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Versions: 00 01 02                                                      
Network Working Group                                          A. Azimov
Internet-Draft                                              E. Bogomazov
Intended status: Standards Track                             Qrator Labs
Expires: May 18, 2017                                            R. Bush
                                               Internet Initiative Japan
                                                                K. Patel
                                                               K. Sriram
                                                                 US NIST
                                                       November 14, 2016

       New definition of ISP internal eBGP border using BGP Roles


   This document proposes a new definition of ISP borders using BGP
   Roles.  It may be used to improve the BGP best path selection
   algorithm for better support of hot-potato routing between different
   internal ASNs of an ISP.  It may also be used to enable transmission
   of local attributes between different internal ASNs of an ISP.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   be interpreted as described in RFC 2119 [RFC2119] only when they
   appear in all upper case.  They may also appear in lower or mixed
   case as English words, without normative meaning.

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
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 18, 2017.

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Copyright Notice

   Copyright (c) 2016 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Changes in BGP decision process . . . . . . . . . . . . . . .   3
   3.  Local Attributes Transmission . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The BGP best path selection algorithm (Section of [RFC4271])
   has a very clear definition of a network border: different ASNs -
   different networks.  It differs from some real world situations when
   two networks become one business entity and want to operate as one

   Today BGP does not provide any robust or automated support for such
   merging networks:

   o  There is no support for carrying local attributes through this

   o  Hot-potato routing, implemented by eBGP being preferred to iBGP,
      does not work, and

   o  Route Leak prevention inside such a united network can not be
      easily automated.

   In [I-D.ymbk-idr-bgp-open-policy] BGP Roles were introduced - a
   configuration option that strongly enforces agreement on real-world
   business relations between two BGP speakers.  This configuration
   option can accept values of: Peering, Customer, Provider, Internal,

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   and Complex.  These values could be used in a new ISP border
   definition: Internal vs. External.  With this definition of network
   borders, it becomes easy to allow robust propagation of local
   attributes between different ASNs of one ISP.  It could be also used
   to improve the hot-potato routing mechanism: where routes learned
   from External BGP connections should be preferred over Internal, even
   those which cross the ISP's internal AS/AS boundary.

2.  Changes in BGP decision process

   To improve hot-potato routing for networks with multiple ASNs we
   propose to replace step d) in Section of [RFC4271] with the

   If at least one of the candidate routes was received via a BGP
   session with External (Peer, Provider, Customer) role, remove from
   consideration all routes that were received via BGP sessions with an
   Internal role.

   While this step will improve traffic control for ISPs with multiple
   ASNs it will have no affect on ISPs with single ASN.

3.  Local Attributes Transmission

   Propagation of local attributes through an ISP's internal AS/AS
   border could be enabled only if both sides set Internal roles in
   their BGP Open negotiation.  Different attributes may still have
   different transmission policy:

   o  iOTC attribute from [I-D.ymbk-idr-bgp-open-policy] MUST be sent to
      enforce route leak prevention,

   o  LOCAL_PREF attribute MAY be sent, and

   o  MED attribute MAY be sent without changes.

4.  IANA Considerations

   This document has no IANA actions.

5.  Normative References

              Azimov, A., Bogomazov, E., and R. Bush, "Route Leak
              Detection and Filtering using Roles in Update and Open
              messages", draft-ymbk-idr-bgp-open-policy-00 (work in
              progress), March 2016.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,

Authors' Addresses

   Alexander Azimov
   Qrator Labs

   Email: aa@qrator.net

   Eugene Bogomazov
   Qrator Labs

   Email: eb@qrator.net

   Randy Bush
   Internet Initiative Japan

   Email: randy@psg.com

   Keyur Patel

   Email: keyurpat@yahoo.com

   Kotikalapudi Sriram

   Email: ksriram@nist.gov

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