BIER WG Z. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track A. Przygienda
Expires: December 29, 2017 Juniper Networks
June 27, 2017
BIER in BABEL
draft-zhang-bier-babel-extensions-01
Abstract
BIER introduces a novel multicast architecture. It does not require
a signaling protocol to explicitly build multicast distribution
trees, nor does it require intermediate nodes to maintain any per-
flow state.
Babel defines a distance-vector routing protocol that operates in a
robust and efficient fashion both in wired as well as in wireless
mesh networks. This document defines a way to carry necessary BIER
signaling information in Babel.
Status of This Memo
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This Internet-Draft will expire on December 29, 2017.
Copyright Notice
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document authors. All rights reserved.
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publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Advertisement of BIER information . . . . . . . . . . . . . . 2
3.1. BIER BFR-prefix and BIER sub-TLV . . . . . . . . . . . . 3
3.1.1. BIER sub-TLV . . . . . . . . . . . . . . . . . . . . 3
3.2. BIER MPLS Encapsulation sub-sub-TLV . . . . . . . . . . . 3
3.3. Optional BIER sub-domain BSL conversion sub-sub-TLV . . . 4
4. Tree types and tunneling . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[I-D.ietf-bier-architecture] introduces a novel multicast
architecture. It does not require a signaling protocol to explicitly
build multicast distribution trees, nor does it require intermediate
nodes to maintain any per-flow state. All procedures necessary to
support BIER are abbreviated by the "BIER architecture" moniker in
this document.
[RFC6126] and [I-D.ietf-babel-rfc6126bis] define a distance-vector
routing protocol under the name of "Babel". Babel operates in a
robust and efficient fashion both in ordinary wired as well as in
wireless mesh networks.
2. Terminology
The terminology of this documents follows
[I-D.ietf-bier-architecture], [RFC6126], [RFC7557] and
[I-D.ietf-babel-rfc6126bis].
3. Advertisement of BIER information
In case a router is configured with BIER information, and Babel is
the routing protocol used, such a router MAY use Babel protocol to
announce the BIER information using the BIER sub-TLV specified below.
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3.1. BIER BFR-prefix and BIER sub-TLV
BFR-prefix and according information is carried in a Babel Update TLV
per [I-D.ietf-babel-rfc6126bis]. A new sub-TLV is defined to convey
further BIER information such as BFR-id, sub-domain-id and BSL. Two
sub-sub-TLVs are carried as payload of BIER sub-TLV.
The mandatory bit of BIER sub-TLV should be set to 0. If a router
cannot recognize a sub-TLV, the router MUST ignore this unknown sub-
TLV.
3.1.1. BIER sub-TLV
The BIER sub-TLV format aligns exactly with the definition and
restrictions in [I-D.ietf-bier-isis-extensions] and
[I-D.ietf-bier-ospf-bier-extensions]. It is a sub-TLV of Babel
update TLV. The prefix MUST NOT be summarized and the according sub-
TLV MUST be treated as optional and transitive.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | subdomain-id | BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BIER sub-TLV
o Type: as indicated in IANA section.
o Length: 1 octet. Include the length of BIER sub-TLV and potential
length of the two sub-sub-TLVs.
o Reserved: MUST be 0 on transmission, ignored on reception. May be
used in future versions. 8 bits.
o subdomain-id: Unique value identifying the BIER sub-domain. 1
octet.
o BFR-id: A 2 octet field encoding the BFR-id, as documented in
[I-D.ietf-bier-architecture]. If no BFR-id has been assigned this
field is set to the invalid BFR-id.
3.2. BIER MPLS Encapsulation sub-sub-TLV
The BIER MPLS Encapsulation sub-sub-TLV can be carried by BIER sub-
TLV. The format and restrictions are aligned with
[I-D.ietf-bier-isis-extensions] and
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[I-D.ietf-bier-ospf-bier-extensions]. This sub-sub-TLV carries the
information for the BIER MPLS encapsulation including the label range
for a specific BSL for a certain <MT,SD> pair.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-sub-Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lbl Range Size|BS Len | Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MPLS Encapsulation sub-sub-TLV
o Type: value of 1 indicating MPLS encapsulation.
o Length: 1 octet
o Local BitString Length (BS Len): Encoded bitstring length as per
[I-D.ietf-bier-mpls-encapsulation]. 4 bits.
o Label Range Size: Number of labels in the range for this BIER sub-
domain and bitstring length combination, 1 octet.
o Label: First label of the range, 20 bits. The labels are as
defined in [I-D.ietf-bier-mpls-encapsulation].
3.3. Optional BIER sub-domain BSL conversion sub-sub-TLV
This sub-sub-TLV is used to carry the BSL information. Its
definition and restrictions are aligned with
[I-D.ietf-bier-isis-extensions].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-sub-Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: BSL conversion sub-sub-TLV
4. Tree types and tunneling
Since Babel is performing a diffusion computation, support for
different tree types is not as natural as with link-state protocols.
Hence this specification is assuming that normal Babel reachability
computation is performed without further modifications.
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BIER architecture does not rely on all routers in a domain performing
BFR procedures. How to support tunnels that will allow to tunnel
BIER across such routers in Babel is for further study.
5. Security Considerations
TBD
6. IANA Considerations
A new type of Babel update sub-TLV needs to be defined for BIER
information advertisement.
7. Acknowledgements
The draft is aligned with the [I-D.ietf-bier-isis-extensions] and
[I-D.ietf-bier-ospf-bier-extensions] as far as feasible.
8. Normative References
[I-D.ietf-babel-rfc6126bis]
Chroboczek, J., "The Babel Routing Protocol", draft-ietf-
babel-rfc6126bis-02 (work in progress), May 2017.
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-07 (work in
progress), June 2017.
[I-D.ietf-bier-isis-extensions]
Ginsberg, L., Przygienda, T., Aldrin, S., and Z. Zhang,
"BIER support via ISIS", draft-ietf-bier-isis-
extensions-04 (work in progress), March 2017.
[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J.,
Aldrin, S., and I. Meilik, "Encapsulation for Bit Index
Explicit Replication in MPLS and non-MPLS Networks",
draft-ietf-bier-mpls-encapsulation-07 (work in progress),
June 2017.
[I-D.ietf-bier-ospf-bier-extensions]
Psenak, P., Kumar, N., Wijnands, I., Dolganow, A.,
Przygienda, T., Zhang, Z., and S. Aldrin, "OSPF Extensions
for BIER", draft-ietf-bier-ospf-bier-extensions-06 (work
in progress), June 2017.
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[RFC6126] Chroboczek, J., "The Babel Routing Protocol", RFC 6126,
DOI 10.17487/RFC6126, April 2011,
<http://www.rfc-editor.org/info/rfc6126>.
[RFC7557] Chroboczek, J., "Extension Mechanism for the Babel Routing
Protocol", RFC 7557, DOI 10.17487/RFC7557, May 2015,
<http://www.rfc-editor.org/info/rfc7557>.
Authors' Addresses
Zheng(Sandy) Zhang
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing
China
Email: zhang.zheng@zte.com.cn
Tony Przygienda
Juniper Networks
Email: prz@juniper.net
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