Networking Working Group Ran. Chen
Internet-Draft Zheng. Zhang
Intended status: Standards Track ZTE Corporation
Expires: September 7, 2016 Vengada. Govindan
IJsbrand. Wijnands
Cisco
March 12, 2016
BGP Link-State extensions for BIER
draft-chenvgovindan-bier-bgp-ls-bier-ext-00
Abstract
Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per-
flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header
contains a bitstring in which each bit represents exactly one BFER to
forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header.
This document specifies extensions to the BGP Link-state address-
family in order to advertising BIER information.
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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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 September 7, 2016.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for BIER . . . . . . . . . . . . . . . . . 3
3.1. The BIER TLV . . . . . . . . . . . . . . . . . . . . . . 3
3.1.1. The BIER MPLS Encapsulation Sub-TLV . . . . . . . . . 4
3.2. The BIER-TE TLV . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative references . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per-
flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header
contains a bitstring in which each bit represents exactly one BFER to
forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header.
This document specifies extensions to the BGP Link-state address-
family in order to advertising BIER-specific. An external component
(e.g., a controller) then can collect BIER information in the
"northbound" direction within the BIER domain.
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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
Each BFR MUST be assigned a "BFR-Prefix". A BFR's BFR-Prefix MUST be
an IP address (either IPv4 or IPv6) of the BFR, and MUST be unique
and routable within the BIER domain as described in section 2 of
[I-D.ietf-bier-architecture], and then external component (e.g., a
controller) need to collect BIER information of BIER routers are
associated with the BFR-Prefix in the "northbound" direction within
the BIER domain.
Given that the BIER information is associated with the prefix, the
BGP-LS Prefix Attribute TLV [I-D.ietf-idr-ls-distribution] can be
used to carry the BIER information. A new Prefix Attribute TLV and
Sub-TLV are defined for the encoding of BIER information.
3.1. The BIER TLV
A new Prefix Attribute TLV (defined in [I-D.ietf-idr-ls-distribution]
is defined for distributing BIER information. The new TLV is called
the BIER TLV. The BIER TLVs may appear multiple times.
The following BIER 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| reserved | subdomain-id | MT-ID | BSL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFR-id | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Sub-TLVs (variable) |
+- -+
| |
Figure 1
Type: TBD.
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Length: 2 octet.
Subdomain-id: Unique value identifying the BIER sub-domain, 1 octet.
MT-ID: Multi-Topology ID that identifies the topology that is
associated with the BIER sub-domain.1 octet.
BitString Length (BS Len): A 1 octet field encoding the supported
BitString length associated with this BFR-prefix.This field are
specified in section 3 of [I-D.ietf-bier-architecture].Given that the
bier router can support BSL values set, this field encoding the BSL
values set that BIER routers supported.
BFR-id: A 2 octet field encoding the BFR-id, as documented in
[I-D.ietf-bier-architecture]. If the BFR-id is zero, it means, the
advertising router is not advertising any BIER-id.
If multiple BIER Sub-TLVs are present, all having the same BS Length
and Subdomain-id values, first one MUST be used and subsequent ones
MUST be ignored.
3.1.1. The BIER MPLS Encapsulation Sub-TLV
The BIER MPLS Encapsulation Sub-TLV is a sub-TLV of the BIER TLV.
BIER MPLS Encapsulation Sub-TLV is used in order to advertise MPLS
specific information used for BIER. It MUST appear multiple times in
the BIER TLV as described in [I-D.ietf-bier-ospf-bier-extensions]
The following the BIER MPLS Encapsulation Sub-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Lbl Range Size | Label Range Base |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BS Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type: TBD.
Length: 2 octet.
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Label Range Size: A 1 octet field encoding the label range size of
the label range. It MUST be greater than 0, otherwise the TLV MUST
be ignored.
Label Range Base: A 3 octet field, where the 20 rightmost bits
represent the first label in the label range.
BS Length: Bitstring length for the label range that this router is
advertising per [I-D.ietf-bier-mpls-encapsulation]. 1 octet.The
values allowed in this field are specified in section 3 of
[I-D.ietf-bier-mpls-encapsulation].
The "label range" is the set of labels beginning with the label range
base and ending with (label range base)+(label range size)-1. A
unique label range is allocated for each BitStream length and Sub-
domain-ID. These label is used for BIER forwarding as described in
[I-D.ietf-bier-architecture] and
[I-D.ietf-bier-mpls-encapsulation].Label ranges within the sub-TLV
MUST NOT overlap, otherwise the whole sub-TLV MUST be disregarded
BS length in multiple BIER MPLS Encapsulation Sub-TLV inside the same
BIER Sub-TLV MUST NOT repeat, otherwise only the first BIER MPLS
Encapsulation Sub-TLV with such BS length MUST be used and any
subsequent BIER MPLS Encapsulation Sub-TLVs with the same BS length
MUST be ignored.
3.2. The BIER-TE TLV
This TLV is used to collect BIER-TE information in the "northbound"
direction within the BIER-TE domain.
The section will be added in next version.
4. IANA Considerations
This document requests assigning code-points from the registry for
the new Prefix Attribute TLV and Sub-TLV.
+-------------------+---------------+-----------------+
| TLV Code Point | Description | Value defined |
+-------------------+---------------+-----------------+
| 1158( recommend ) | BIER | this document |
+-------------------+---------------+-----------------+
Table 1: The new Prefix Attribute TLV
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+-----------------+-------------------------------+-----------------+
| Sub-TLV | Description | Value |
| Code Point | | |
+-----------------+-------------------------------+-----------------+
| 1 ( recommend) | BIER MPLS Encapsulation | this document |
+------------+-------------------------------+----------------------+
Table 2: The new Prefix Attribute Sub-TLV
5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See [RFC6952] for details.
6. Acknowledgements
We would like to thank Peter Psenak (Cisco) for his comments and
support of this work.
7. Normative references
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., P, T., and S.
Aldrin, "Multicast using Bit Index Explicit Replication",
draft-ietf-bier-architecture-03 (work in progress),
January 2016.
[I-D.ietf-bier-isis-extensions]
Ginsberg, L., P, T., Aldrin, S., and J. Zhang, "BIER
support via ISIS", draft-ietf-bier-isis-extensions-01
(work in progress), October 2015.
[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and
S. Aldrin, "Encapsulation for Bit Index Explicit
Replication in MPLS Networks", draft-ietf-bier-mpls-
encapsulation-03 (work in progress), February 2016.
[I-D.ietf-bier-ospf-bier-extensions]
Psenak, P., Kumar, N., Wijnands, I., Dolganow, A., P, T.,
Zhang, J., and S. Aldrin, "OSPF Extensions For BIER",
draft-ietf-bier-ospf-bier-extensions-01 (work in
progress), October 2015.
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[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-13
(work in progress), October 2015.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<http://www.rfc-editor.org/info/rfc3630>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>.
Authors' Addresses
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
Vengada Prasad Govindan
Cisco
Email: venggovi@cisco.com
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IJsbrand Wijnands
Cisco
De Kleetlaan 6a
Diegem 1831
Belgium
Email: ice@cisco.com
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