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Network Working Group                                         P. Francis
Internet-Draft                                                   MPI-SWS
Intended status: Informational                                     X. Xu
Expires: August 26, 2011                                          Huawei
                                                              H. Ballani
                                                              Cornell U.
                                                                  D. Jen
                                                                    UCLA
                                                               R. Raszuk
                                                                   Cisco
                                                                L. Zhang
                                                                    UCLA
                                                       February 22, 2011


               Auto-Configuration in Virtual Aggregation
                     draft-ietf-grow-va-auto-03.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.  An Extended Communities Attribute is used to convey to
   other routers that a given route can be FIB-suppressed.  This draft
   has no changes from the 02 draft.

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 August 26, 2011.

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 . . . . . . . . . . . . . . . . . . . . 4
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     5.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
     5.2.  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 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 an 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.  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 must assign type values for the Extended Communities Attributes
   that convey the tags.


4.  Security Considerations

   As of this writing, there are no known new security threats
   introduced by this draft.


5.  References

5.1.  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",



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              draft-ietf-grow-va-01 (work in progress), Oct 2009.

   [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.

5.2.  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


   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










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   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


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

   Phone:
   Email: lixia@cs.ucla.edu























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