Internet DRAFT - draft-cz-bier-bgp-ls-bier-te-ext
draft-cz-bier-bgp-ls-bier-te-ext
BIER R. Chen
Internet-Draft Z. Zhang
Intended status: Standards Track ZTE Corporation
Expires: 24 April 2023 Y. Liu
China Mobile
21 October 2022
BGP-LS extensions for BIER-TE
draft-cz-bier-bgp-ls-bier-te-ext-01
Abstract
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].
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
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
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Internet-Drafts are draft documents valid for a maximum of six months
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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 24 April 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for BIER-TE . . . . . . . . . . . . . . . . 3
3.1. The BIER-TE information TLV . . . . . . . . . . . . . . . 3
3.2. The MPLS Encapsulation TLV . . . . . . . . . . . . . . . 5
3.3. The non-MPLS Encapsulation TLV . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. Normative References . . . . . . . . . . . . . . . . . . . . 7
8. Informative references . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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].
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.
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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
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. 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. 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 TLVs defined
in this section and associated with the BGP-LS Link NLRI.
Given that the BIER-TE informations are associated with the link or
adjacency , the link Attribute TLV [RFC7752] can be used to carry the
BIER-TE informations. The new Prefix Attribute TLVs are defined for
the encoding of BIER-TE informations.
3.1. The BIER-TE information 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.ietf-bier-te-isis]) BIER-TE sub-TLV of
OSPFv2 (section 2 of [I-D.ietf-bier-te-ospf]) and OSPFv3 (section 2
of [I-D.ietf-bier-te-ospfv3]). According to different subdomain, the
BIER-TE information TLV may appear multiple times.
The following BIER-TE information TLV is defined:
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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 (TBD ) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id | BAR | IPA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitPosition | EndBitPosition |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type: TBD, see IANA Considerations section.
Length: 2 octets.
Subdomain-id: Unique value identifying 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), as defined in section
2 of [I-D.ietf-bier-te-isis] , section 2 of [I-D.ietf-bier-te-ospf]
and [I-D.ietf-bier-te-ospfv3].
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3.2. The MPLS Encapsulation TLV
The MPLS Encapsulation TLV is used in order to advertise MPLS
specific informations used for BIER-TE. It MAY appear multiple
times. The informations are derived from MPLS Encapsulation Sub-sub-
TLV of IS-IS(section 3.1 of [I-D.zwx-bier-te-isis-extensions]), MPLS
Encapsulation Sub-sub-TLV of OSPFv2 (section 3.1 of
[I-D.zwx-bier-te-ospf-extensions]) and OSPFv3 (section 3.1 of
[I-D.zwx-bier-te-ospfv3-extensions]).
In some environment, each router allocates its labels, and advertises
it to the controller.That solution is simpler as the controller does
not need to deal with label allocation. If the controller has to
deal with Label allocation , there needs to be a (global) range
carved out such there are no conflicts. We can avoid all that by
having the router allocate the BIER Label range and advertise it to
the controller.
The following the MPLS Encapsulation TLV is defined:
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: TBD, see IANA Considerations section.
Length: 4.
Max SI: A 1-octet field encoding the maximum Set Identifier(as
defined in [RFC8279]), used in the encapsulation for this BIER
subdomain for this BitString length.
BS Len: A 4-bit field field encoding the Bitstring length as per
[RFC8296].
Label: First label of the range, 20 bits. The labels are as defined
[RFC8296]. The 4 leftmost bits MUST be ignored.
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BS length in multiple MPLS Encapsulation TLV associated with the same
BIER-TE information TLV MUST NOT repeat, otherwise only the first
MPLS Encapsulation TLV with such BS length MUST be used and any
subsequent MPLS Encapsulation TLVs with the same BS length MUST be
ignored.
3.3. The non-MPLS Encapsulation TLV
The non-MPLS Encapsulation TLV is used in order to advertise non-MPLS
encapsulation(e.g. ethernet encapsulation ) capability and other
associated parameters of the encapsulation. It MAY appear multiple
times. The informations are derived from non-MPLS Encapsulation Sub-
sub-TLV of IS-IS(section 3.2 of [[I-D.zwx-bier-te-isis-extensions]]),
non-MPLS Encapsulation Sub-sub-TLV of OSPFv2 (section 3.2 of
[[I-D.zwx-bier-te-ospf-extensions]]) and OSPFv3 (section 3.2 of
[[I-D.zwx-bier-te-ospfv3-extensions]]).
