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Network Working Group                                         P. Francis
Internet-Draft                                                   MPI-SWS
Intended status: Informational                                     X. Xu
Expires: July 2, 2012                                             Huawei
                                                              H. Ballani
                                                              Cornell U.
                                                                  D. Jen
                                                                    UCLA
                                                          R. Raszuk, Ed.
                                                            NTT MCL Inc.
                                                                L. Zhang
                                                                    UCLA
                                                       December 30, 2011


               Auto-Configuration in Virtual Aggregation
                     draft-ietf-grow-va-auto-05.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
   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
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 2, 2012.

Copyright Notice




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   Copyright (c) 2011 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


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 (editor)
   NTT MCL Inc.
   101 S Ellsworth Avenue Suite 350
   San Mateo, CA  94401
   US

   Email: robert@raszuk.net


   Lixia Zhang
   UCLA
   3713 Boelter Hall
   Los Angeles, CA  90095
   US

   Phone:
   Email: lixia@cs.ucla.edu




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