Internet DRAFT - draft-ietf-idr-bgp-enhanced-route-refresh
draft-ietf-idr-bgp-enhanced-route-refresh
IDR K. Patel
Internet-Draft E. Chen
Updates: 2918 (if approved) Cisco Systems
Intended status: Standards Track B. Venkatachalapathy
Expires: December 11, 2014
June 9, 2014
Enhanced Route Refresh Capability for BGP-4
draft-ietf-idr-bgp-enhanced-route-refresh-10.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 correction
of BGP RIB inconsistencies in a non-disruptive manner. This document
updates RFC 2918.
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
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This Internet-Draft will expire on December 11, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 2
3.1. Enhanced Route Refresh Capability . . . . . . . . . . . . 3
3.2. Subtypes for ROUTE-REFRESH Message . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
It is sometimes necessary to perform routing consistency validations
such as checking for possible missing route withdrawals 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.
This document updates [RFC2918] by redefining a field in the ROUTE-
REFRESH message that was previously designated as Reserved.
2. 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 [RFC2119] only when
they appear in all upper case. They may also appear in lower or
mixed case as English words, without any normative meaning.
3. Protocol Extensions
The BGP protocol extensions introduced in this document include the
definition of a new BGP capability, named "Enhanced Route Refresh
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Capability", and the specification of the message subtypes for the
ROUTE-REFRESH message.
3.1. Enhanced Route Refresh Capability
The "Enhanced Route Refresh Capability" is a new BGP capability
[RFC5492]. IANA has assigned a Capability Code of 70 for this
capability . 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
document.
3.2. 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
(BoRR) operation.
2 - Demarcation of the ending of a route refresh
(EoRR) operation.
The remaining values of the message subtypes are reserved for future
use. The use of the new message subtypes is described in the
Operations section.
4. Operation
A BGP speaker that supports 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 BoRR message. After the speaker
completes the re-advertisement of the entire Adj-RIB-Out to the peer,
it MUST send an EoRR message.
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
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the start of the route refresh operation. These route entries
comprise both the reachability as well as unreachability information.
When a route entry in the "Adj-RIB-Out" changes, only the modified
route entry needs to be advertised.
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 message processing rules for ROUTE-REFRESH
message with subtype of 0 are described in [RFC2918] and [RFC5291].
A BGP speaker can receive a BoRR message from a peer at any time,
either as a result of a peer responding to a ROUTE-REFESH message, or
as a result of a peer unilaterally initiating a route refresh. When
a BGP speaker receives a BoRR message from a peer, it MUST mark all
the routes with the given Address Family Identifer and Subsequent
Address Family Identifier, <AFI, SAFI> [RFC2918] from that peer as
stale. As it receives routes from its peer's subsequent Adj-RIB-Out
re-advertisement, these replace any corresponding stale routes. When
a BGP speaker receives an EoRR message from a peer, it MUST
immediately remove any routes from the peer that are still marked as
stale for that <AFI, SAFI>. Such purged routes MAY be logged for
future analysis. A BGP speaker MAY ignore any EoRR message received
without a prior receipt of an associated BoRR message. Such messages
MAY be logged for future analysis.
An implementation MAY impose a locally configurable upper bound on
how long it would retain any stale routes. Once the upper bound is
reached, the implementation MAY remove any routes from the peer that
are still marked as stale for that <AFI, SAFI> without waiting for an
EoRR message.
The following procedures are specified in order to simplify the
interaction with the BGP Graceful Restart [RFC4724]. In particular,
these procedures ensure that End-of-RIB (EoR) defined in Graceful
Restart and EoRR as defined in this specification are kept separate,
thereby avoiding any premature cleanup of stale routes. For a BGP
speaker that supports the BGP Graceful Restart, it MUST NOT send a
BoRR for an <AFI, SAFI> to a neighbor before it sends the EoR for the
<AFI, SAFI> to the neighbor. A BGP speaker that has received the
Graceful Restart Capability from its neighbor, MUST ignore any BoRRs
for an <AFI, SAFI> from the neighbor before the speaker receives the
EoR for the given <AFI, SAFI> from the neighbor. The BGP speaker
SHOULD log an error of the condition for further analysis.
5. Error Handling
This document defines a new NOTIFICATION error code:
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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.
If the length, excluding the fixed-size message header, of the
received ROUTE-REFRESH message with Message Subtype 1 and 2 is not 4,
then the BGP speaker MUST send a NOTIFICATION message with the Error
Code of "ROUTE-REFRESH Message Error" and the subcode of "Invalid
Message Length". The Data field of the NOTIFICATION message MUST
contain the complete ROUTE-REFRESH message.
When the BGP speaker receives a ROUTE-REFRESH message with a "Message
Subtype" field other than 0, 1 or 2, it MUST ignore the received
ROUTE-REFRESH message. It SHOULD log an error for further analysis.
6. IANA Considerations
This document defines the Enhanced Route Refresh Capability for BGP.
The Capability Code 70 has been assigned by the IANA from the "BGP
Capability Codes" registry. IANA should update that registry entry
to reference this document when it is published as an RFC. This
document also defines two new subcodes for the Route Refresh message.
They need to be registered with the IANA. We request IANA to create
a new registry for the Route Refresh message subcodes as follows:
Under "Border Gateway Protocol (BGP) Parameters":
Registry: "BGP Route Refresh Subcodes"
Reference: [RFC-to-Be]
Registration Procedure(s): Values 0-127 Standards Action, values
128-254 First Come, First Served, Value 255 reserved
Value Code Reference
0 Route-Refresh [RFC2918], [RFC5291]
1 BoRR [RFC-to-Be]
2 EoRR [RFC-to-Be]
3-127 Unassigned
128-254 Unassigned
255 Reserved [RFC-to-Be]
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In addition, this document defines a NOTIFICATION error code and an
error subcode related to the ROUTE-REFRESH message. We request IANA
to allocate a new error code from the "BGP Error Codes" registry with
the symbolic name "ROUTE-REFRESH Message Error", referencing this
document. We request IANA to create a new registry for the error
subcodes as follows:
Under "BGP Error Subcodes":
Registry: "BGP ROUTE-REFRESH Message Error subcodes"
Reference: [RFC-to-Be]
Registration Procedure(s): Values 0-127 Standards Action, values
128-255 First Come, First Served
Value Code Reference
0 Reserved
1 Invalid Message Length [RFC-to-Be]
2-127 Unassigned
128-255 Unassigned
7. Security Considerations
Security considerations are given in [RFC4272] , but do not cover
Route-Refresh and many other BGP extensions. This draft does not
significantly change the underlying security issues regarding Route-
Refresh, although improved error handling may aid operational
security.
8. Acknowledgements
The authors would like to thank Pedro Marques, Pradosh Mohapatra,
Robert Raszuk, Pranav Mehta, Shyam Sethuram, Bruno Decraene, Martin
Djernaes, Jeff Haas, Ilya Varlashkin, Rob Shakir, Paul Jakma, Jie
Dong, Qing Zeng, Albert Tian, Jakob Heitz and Chris Hall for their
review and comments. The authors would like to thank John Scudder
for the review and contribution to this document.
9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2918] Chen, E., "Route Refresh Capability for BGP-4", RFC 2918,
September 2000.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
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[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", RFC
4272, January 2006.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
January 2007.
[RFC5291] Chen, E. and Y. Rekhter, "Outbound Route Filtering
Capability for BGP-4", RFC 5291, August 2008.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, February 2009.
Authors' Addresses
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Enke Chen
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: enkechen@cisco.com
Balaji Venkatachalapathy
Email: balaji_pv@hotmail.com
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