BGP Extensions for BIER
draft-xu-idr-bier-extensions-00
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| Document | Type |
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|---|---|---|---|
| Authors | Xiaohu Xu , Keyur Patel , Mach Chen , IJsbrand Wijnands | ||
| Last updated | 2015-02-16 | ||
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draft-xu-idr-bier-extensions-00
Network Working Group X. Xu
Internet-Draft Huawei
Intended status: Standards Track K. Patel
Expires: August 20, 2015 Cisco
M. Chen
Huawei
I. Wijnands
Cisco
February 16, 2015
BGP Extensions for BIER
draft-xu-idr-bier-extensions-00
Abstract
Bit Index Explicit Replication (BIER) is a new multicast forwarding
architecture which doesn't require an explicit tree-building protocol
and doesn't require intermediate routers to maintain any multicast
state. BIER is applicable in a multi-tenant data center network
envioronment for efficient delivery of Broadcast, Unknown-unicast and
Multicast (BUM) traffic while eliminating the need for maitaining a
huge amount of multicast state in an underlay. This document
describes BGP extensions for advertising the BIER-specific
information. These extesnions are applicable in those multi-tenant
data centers where BGP instead of IGP is deployed as an underlay for
network reachability advertisement. These extensions may also be
applicable in other scenarios.
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/.
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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 20, 2015.
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Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BIER Path Attribute . . . . . . . . . . . . . . . . . . . . . 3
4. Originating BIER Attribute . . . . . . . . . . . . . . . . . 4
5. Restrictions on Sending/Receiving . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Bit Index Explicit Replication (BIER)
[I-D.wijnands-bier-architecture] is a new multicast forwarding
architecture which doesn't require an explicit tree-building protocol
and doesn't require intermediate routers to maintain any multicast
state. BIER is applicable in a multi-tenant data center network
envioronment for efficient delivery of Broadcast, Unknown-unicast and
Multicast (BUM) traffic while eliminating the need for maitaining a
huge amount of multicast state in an
underlay[I-D.kumar-bier-use-cases]. This document describes BGP
extensions for advertising the BIER-specific information. More
specifically, in this document, we define a new optional, non-
transitive BGP attribute, referred to as the BIER attribute, to
convey the BIER-specific information such as BFR-ID, bitstring length
and so on. In addition, this document specifies procedures to
prevent the BIER attribute from "leaking out" of a BIER domain .
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These extensions are applicable in those multi-tenant data centers
where BGP instead of IGP is used as an underlay
[I-D.ietf-rtgwg-bgp-routing-large-dc]. These extensions may also be
applicable to other BGP based network scenarios.
1.1. 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].
2. Terminology
This memo makes use of the terms defined in [RFC4271].
3. BIER Path Attribute
This draft defines a new optional, transitive BGP path attribute,
referred to as the BIER attribute. This attribute can be attached to
a BGP UPDATE message by the originator so as to indicate the BIER-
specific information of a particular BFR which is identified by the
/32 or /128 address prefix contained in the NLRI.
The attribute type code for the BIER Attribute is TBD. The value
field of the BIER Attribute is defined here to contain a set of TLVs.
Each such TLV is encoded as shown in Figure 1.
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 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ~
| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..........................
Figure 1:BIER TLV
Type: A single octet encoding the TLV Type.
Length: A single octet encoding the length in octets of the TLV,
including the type and length fields. The length is encoded as an
unsigned binary integer. (Note that the minimum length is 3,
indicating that no value field is present.)
Value: A variable-length field containing zero or more octets.
This document defines three such TLVs including "BFR-ID TLV" , "BSL
TLV" and "MPLS BIER Encapsulation TLV". The first one is used to
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convey the BFR-ID of the BFR which is indicated by the NLRI. The
second one is used to indicate the BitString Length that the BFR
which is indicated by the NLRI can support. The third one is used to
indicate the MPLS label range available for the MPLS-BIER
encapsulation purpose [I-D.wijnands-mpls-bier-encapsulation]. Other
TLVs are to be defined in the future.
The BFR-ID TLV is encoded as follows:
Type:TBD2
Length:5
Value: contains a two-octet BFR-ID.
The BSL TLV is encoded as follows:
Type:TBD3
Length:4
Value: contains a one-octet BSL which indicates the length of the
Bitstring in 4-octets.
The BIER MPLS Encapsualtion TLV is encoded as follows:
Type:TBD4
Length:7
Value: contains a one-octet Label Range Size field indicating the
size of the label range, and a 3-octect Label Rang Base field
where the 20 rightmost bits represent the first label in the label
range.
4. Originating BIER Attribute
An implementation that supports the BIER attribute MUST support a
policy to enable or disable the creation of the BIER attribute and
its attachment to specific BGP routes. An implementation MAY disable
the creation of the BIER attribute unless explicitly configured to do
so otherwise. A BGP speaker MUST only attach the locally created
BIER attribute to a BGP UPDATE message in which one of its local
addresses (e.g., a loopback address) is contained in the NLRI.
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5. Restrictions on Sending/Receiving
An implementation that supports the BIER attribute MUST support a
per-EBGP-session policy, that indicates whether the attribute is
enabled or disabled for use on that session. The BIER attribute MUST
NOT be sent on any EBGP peers for which the session policy is not
configured. If an BIER attribute is received on a BGP session for
which session policy is not configured, then the received attribute
MUST be treated exactly as if it were an unrecognized non-transitive
attribute. That is, "it MUST be quietly ignored and not passed along
to other BGP peers".
To prevent the BIER attribute from "leaking out" of an BIER domain,
each BGP router on the BIER domain MUST support an outbound route
announcement policy.Such a policy MUST be disabled on each EBGP
session by default unless explicitly configured.
6. Acknowledgements
TBD.
7. IANA Considerations
IANA is requested to assign a codepoint in the "BGP Path Attributes"
registry to the BIER attribute. IANA shall create a registry for
"BGP BIER Attribute Types". The type field consists of a single
octet, with possible values from 1 to 255. (The value 0 is
"reserved".) The allocation policy for this field is to be
"Standards Action". Type codes should be allocated for BFR-ID TLV,
BSL TLV and BIER MPLS Encapsualtion TLV respectively.
8. Security Considerations
TBD.
9. References
9.1. Normative References
[I-D.wijnands-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-wijnands-bier-architecture-04 (work in
progress), February 2015.
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[I-D.wijnands-mpls-bier-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and
S. Aldrin, "Encapsulation for Bit Index Explicit
Replication in MPLS Networks", draft-wijnands-mpls-bier-
encapsulation-02 (work in progress), December 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
9.2. Informative References
[I-D.ietf-rtgwg-bgp-routing-large-dc]
Lapukhov, P., Premji, A., and J. Mitchell, "Use of BGP for
routing in large-scale data centers", draft-ietf-rtgwg-
bgp-routing-large-dc-01 (work in progress), February 2015.
[I-D.kumar-bier-use-cases]
Kumar, N., Asati, R., Chen, M., Xu, X., Dolganow, A.,
Przygienda, T., arkadiy.gulko@thomsonreuters.com, a., and
D. Robinson, "BIER Use Cases", draft-kumar-bier-use-
cases-02 (work in progress), February 2015.
Authors' Addresses
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
Keyur Patel
Cisco
Email: keyupate@cisco.com
Mach Chen
Huawei
Email: mach.chen@huawei.com
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IJsbrand Wijnands
Cisco
Email: ice@cisco.com
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