Internet DRAFT - draft-dong-idr-one-time-ext-community-orf
draft-dong-idr-one-time-ext-community-orf
Network Working Group J. Dong
Internet-Draft Q. Zeng
Intended status: Standards Track Huawei Technologies
Expires: September 10, 2012 J. Heitz
Ericsson Inc.
K. Patel
Cisco Systems
R. Shakir
BT
March 9, 2012
One-time Extended Community Based Outbound Route Filter for BGP-4
draft-dong-idr-one-time-ext-community-orf-02
Abstract
This document defines a new Outbound Router Filter (ORF) type for
BGP, termed "One-time Extended Community Outbound Route Filter",
which would allow a BGP speaker to send to its BGP peer a route
refresh request with a set of extended-community-based filters to
make the peer re-advertise only the specific routes matching the
filters to the speaker. This ORF-type enables a BGP speaker to
refresh some specific routes without requiring its peer to re-
advertise the whole Adj-RIB-Out, which makes the route refresh
operation more efficient and reduces the impact on network stability.
This filter does not change the outbound route filters on BGP peers
and should only be used for one-time filtering.
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
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
working documents as Internet-Drafts. The list of current Internet-
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 10, 2012.
Copyright Notice
Copyright (c) 2012 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. One-time Extended Community ORF-Type . . . . . . . . . . . . . 5
3. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
7. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
The Outbound Route Filtering Capability defined in [RFC5291] provides
a mechanism for a BGP speaker to send to its BGP peer a set of
Outbound Route Filters (ORFs) that can be used by its peer to filter
its outbound routing updates to the speaker.
During some network operations, a BGP speaker only needs to retrieve
some routes with specific extended communities from its peer, but
sending plain ROUTE-REFRESH will lead to the peer re-advertising its
whole Adj-RIB-Out. Such a large amount of updates includes a lot of
unnecessary routes which would result in waste of processing
resources and bandwidth. With the increase of IPv6 deployment, this
problem could be more significant. Even configured with the ORF
mechanism as defined in [RFC5291], on receipt of a ROUTE-REFRESH
message, the peer will re-advertise all the routes matching the
current outbound route filters, i.e., the whole Adj-Rib-Out for this
BGP speaker. Since in this case the BGP speaker does not want to
change the outbound route filters on its peer, this requirement
cannot be met by the current ORF mechanism.
This document defines a new Outbound Router Filter (ORF) type for
BGP, termed "One-time Extended Community Outbound Route Filter",
which would allow a BGP speaker to send to its BGP peer a route
refresh request with a set of Extended Community based filters to
make the peer re-advertise only the specific routes matching the
filters to the speaker. This ORF-type enables a BGP speaker to
retrieve routes with specific Extended Communities without requiring
its peer to re-advertise the whole Adj-RIB-Out, which makes such
route refresh operation more efficient and also reduces the impact on
network stability. This filter does not change the outbound route
filters on BGP peers and should only be used for one-time filtering.
One use case of one-time Extended Community ORF would be to refresh
routes with specific Route Target (RT) Extended Community. For
example, on receipt of routes with specific RTs, according to local
policies some attributes of the routes may be changed, or some routes
may be discarded. When later such local policies are changed or
removed, the routes impacted by such policies need to be refreshed
and processed according to the new local policies. With the whole
Adj-RIB-Out route refresh it would result in a lot of unnecessary
routes being re-advertised, and this would be a waste of the
processing resource and bandwidth. In this case, one-time Extended
Community ORF would be quite useful to request only routes matching
specific RTs to be re-advertised.
Another use case is network maintenance or verification. During
maintenance, it may be revealed that some routes may be incorrect. A
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refresh of a small segment of the routing table can help to correct
those routes without requiring a refresh of the total routing table.
2. One-time Extended Community ORF-Type
This document defines a new ORF type: One-time Extended Community
ORF. Value of this ORF-Type is to be assigned by IANA.
In the following description, the sending speaker sends a one-time-
ORF request and the receiving speaker receives it and sends back the
routes to satisfy the request.
As specified in the [RFC5291], an ORF entry is a tuple of the form
<AFI/SAFI, ORF-Type, Action, Match, ORF-value>. An ORF consists of
one or more ORF entries that have a common AFI/SAFI and ORF-Type. An
ORF is identified by <AFI/SAFI, ORF-Type>.
The ORF entry consists of a single Extended Community, encoded as
either 8 octets [RFC4360], or 20 octets [RFC5701]. The encoding of
the type-specific part is as below:
+------------------------------------------+
| Ext-community Length (1 octet) |
+------------------------------------------+
| Ext-community value (8 or 20 octets) |
+------------------------------------------+
The "Ext-community Length" field contains length in octets of the
extended community in the "Ext-community value" field.
Since the semantics of this new ORF-Type is "one-time filtering" and
has no impact on existing ORFs, the Action field is irrelevant and
MUST be ignored on receipt.