The following the non-MPLS Encapsulation TLV is defined:
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: TBD, see IANA Considerations section.
Length: 4.
Max SI:A 1-octet field encoding the maximum Set Identifier(as defined
in [RFC8279]), used in the encapsulation for this BIER subdomain for
this BitString length.
The "BIFT-id range" is the set of 20-bit values beginning with the
BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range
is allocated for each BitString length and sub-domain-id. These
BIFT-id's are used for BIER forwarding as described in [RFC8279])and
[RFC8296].
Local BitString Length (BS Len): A 4-bit field encoding the Bitstring
length as per [RFC8296].
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BIFT-id:A 20bit field encoding the first BIFT-id of the BIFT-id
range. The BIER-id are as defined in
[I-D.ietf-bier-lsr-non-mpls-extensions].
4. IANA Considerations
This document requests assigning code-points from the registry for
the new link Attribute TLVs.
+================+========================+===============+
| TLV Code Point | Description | Value defined |
+================+========================+===============+
| TBD1 | BIER-TE information | this document |
+----------------+------------------------+---------------+
| TBD2 | MPLS Encapsulation | this document |
+----------------+------------------------+---------------+
| TBD3 | non-MPLS Encapsulation | this document |
+----------------+------------------------+---------------+
Table 1: The new link Attribute TLVs
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. Normative References
[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://www.ietf.org/archive/id/draft-ietf-bier-lsr-non-
mpls-extensions-01.txt>.
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[I-D.ietf-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", Work
in Progress, Internet-Draft, draft-ietf-bier-te-isis-02, 2
August 2022, <https://www.ietf.org/archive/id/draft-ietf-
bier-te-isis-02.txt>.
[I-D.ietf-bier-te-ospf]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "OSPF Extensions for BIER-TE", Work
in Progress, Internet-Draft, draft-ietf-bier-te-ospf-01,
29 July 2022, <https://www.ietf.org/archive/id/draft-ietf-
bier-te-ospf-01.txt>.
[I-D.ietf-bier-te-ospfv3]
Chen, H., McBride, M., Wang, A., Mishra, G. S., Fan, Y.,
Liu, L., and X. Liu, "OSPFv3 Extensions for BIER-TE", Work
in Progress, Internet-Draft, draft-ietf-bier-te-ospfv3-01,
5 July 2022, <https://www.ietf.org/archive/id/draft-ietf-
bier-te-ospfv3-01.txt>.
[I-D.zwx-bier-te-isis-extensions]
Zhang, Z., Wei, Y., and B. Xu, "IS-IS extensions for BIER-
TE (Tree Engineering for Bit Index Explicit Replication)
with MPLS and non-MPLS Encapsulation", Work in Progress,
Internet-Draft, draft-zwx-bier-te-isis-extensions-01, 24
July 2022, <https://www.ietf.org/archive/id/draft-zwx-
bier-te-isis-extensions-01.txt>.
[I-D.zwx-bier-te-ospf-extensions]
Zhang, Z., Wei, Y., and B. Xu, "OSPFv2 extensions for
BIER-TE (Tree Engineering for Bit Index Explicit
Replication) with MPLS and non-MPLS Encapsulation", Work
in Progress, Internet-Draft, draft-zwx-bier-te-ospf-
extensions-00, 5 July 2022,
<https://www.ietf.org/archive/id/draft-zwx-bier-te-ospf-
extensions-00.txt>.
[I-D.zwx-bier-te-ospfv3-extensions]
Zhang, Z., Wei, Y., and B. Xu, "OSPFv3 extensions for
BIER-TE (Tree Engineering for Bit Index Explicit
Replication) with MPLS and non-MPLS Encapsulation", Work
in Progress, Internet-Draft, draft-zwx-bier-te-ospfv3-
extensions-01, 24 July 2022,
<https://www.ietf.org/archive/id/draft-zwx-bier-te-ospfv3-
extensions-01.txt>.
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[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>.
[RFC4655] Farrel, A., Vasseur, J.-P., 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>.
[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>.
[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>.
[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>.
[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>.
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8. 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
Ran Chen
ZTE Corporation
Nanjing
China
Email: chen.ran@zte.com.cn
Zheng Zhang
ZTE Corporation
Nanjing
China
Email: zhang.zheng@zte.com.cn
Yisong Liu
China Mobile
Beijing
China
Email: liuyisong@chinamobile.com
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