Networking Working Group R. Chen
Internet-Draft Zh. Zhang
Intended status: Standards Track ZTE Corporation
Expires: February 5, 2022 August 4, 2021
BGP Link-State extensions for BIER-TE
draft-cz-bier-bgp-ls-bier-te-ext-00
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 [I-D.ietf-bier-te-arch].
BGP Link-State (BGP-LS) enables the collection of various topology
informations from the network, and the topology informations are used
by the PCE to calculate the path and then propagate them onto the
BFRs(instead of having each node to calculate on its own) and that
can be for both inter-as and intra-as situations.
This document specifies extensions to the BGP Link-state address-
family in order to advertise BIER-TE informations.
Status of This Memo
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This Internet-Draft will expire on February 5, 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . . 3
3.1. The new Link Attribute TLV . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative references . . . . . . . . . . . . . . . . . . 5
7.2. Informative references . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
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 [[I-D.ietf-bier-te-arch]].
When BIER-TE is enabled in an IGP domain, BIER-TE-related
informations will be advertised via IGP link-state routing protocols.
The flooding scope for the IGP extensions for BIER-TE is IGP area-
wide. by using the IGP alone it is not enough to construct across
multiple IGP Area.
The BGP-LS address-family/sub-address-family have been defined to
allow BGP to carry Link-State informations. This document specifies
extensions to the BGP Link-state address-family in order to advertise
BIER-TE-specific informations, Similar to BGP-LS Advertisement of IGP
Traffic Engineering Performance Metric Extensions([RFC8571]). An
external component (e.g., a controller/a PCE(see [RFC4655] for PCE-
Based Architecture , [RFC5440] for PCEP and [RFC5376] for Inter-AS
Requirements for the PCEP.))then can learn the BIER-TE informations
in the "northbound" direction and calculate BIER-TE Path and then
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propagate them onto BFRs (instead of having each BFR to calculate on
its own), and that can be for both inter-as and intra-as situations.
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. BGP-LS Extensions for BIER-TE
BIER-TE attributes and BitPositions associated with a link or
adjacency are advertised using the BGP-LS link Attribute TLV defined
in this section and associated with the BGP-LS Link NLRI.
3.1. The new Link Attribute TLV
The BIER-TE information TLV is defined to advertise the BIER-TE
informations. The informations are derived from BIER-TE Info Sub-TLV
of IS-IS(section 2 of [[I-D.chen-bier-te-isis]]) BIER-TE sub-TLV of
OSPFv2 (section 2 of [[I-D.chen-bier-te-ospf]]) and OSPFv3 (section 2
of [[I-D.chen-bier-te-ospfv3]]). According to different subdomain,
the BIER-TE information TLV may appear multiple times.
The BIER-TE information 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id | MT-ID | BAR | IPA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition | EndBitPosition |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The BIER-TE information TLV
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.
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MT-ID: Multi-Topology ID that identifies the topology that is
associated with the BIER-TE sub-domain. 1 octet.
BAR: A 1-octet field encoding the BIER Algorithm, used to calculate
underlay paths to reach BFERs. Values are allocated from the "BIER
Algorithms" registry which is defined in [RFC8401].
IPA: A 1-octet field encoding the IGP Algorithm, used to either
modify,enhance, or replace the calculation of underlay paths to reach
BFERs as defined by the BAR value. Values are from the IGP Algorithm
registry.
BitPosition: A 2-octet field encoding the BitPosition locally
configured on the link/interface when the Link Type of the link in
the Router-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).
EndBitPosition: A 2-octet field encoding the BitPosition of the
connection on the designated Intermediate Systems (Dis) end (ISIS) /
designated router (DR) end( OSPFv2 and OSPFv3). For ISIS, this field
is valid when the neighbor is a pseudonode. If the neighbor is not a
pseudonode, this field MUST be ignored. For OSPFv2 and OSPFv3, this
field is valid when the Link Type in the Router-Link TLV containing
this Sub-TLV is 2 (i.e., Transit Network or LAN) and for the other
value of the Link Type, this field MUST be ignored. The
EndBitPosition may be configured on the link/interface to a transit
network (i.e., broadcast link or say LAN).
If the MT-ID value is outside of the values specified in [RFC4915],
the BIER-TE information Sub-TLV MUST be ignored.
4. IANA Considerations
This document requests assigning code-points from the registry for
the new Link Attribute TLV.
+-------------------+-----------------------------+-----------------+
| TLV Code Point | Description | Value defined |
+-------------------+-----------------------------+-----------------+
| TBD1 | BIER-TE information | this document |
+-------------------+-----------------------------+-----------------+
Table 1: The new Link Attribute TLV
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5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the "Security
Considerations"section of [RFC4271] for a discussion of BGP security.
Security considerations for acquiring and distributing BGP-LS
information are discussed in [RFC7752].
6. Acknowledgements
TBD.
7. References
7.1. Normative references
[I-D.chen-bier-te-isis]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "IS-IS Extensions for BIER-TE",
draft-chen-bier-te-isis-01 (work in progress), July 2021.
[I-D.chen-bier-te-ospf]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "OSPF Extensions for BIER-TE", draft-
chen-bier-te-ospf-02 (work in progress), July 2021.
[I-D.chen-bier-te-ospfv3]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "OSPFv3 Extensions for BIER-TE",
draft-chen-bier-te-ospfv3-02 (work in progress), July
2021.
[I-D.ietf-bier-te-arch]
Eckert, T., Cauchie, G., and M. Menth, "Tree Engineering
for Bit Index Explicit Replication (BIER-TE)", draft-ietf-
bier-te-arch-10 (work in progress), July 2021.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[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>.
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[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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>.
[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, June 2018,
<https://www.rfc-editor.org/info/rfc8401>.
[RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions",
RFC 8571, DOI 10.17487/RFC8571, March 2019,
<https://www.rfc-editor.org/info/rfc8571>.
7.2. Informative references
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS
Requirements for the Path Computation Element
Communication Protocol (PCECP)", RFC 5376,
DOI 10.17487/RFC5376, November 2008,
<https://www.rfc-editor.org/info/rfc5376>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
Authors' Addresses
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Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
Zheng Zhang
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Email: zhang.zheng@zte.com.cn
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