BIER WG Z. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track A. Przygienda
Expires: May 3, 2017 Juniper Networks
October 30, 2016
BIER in BABEL
draft-zhang-bier-babel-extensions-00
Abstract
BIER introduces a novel architecture for multicast packet forwarding.
It does not require a signalling 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 ordinary wired as well as in
wireless mesh networks. This document defines a way to carry BIER
information in Babel.
Status of This Memo
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This Internet-Draft will expire on May 3, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
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 . . . . . . . . . . . . . . 3
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. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
[I-D.ietf-bier-architecture] introduces a novel architecture for
multicast data packets forwarding. It does not require a signalling
protocol to explicitly build multicast distribution trees, nor does
it require intermediate nodes to maintain any per-flow state. All
the necessary extensions to perform this functionality are
abbreviated by the "BIER architecture" moniker.
BIER information can be carried in OSPF and ISIS routing protocol as
defined in [I-D.ietf-bier-isis-extensions] and
[I-D.ietf-bier-ospf-bier-extensions] respectively. The according
tables for BIER forwarding purposes are built when OSPF/ISIS performs
according calculations on the advertised information.
[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].
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3. Advertisement of BIER information
3.1. BIER BFR-prefix and BIER sub-TLV
BFR-prefix and according information is carried in a Babel Update TLV
per [RFC6126]. Several new sub-TLVs and sub-sub-TLVs are defined to
convey further BIER information such as BFR-id, sub-domain-id and
BSL.
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
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
[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.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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.draft-ietf-bier-mpls-encapsulation-05]. 4 bits.
o Label Range Size: Number of labels in the range used on
encapsulation for this BIER sub-domain for this bitstring length,
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. Security Considerations
TBD
5. 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.
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6. Normative References
[I-D.ietf-babel-rfc6126bis]
Chroboczek, J., "The Babel Routing Protocol", draft-ietf-
babel-rfc6126bis-00 (work in progress), August 2016.
[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-05 (work in
progress), October 2016.
[I-D.ietf-bier-isis-extensions]
Ginsberg, L., Przygienda, T., Aldrin, S., and Z. Zhang,
"BIER support via ISIS", draft-ietf-bier-isis-
extensions-03 (work in progress), September 2016.
[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 Networks", draft-ietf-bier-
mpls-encapsulation-05 (work in progress), July 2016.
[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-04 (work
in progress), September 2016.
[I-D.pfister-bier-over-ipv6]
Pfister, P. and I. Wijnands, "An IPv6 based BIER Routing
Underlay", draft-pfister-bier-over-ipv6-00 (work in
progress), September 2016.
[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
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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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