Network Working Group P. Francis
Internet-Draft MPI-SWS
Intended status: Informational X. Xu
Expires: January 2, 2012 Huawei
H. Ballani
Cornell U.
D. Jen
UCLA
R. Raszuk
Cisco
L. Zhang
UCLA
July 1, 2011
Auto-Configuration in Virtual Aggregation
draft-ietf-grow-va-auto-04.txt
Abstract
Virtual Aggregation as specified in [I-D.ietf-grow-va] requires
configuration of a static "VP-List" on all routers. The VP-List
allows routers to know which prefixes may or may not be FIB-
installed. This draft specified an optional method of determining
this that requires far less configuration. Specifically, it requires
the configuration of a "VP-Range" in ASBRs connected to transit and
peer ISPs. A Non-transitive Extended Communities Attribute is used
to convey to other routers that a given route can be FIB-suppressed.
Status of this Memo
This Internet-Draft is submitted to IETF 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/.
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
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 2, 2012.
Copyright Notice
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Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . . 3
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
As the current VA specification stands ([I-D.ietf-grow-va]), routers
have to know which prefixes they must FIB-install and which they need
not FIB-install. The VP-List tells them this: they must FIB-install
routes to Virtual Prefixes (VP), and they need not FIB-install routes
to prefixes that fall within VPs for which they are not an
Aggregation Point Router (APR). The same VP-List must be installed
in every router.
This draft specifies an optional alternative to the VP-List that
requires far less configuration. Specifically, a list of one or more
"VP-Ranges" is configured in ASBRs --- typically ASBRs that do not
connect to customer networks. These ASBRs then simply tag routes as
to whether the route can be suppressed. This is simpler than the
current configured VP-List approach in two regards. First, fewer
routers need to be configured. Second, the VP-Range is simpler than
the VP-List. In most cases, once an ISP is past its initial VA roll-
out phase, the VP-Range consists of a single 0/0 entry.
This draft uses terms defined in [I-D.ietf-grow-va].
1.1. Requirements notation
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. Specification
With the "VP-Range" approach to determining suppressability, certain
ASBRs are designated as "tagging routers". Tagging routers
explicitly tag routes with a Non-transitive Extended Communities
Attribute that indicates whether the route can be FIB-suppressed.
All ASBRs that connect to one or more transit provider ISPs MUST be
tagging routers. ASBRs that connect to one or more peer ISPs SHOULD
be tagging routers. ASBRs that connect to customer networks SHOULD
NOT be tagging routers.
Tagging routers are configured with a "VP-Range" list. This consists
of the ranges of IP address that are collectively covered by all VPs
in the AS. In a mature deployment of VA, the range would amount to
all IP addresses, in which case the VP-Range is simply 0/0. Early in
VA deployment, when an ISP is still in the testing or roll-out phase,
the VP-Range may consist of multiple entries.
Tagging routers SHOULD tag any route whose prefix falls within the
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VP-Range with a "can-suppress" tag, with the following exceptions:
1. Tagging routers MUST NOT tag VP routes with can-suppress (where a
VP route is that route to the VP that the router originates in
its role as an APR).
2. If the ISP has a policy of FIB-installing customer routes, then
routes received from customers SHOULD NOT be tagged with can-
suppress.
The can-suppress tag itself is an Extended Communities Attribute
[RFC4360] to be assigned by IANA from the "well-known" pool define in
[I-D.ietf-idr-reserved-extended-communities]. The Transitive Bit
MUST be set to value 1 (the community is non-transitive across ASes).
Routers install or suppress FIB entries according to the following
rules. Note that tagging routers conceptually follow these rules
after tagging (or not tagging) the route. Note also that these rules
apply only to the route used by the router as the best route. In
other words, if a router receives two routes for the same prefix, and
one route is tagged can-suppress and the other is not, the router
follows these rules only with respect to the route that it selects as
the best route.
1. Routes without the can-suppress tag MUST be FIB-installed.
2. APRs MUST FIB-install routes for sub-prefixes that fall within
the APR's VPs, whether or not the route is tagged can-suppress.
3. Otherwise, routers MAY FIB-suppress routes tagged as can-
suppress.
3. IANA Considerations
IANA is requested to assign, from the registry "BGP Assigned non-
transitive extended communities", a value TBD for "VA can suppress":
Registry Name: BGP Assigned non-transitive extended
communities
Name Type Value
---- ----------
VA can suppress TBD
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4. Security Considerations
As of this writing, there are no known new security threats
introduced by this draft.
5. Acknowledgements
The authors would like to thank Wes George and Bruno Decraene for
their reviews and suggestions.
6. References
6.1. Normative References
[I-D.ietf-grow-va]
Francis, P., Xu, X., Ballani, H., Jen, D., Raszuk, R., and
L. Zhang, "FIB Suppression with Virtual Aggregation",
draft-ietf-grow-va-04 (work in progress), Oct 2009.
[I-D.ietf-idr-reserved-extended-communities]
Decraene, B. and P. Francois, "Assigned BGP extended
communities",
draft-ietf-idr-reserved-extended-communities-01 (work in
progress), May 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
6.2. Informative References
Authors' Addresses
Paul Francis
Max Planck Institute for Software Systems
Gottlieb-Daimler-Strasse
Kaiserslautern 67633
Germany
Phone: +49 631 930 39600
Email: francis@mpi-sws.org
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Xiaohu Xu
Huawei Technologies
No.3 Xinxi Rd., Shang-Di Information Industry Base, Hai-Dian District
Beijing, Beijing 100085
P.R.China
Phone: +86 10 82836073
Email: xuxh@huawei.com
Hitesh Ballani
Cornell University
4130 Upson Hall
Ithaca, NY 14853
US
Phone: +1 607 279 6780
Email: hitesh@cs.cornell.edu
Dan Jen
UCLA
4805 Boelter Hall
Los Angeles, CA 90095
US
Phone:
Email: jenster@cs.ucla.edu
Robert Raszuk
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134
USA
Phone:
Email: raszuk@cisco.com
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Lixia Zhang
UCLA
3713 Boelter Hall
Los Angeles, CA 90095
US
Phone:
Email: lixia@cs.ucla.edu
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