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition | BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type:
- 1 is the type for routed BP.¶
- Length:
- It is 8.¶
- BitPosition:
- A 2-octet field encoding the BitPosition configured on a BFR for a forward routed adjacency to a remote BFR.¶
- BFR-id:
- A 2-octet field encoding the BFR-id of the remote BFR.¶
- sub-domain-id, MT-ID, BAR and IPA:
- They are the same as those described in Section 2.1.¶
The Localdecap-BP Sub-TLV has the following format:¶
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 (T2) | Length(6) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id | MT-ID | BAR | IPA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Type:
- 2 is the type for localdecap BP.¶
- Length:
- It is 6.¶
- BitPosition:
- A 2-octet field encoding the localdecap BitPosition configured on a BFR.¶
- sub-domain-id, MT-ID, BAR and IPA:
- They are the same as those described Section 2.1.¶
3. Security Considerations
Protocol extensions defined in this document do not affect the OSPF security other than those as discussed in the Security Considerations section of [RFC7684].¶
4. IANA Considerations
Under "OSPFv2 Extended Link TLV Sub-TLVs" registry as defined in [RFC7684], IANA is requested to assign a new registry value for Link-BP Sub-TLV as follows:¶
+==============+===================+=====================+ | Value | Description | reference | +==============+===================+=====================+ | TBD1 (25) | Link-BP | This document | +--------------+-------------------+---------------------+¶
Under "OSPF Router Information (RI) TLVs" registry as defined in [RFC7770], IANA is requested to assign a new registry value for Node BPs TLV as follows:¶
+==============+===================+=====================+ | Value | Description | reference | +==============+===================+=====================+ | TBD2 (21) | Node BPs | This document | +--------------+-------------------+---------------------+¶
IANA is requested to create a new subregistry called the "OSPF Node BPs Sub-TLVs" under the "Open Shortest Path First (OSPF) Parameters" registry. The initial values are as follows:¶
+===========+===================+========================+ | Value | Description | reference | +===========+===================+========================+ | 0 | Reserved | This document | +-----------+-------------------+------------------------+ | 1 | Routed BP | This document | +-----------+-------------------+------------------------+ | 2 | Localdecap BP | This document | +-----------+-------------------+------------------------+ | 3 - 65535 | To be allocated in First Come First Served| +-----------+-------------------+------------------------+¶
5. References
5.1. Normative References
- [RFC2119]
- Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
- [RFC2328]
- Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, , <https://www.rfc-editor.org/info/rfc2328>.
- [RFC7684]
- Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, , <https://www.rfc-editor.org/info/rfc7684>.
- [RFC7770]
- Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, , <https://www.rfc-editor.org/info/rfc7770>.
- [RFC8174]
- Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
- [RFC9262]
- Eckert, T., Ed., Menth, M., and G. Cauchie, "Tree Engineering for Bit Index Explicit Replication (BIER-TE)", RFC 9262, DOI 10.17487/RFC9262, , <https://www.rfc-editor.org/info/rfc9262>.
5.2. Informative References
- [I-D.chen-bier-te-lan]
- Chen, H., McBride, M., Wang, A., Mishra, G. S., Liu, L., and X. Liu, "BIER-TE for Broadcast Link", Work in Progress, Internet-Draft, draft-chen-bier-te-lan-06, , <https://datatracker.ietf.org/doc/html/draft-chen-bier-te-lan-06>.
- [RFC8401]
- Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. Zhang, "Bit Index Explicit Replication (BIER) Support via IS-IS", RFC 8401, DOI 10.17487/RFC8401, , <https://www.rfc-editor.org/info/rfc8401>.
- [RFC8444]
- Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 Extensions for Bit Index Explicit Replication (BIER)", RFC 8444, DOI 10.17487/RFC8444, , <https://www.rfc-editor.org/info/rfc8444>.
Acknowledgments
The authors would like to thank Acee Lindem, Les Ginsberg, Tony Przygienda, Jeffrey Zhang and Toerless Eckert for their comments on this work.¶
