Inter-Domain Routing P. Lapukhov
Internet-Draft Facebook
Intended status: Standards Track March 12, 2016
Expires: September 13, 2016
Use of BGP for dissemination of ILA mapping information
draft-lapukhov-bgp-ila-afi-00
Abstract
Identifier-Locator Addressing [I-D.herbert-nvo3-ila] relies on
splitting the 128-bit IPv6 address into identifier and locator parts
to implement identifier mobility, and network virtualization. This
document proposes a method for distributing the identifier to locator
mapping information using Multiprotocol Extensions for BGP-4
[RFC4760].
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].
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 13, 2016.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BGP ILA AFI . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Capability Advertisement . . . . . . . . . . . . . . . . . . 3
4. Disseminating Identifier-Locator mapping information . . . . 3
4.1. Advertising ILA mapping information . . . . . . . . . . . 3
4.2. Withdrawing ILA mapping information . . . . . . . . . . . 3
5. Interpreting the mapping information . . . . . . . . . . . . 4
5.1. Unicast SAFI . . . . . . . . . . . . . . . . . . . . . . 4
5.2. Multicast SAFI . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Manageability Considerations . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Under the ILA proposal, the IPv6 address is split in 64-bit
identifier (lower address bits) and locator (higher address bits)
portions. The locator part is determined from a mapping table that
maintains associations between the location-independent identifiers
and topologically significant locators. The hosts that collectively
implement and maintain such mappings are referred to as "ILA domain"
in this document. This document proposes a new address family
identifier (AFI) for the purpose of disseminating the locator-
identifier mappings among the nodes participating in the ILA domain.
2. BGP ILA AFI
This document introduces a new AFI known as a "Identifier-Locator
AFI" with the actual value to be assigned by IANA. The purpose of
this AFI is disseminating the mapping information between identifiers
and locators in ILA domain. This document defines the use of SAFI
values of "1" (unicast) and "2" (multicast) only.
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3. Capability Advertisement
A BGP speaker that wishes to exchange ILA mapping information MUST
use the Multiprotocol Extensions Capability Code, as defined in
[RFC4760], to advertise the corresponding AFI/SAFI pair.
4. Disseminating Identifier-Locator mapping information
4.1. Advertising ILA mapping information
For the purpose of ILA mapping encoding, the 8-octet locator field
SHALL be encoded in the "next-hop address" field. The "length of the
next-hop address" MUST be set to "8" (64-bit). The identifiers bound
to the locator SHALL be encoded within the NLRI portion of
MP_REACH_NLRI attribute. The NLRI portion of MP_REACH_NLRI starts
with the two-octet "Length of identifiers" field. The rest of the
NLRI is a collection of 8-octet (64-bit) identifiers that are bound
to the locator specified in the "next-hop address" field.
+---------------------------------------------------------+
| Address Family Identifier (2 octets) |
+---------------------------------------------------------+
| Subsequent Address Family Identifier (1 octet) |
+---------------------------------------------------------+
| Length of Next Hop Address (1 octet, set to "8") |
+---------------------------------------------------------+
| Locator value (8 octets) |
+---------------------------------------------------------+
| Reserved (1 octet), must be zero |
+---------------------------------------------------------+
| Length of identifiers field (2 octets, multiple of 8) |
+---------------------------------------------------------+
| Identifiers (variable, 8 octets each) |
+---------------------------------------------------------+
Figure 1: MP_REACH_NLRI Layout
4.2. Withdrawing ILA mapping information
Withdrawal of ILA mapping information is performed via an
MP_UNREACH_NLRI attribute advertisement organized as following:
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+---------------------------------------------------------+
| Address Family Identifier (2 octets) |
+---------------------------------------------------------+
| Subsequent Address Family Identifier (1 octet) |
+---------------------------------------------------------+
| Length of witdrawn identifiers (2 octets) |
+---------------------------------------------------------+
| Identifiers (variable, 8 octets each) |
+---------------------------------------------------------+
Figure 2: MP_UNREACH_NLRI Layout
5. Interpreting the mapping information
5.1. Unicast SAFI
Only the locator part of ILA address is used for packet routing, and
every node that hosts an identifier MUST have a unique routable /64
prefix within the scope of the ILA domain. The identifiers
advertised under the ILA AFI are expected to be used by the data-
plane implementation to perform match on a full IPv6 address and
decide whether the locator portion of the address needs a re-write.
It is up to the implementation to decide which full 128-bit IPv6
addresses need a rewrite, e.g. by matching on a Standard Identifier
Representation (SIR) prefix as defined in [I-D.herbert-nvo3-ila].
The locator rewrite information comes from the next-hop "address"
associated with the identifier. The next-hop field of MP_REACH_NLRI
attribute MUST NOT be used for any routing resolutions/lookups by the
BGP process itself. It should be used purely to create a rewrite
rule in the data-plane forwarding table. The actual forwarding
decision is then based on subsequent lookup in the forwarding table
to find the next hop to send the packet to.
5.2. Multicast SAFI
For multicast packets, the RPF check process SHALL be modified for
use with ILA source addresses. Specifically, source ILA IPv6
addresses with the identifier portion matching the mapping table
SHALL be mapped to proper locator, prior to performing the RPF check.
The ILA source addresses need to be identified by some means specific
to ILA implementation, e.g. by matching on configured SIR prefixes.
The ILA addresses that do not match any mapping entry SHALL be
considered as failing the RPF check.
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6. IANA Considerations
For the purpose of this work, IANA would be asked to allocate values
for the new AFI.
7. Manageability Considerations
TBD
8. Security Considerations
This document does not introduce any changes in terms of BGP
security. Defining ILA security model is outside of scope of this
document.
9. Acknowledgements
The author would like to thank Doug Porter for the initial idea
suggestion and discussion of this proposal.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[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,
<http://www.rfc-editor.org/info/rfc4271>.
[I-D.herbert-nvo3-ila]
Herbert, T., "Identifier-locator addressing for network
virtualization", draft-herbert-nvo3-ila-01 (work in
progress), October 2015.
10.2. Informative References
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>.
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Author's Address
Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
US
Email: petr@fb.com
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