Internet DRAFT - draft-chen-bier-idr-bier-te-bgp
draft-chen-bier-idr-bier-te-bgp
BIER R. Chen
Internet-Draft B. Xu
Intended status: Standards Track Z. Zhang
Expires: 21 July 2024 ZTE Corporation
18 January 2024
BGP extensions for BIER-TE
draft-chen-bier-idr-bier-te-bgp-02
Abstract
Bit Index Explicit Replication (BIER)-TE shares architecture and
packet formats with BIER as described in [RFC8279]. BIER-TE forwards
and replicates packets based on a BitString in the packet header, but
every BitPosition of the BitString of a BIER-TE packet indicates one
or more adjacencies as described in [RFC8279].
This document describes BGP extensions for advertising the BIER-TE
specific information.
Status of This Memo
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This Internet-Draft will expire on 21 July 2024.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. BIER-TE TLV . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.1. The BIER MPLS Encapsulation sub-TLV . . . . . . . . . . . 3
3.2. The BIER non-MPLS Encapsulation sub-TLV . . . . . . . . . 4
3.3. The Bitposition sub-TLV . . . . . . . . . . . . . . . . . 4
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5.1. The new BIER-TE TLVs . . . . . . . . . . . . . . . . . . 5
5.2. The new BIER-TE Encapsulation sub-TLVs . . . . . . . . . 6
5.3. The new Bitposition sub-TLV . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Bit Index Explicit Replication (BIER)-TE shares architecture and
packet formats with BIER as described in [RFC8279]. BIER-TE forwards
and replicates packets based on a BitString in the packet header, but
every BitPosition of the BitString of a BIER-TE packet indicates one
or more adjacencies as described in [RFC9262].
This document describes BGP extensions for advertising the BIER-TE
specific information. More specifically, in this document, we define
a new optional, non-transitive BGP attribute, referred to as the
BIER-TE attribute, to convey the BIER-TE specific information.
These extensions are applicable to BGP based network scenarios.
2. 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 RFC 2119 [RFC2119].
3. BIER-TE TLV
[I-D.ietf-bier-idr-extensions] defines BIER Path attribute, and this
document reuse the Bier Path attribute. The content of the BIER Path
attribute is one or more BIER-TE TLV as shown in Figure 1. This TLV
contains BIER-TE information associated with a Prefix.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type:A 2-octet field with value TBD1, see IANA Considerations
section.
Length: 2 octets.
Subdomain-id: Unique value identifying the BIER-TE sub-domain, 1
octet.
Sub-TLVs: contains one or more sub-TLV. In this document, it defines
three sub-TLV: the BIER MPLS Encapsulation sub-TLV , the BIER non-
MPLS Encapsulation sub-TLV and the Bitposition sub-TLV.
3.1. The BIER MPLS Encapsulation sub-TLV
This sub-TLV carries the information for the BIER MPLS encapsulation
including the label range for a specific BitString length for a
certain < MT,SD >. It is advertised within the BIER-TE TLV. This
sub-TLV MAY appear multiple times within a single BIER-TE sub-TLV.
If the same BitString length is repeated in multiple sub-TLVs inside
the same BIER-TE TLV, the BIER-TE TLV MUST be ignored.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI |BS Len | Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type:A 2-octet field with value TBD2.
Length:4
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Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the
encapsulation for this BIER subdomain for this BitString length, 1
octet. Each SI maps to a single label in the label range. The first
label is for SI=0, the second label is for SI=1, etc. If the label
associated with the Maximum Set Identifier exceeds the 20-bit range,
the sub-sub-TLV MUST be ignored.
Local BitString Length (BS Len): Encoded BitString length as per
[RFC8296]. 4 bits.
Label: First label of the range, 20 bits. The labels are as defined
in [RFC8296].
3.2. The BIER non-MPLS Encapsulation sub-TLV
The sub-TLV is advertised within the BIER-TE TLV.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI |BS Len | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
Type:A 2-octet field with value TBD3.
Length:4
Max SI: Maximum Set Identifier (Section 1 of [RFC8279]) used in the
encapsulation for this BIER subdomain for this BitString length, 1
octet. The first BIFT-id is for SI=0, the second BIFT-id is for
SI=1, etc. If the BIFT-id associated with the Maximum Set Identifier
exceeds the 20-bit range, the sub-TLV MUST be ignored.