The MATCH field of the One-time Extended Community ORF SHOULD be set
to PERMIT on the sender and SHOULD be ignored on the receiver. This
is the same as defined in Extended-Community ORF
[I-D.chen-bgp-ext-community-orf].
The ORF entries of this type would only be used as one-time filters
that MUST not change any previously installed ORF entry on the
receiving speaker.
3. Operations
The capability negotiation of <AFI/SAFI, One-time Extended Community
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ORF> MUST NOT delay the advertisement of routes with this AFI/SAFI.
The received One-time Extended Community ORF entries SHOULD only be
used for one-time route filtering and MUST NOT be saved locally. The
received One-time Extended Community ORF entries MUST NOT modify the
outbound route filters on the receiving speaker (either locally
configured or received from the sending speaker through ORF).
On receipt of ROUTE-REFRESH message with One-time Extended Community
ORF entries, the receiving speaker SHOULD re-advertise to the sending
speaker the routes from the Adj-RIB-Out associated with the sending
speaker which pass the entries carried in the One-time Extended
Community ORF as well as the locally saved ORFs (if any) received
from the sending speaker.
Since different processing orders may lead to different results, the
One-time-ORFs and the regular ORFs SHOULD not be encoded in one
ROUTE-REFRESH message.
During the period when the receiving speaker is sending updates to
satisfy the One-time-ORF request, it may experience other routing
activity that will require it to send updates unrelated to the One-
time-ORF request. It is permitted to send these updates before it
has completed sending the One-time-ORF related updates.
Similarly, if a route that passes the One-time-ORF has already been
sent and the receiving speaker experiences routing activity that
changes this route and the receiving speaker has not yet sent all
routes to satisfy the One-time-ORF request, it is permitted to send
the changed route immediately. A withdrawal of the route counts as a
valid change.
If the receiving speaker has received the Enhanced Route Refresh
Capability as described in [I-D.ietf-idr-bgp-enhanced-route-refresh],
then it SHALL perform the following additional procedures.
It SHALL send a ROUTE-REFRESH message with the subtype to indicate
demarcation of the beginning of route refresh (start-of-refresh)
before sending routes to satisfy the ORF request and send a ROUTE-
REFRESH message with the subtype to indicate demarcation of the
ending of route refresh (end-of-refresh) after sending all routes to
satisfy the request.
As part of the start-of-refresh and end-of-refresh messages, it SHALL
include the one-time-ORF rules that it is satisfying with this
refresh. The presence of the ORF is indicated in the same way as it
is with the normal route refresh as in [RFC5291]: A BGP speaker can
distinguish an incoming ROUTE-REFRESH message that carries one or
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more ORF entries from an incoming plain ROUTE-REFRESH message by
using the Message Length field in the BGP message header.
As with the procedures without the Enhanced Route Refresh Capability,
the receiving speaker is permitted to send updates for routes
unrelated to the ORF request before it has sent all updates to
satisfy the current ORF request.
If a receiving speaker receives a new one-time-ORF request before it
has finished completing a previous one, it MAY stop sending routes
for the previous ORF request. It MUST NOT send an end-of-refresh for
the previous request. If the speaker has received the Enhanced Route
Refresh Capability, it SHALL send a start-of-refresh for the new
request and start sending updates for it.
4. Security Considerations
This extension to BGP does not change the underlying security issues
in [RFC4271].
5. IANA Considerations
This document specifies a new Outbound Route Filtering (ORF) type,
One-time Extended Community ORF. The value of the ORF-type needs to
be assigned by IANA.
6. Acknowledgements
The authors would like to thank Robert Raszuk, John Scudder, Susan
Hares, Haibo Wang, Jiawei Dong, Yaqun Xiao, Mach Chen for their
valuable suggestions and comments to this document.
7. Normative References
[I-D.chen-bgp-ext-community-orf]
Chen, E., Lo, A., and K. Patel, "Extended Community Based
Outbound Route Filter for BGP-4",
draft-chen-bgp-ext-community-orf-02 (work in progress),
December 2011.
[I-D.ietf-idr-bgp-enhanced-route-refresh]
Patel, K., Chen, E., and B. Venkatachalapathy, "Enhanced
Route Refresh Capability for BGP-4",
draft-ietf-idr-bgp-enhanced-route-refresh-01 (work in
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progress), December 2011.
[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.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5291] Chen, E. and Y. Rekhter, "Outbound Route Filtering
Capability for BGP-4", RFC 5291, August 2008.
[RFC5701] Rekhter, Y., "IPv6 Address Specific BGP Extended Community
Attribute", RFC 5701, November 2009.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Building, No.3 Xinxi Rd
Beijing 100085
China
Email: jie.dong@huawei.com
Qing Zeng
Huawei Technologies
Huawei Building, No.3 Xinxi Rd
Beijing 100085
China
Email: zengqing@huawei.com
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Jakob Heitz
Ericsson Inc.
100 Headquarters Drive
San Jose, CA 95134
USA
Email: jakob.heitz@ericsson.com
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Rob Shakir
BT
London
UK
Email: rob.shakir@bt.com
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