Enhanced Route Refresh Capability for BGP-4
draft-ietf-idr-bgp-enhanced-route-refresh-01
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (idr WG) | |
|---|---|---|---|
| Authors | Keyur Patel , Enke Chen , Balaji Venkatachalapathy | ||
| Last updated | 2011-12-16 (Latest revision 2011-06-02) | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text htmlized pdfized bibtex | ||
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draft-ietf-idr-bgp-enhanced-route-refresh-01
Network Working Group K. Patel
Internet Draft E. Chen
Intended Status: Standards Track B. Venkatachalapathy
Expiration Date: June 17, 2012 Cisco Systems
December 16, 2011
Enhanced Route Refresh Capability for BGP-4
draft-ietf-idr-bgp-enhanced-route-refresh-01.txt
Status of this Memo
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draft-ietf-idr-bgp-enhanced-route-refresh-01.txt
Abstract
In this document we enhance the existing BGP route refresh mechanisms
to provide for the demarcation of the beginning and the ending of a
route refresh. The enhancement can be used to facilitate on-line,
non-disruptive consistency validations of BGP routing updates.
1. Introduction
It is sometimes necessary to perform routing consistency validations
such as checking for possible missing withdraws between BGP speakers
[RFC4271]. Currently such validations typically involve off-line,
manual operations which can be tedious and time consuming.
In this document we enhance the existing BGP route refresh mechanisms
[RFC2918] to provide for the demarcation of the beginning and the
ending of a route refresh (which refers to the complete re-
advertisement of the Adj-RIB-Out to a peer, subject to routing
policies). The enhancement can be used to facilitate on-line, non-
disruptive consistency validation of BGP routing updates.
1.1. Specification of Requirements
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].
2. Protocol Extensions
The BGP protocol extensions introduced in this document include the
definition of a new BGP capability, named "Enhanced Route Refresh
Capability", and the specification of the message subtypes for the
ROUTE-REFRESH message.
2.1. Enhanced Route Refresh Capability
The "Enhanced Route Refresh Capability" is a new BGP capability
[RFC5492]. The Capability Code for this capability is specified in
the IANA Considerations section of this document. The Capability
Length field of this capability is zero.
By advertising this capability to a peer, a BGP speaker conveys to
the peer that the speaker supports the message subtypes for the
ROUTE-REFRESH message and the related procedures described in this
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document.
2.2. Subtypes for ROUTE-REFRESH Message
The "Reserved" field of the ROUTE-REFRESH message specified in
[RFC2918] is re-defined as the "Message Subtype" with the following
values:
0 - Normal route refresh request [RFC2918]
with/without ORF [RFC5291]
1 - Demarcation of the beginning of a route refresh
2 - Demarcation of the ending of a route refresh
The use of the message subtypes is described in the Operations
section.
3. Operations
A BGP speaker that support the message subtypes for the ROUTE-REFRESH
message and the related procedures SHOULD advertise the "Enhanced
Route Refresh Capability".
The following procedures are applicable only if a BGP speaker has
received the "Enhanced Route Refresh Capability" from a peer.
Before the speaker starts a route refresh that is either initiated
locally, or in response to a "normal route refresh request" from the
peer, the speaker MUST send a ROUTE-REFRESH message with the
specified message subtype to mark the beginning of the route refresh.
After the speaker completes the re-advertisement of the entire Adj-
RIB-Out to the peer, it MUST send a ROUTE-REFRESH message with the
specified message subtype to mark the ending of the route refresh.
Conceptually the "entire ADJ-RIB-Out" for a peer in this section
refers to all the route entries in the "ADJ-RIB-Out" for the peer at
the start of the route refresh. When a route entry in the "ADJ-RIB-
Out" changes, the advertisement of the modified route entry (instead
of the snapshot entry) would suffice.
In processing a ROUTE-REFRESH message from a peer, the BGP speaker
MUST examine the "message subtype" field of the message and take the
appropriate actions. The BGP speaker SHALL use the demarcations of
the beginning and the ending of a route refresh to perform
consistency validations of the updates received from the peer. All
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the routes that were not re-advertised in the route refresh MUST be
purged, and SHOULD be logged for further analysis.
4. Error Handling
This document defines a new NOTIFICATION error code:
Error Code Symbolic Name
<TBD> ROUTE-REFRESH Message Error
The following error subcodes are defined as well:
Subcode Symbolic Name
1 Invalid Message Length
The error handling specified in this section is applicable only when
a BGP speaker has received the "Enhanced Route Refresh Capability"
from a peer.
When the BGP speaker detects an error while processing a ROUTE-
REFRESH message with a non-zero "Message Subtype" field, it MUST send
a NOTIFICATION message with Error Code "ROUTE-REFRESH Message Error".
The Data field of the NOTIFICATION message MUST contain the complete
ROUTE-REFRESH message.
If the length, excluding the fixed-size message header, of the ROUTE-
REFRESH message with Message Subtype 1 and 2 is not 4, then the error
subcode is set to "Invalid Message Length".
5. IANA Considerations
This document defines the Enhanced Route Refresh Capability for BGP.
The Capability Code 70 has been assigned by the IANA.
In addition, this document defines an NOTIFICATION error code and
several error subcodes for the ROUTE-REFRESH message. They need to
be registered with the IANA.
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6. Security Considerations
This extension to BGP does not change the underlying security issues.
7. Acknowledgments
The authors would like to thank Pedro Marques, Pradosh Mohapatra,
Robert Raszuk, Pranav Mehta, and Shyam Sethuram for discussions and
review. The authors would like to thank Martin Djernaes, Jeff haas,
Ilya Varlashkin, Rob Shakir, Paul Jakma, Jie Dong, Qing Zeng, Albert
Tian, and Jakob Heitz for their review and comments.
8. Normative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, January
2006.
[RFC2918] Chen, E., "Route Refresh Capability for BGP-4",
RFC 2918, September 2000.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, February 2009.
[RFC5291] Chen, E., and Rekhter, Y., "Outbound Route Filtering
Capability for BGP-4", RFC 5291, August 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9. Authors' Addresses
Keyur Patel
Cisco Systems
Email: keyupate@cisco.com
Enke Chen
Cisco Systems
Email: enkechen@cisco.com
Balaji Venkatachalapathy
Cisco Systems
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Email: bvenkata@cisco.com
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