Local BitString Length (BS Len): Encoded BitString length as per
[RFC8296]. 4 bits.
BIFT-id: A 20 bit field encoding the first BIFT-id of the BIFT-id
range. BIFT-id as per [I-D.ietf-bier-lsr-non-mpls-extensions].
3.3. The Bitposition sub-TLV
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjacency address-1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition-n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjacency address-n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
Type:A 2-octet field with value TBD4.
Length:4 if the Nexthop is IPv4 address and 16 if the Nexthop is IPv6
address
<BitPosition,Adjacency address>: A 2-octet field encoding the
BitPosition associated with a adjacency address. Each adjacency
address is a local or remote neighbor address.
The Bitposition sub-TLV is included in the BIER-TE TLV.
4. Acknowledgements
The authors would like to thank Zhaohui Zhang for his valuable
suggestions.
5. IANA Considerations
The document requests new allocations from the IANA registries as
follows:
5.1. The new BIER-TE TLVs
This document requests assigning code-points from the "BGP BIER Path
Attribute Types" registry for the new BIER-TE TLV.
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+-------------------+-----------------------------+-----------------+
| TLV Code Point | Description | Value defined |
+-------------------+-----------------------------+-----------------+
| TBD1 | BIER-TE | this document |
+-------------------+-----------------------------+-----------------+
Figure 5
5.2. The new BIER-TE Encapsulation sub-TLVs
This document requests assigning code-points from the "BGP BIER-TE
TLV sub-TLV Types" for the new BIER-TE Encapsulation sub-TLVs.
+----------------------+-----------------------------+-----------------+
| Sub-TLV Code Point | Description | Value defined |
+----------------------+-----------------------------+-----------------+
| TBD2 | BIER MPLS Encapsulation | this document |
+----------------------+-----------------------------+-----------------+
| TBD3 | BIER non-MPLS Encapsulation | this document |
+----------------------+-----------------------------+-----------------+
Figure 6
5.3. The new Bitposition sub-TLV
This document requests assigning code-points from the "BGP BIER-TE
TLV sub-TLV Types" for the new Bitposition sub-TLV.
+----------------------+-----------------------------+-----------------+
| Sub-TLV Code Point | Description | Value defined |
+----------------------+-----------------------------+-----------------+
| TBD4 | Bitposition sub-TLV | this document |
+----------------------+-----------------------------+-----------------+
Figure 7
6. Security Considerations
TBD.
7. Normative References
[I-D.ietf-bier-idr-extensions]
Xu, X., Chen, M., Patel, K., Wijnands, I., Przygienda, T.,
and Z. J. Zhang, "BGP Extensions for BIER", Work in
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Progress, Internet-Draft, draft-ietf-bier-idr-extensions-
10, 13 June 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-bier-idr-extensions-10>.
[I-D.ietf-bier-lsr-non-mpls-extensions]
Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, Z.
J., and J. Xie, "LSR Extensions for BIER non-MPLS
Encapsulation", Work in Progress, Internet-Draft, draft-
ietf-bier-lsr-non-mpls-extensions-01, 19 September 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-bier-
lsr-non-mpls-extensions-01>.
[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>.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<https://www.rfc-editor.org/info/rfc4915>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
[RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
for Bit Index Explicit Replication (BIER) in MPLS and Non-
MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
2018, <https://www.rfc-editor.org/info/rfc8296>.
[RFC9262] Eckert, T., Ed., Menth, M., and G. Cauchie, "Tree
Engineering for Bit Index Explicit Replication (BIER-TE)",
RFC 9262, DOI 10.17487/RFC9262, October 2022,
<https://www.rfc-editor.org/info/rfc9262>.
Authors' Addresses
Ran Chen
ZTE Corporation
Nanjing
China
Email: chen.ran@zte.com.cn
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Benchong Xu
ZTE Corporation
Nanjing
China
Email: xu.benchong@zte.com.cn
Zheng Zhang
ZTE Corporation
Nanjing
China
Email: zhang.zheng@zte.com.cn
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