Enterprise Multihoming using Provider-Assigned Addresses without Network Prefix Translation: Requirements and Solution
draft-ietf-rtgwg-enterprise-pa-multihoming-00

Document Type Active Internet-Draft (rtgwg WG)
Last updated 2017-03-13
Replaces draft-bowbakova-rtgwg-enterprise-pa-multihoming
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Routing Working Group                                           F. Baker
Internet-Draft                                             Cisco Systems
Intended status: Informational                                 C. Bowers
Expires: September 14, 2017                             Juniper Networks
                                                              J. Linkova
                                                                  Google
                                                          March 13, 2017

Enterprise Multihoming using Provider-Assigned Addresses without Network
             Prefix Translation: Requirements and Solution
             draft-ietf-rtgwg-enterprise-pa-multihoming-00

Abstract

   Connecting an enterprise site to multiple ISPs using provider-
   assigned addresses is difficult without the use of some form of
   Network Address Translation (NAT).  Much has been written on this
   topic over the last 10 to 15 years, but it still remains a problem
   without a clearly defined or widely implemented solution.  Any
   multihoming solution without NAT requires hosts at the site to have
   addresses from each ISP and to select the egress ISP by selecting a
   source address for outgoing packets.  It also requires routers at the
   site to take into account those source addresses when forwarding
   packets out towards the ISPs.

   This document attempts to define a complete solution to this problem.
   It covers the behavior of routers to forward traffic taking into
   account source address, and it covers the behavior of host to select
   appropriate source addresses.  It also covers any possible role that
   routers might play in providing information to hosts to help them
   select appropriate source addresses.  In the process of exploring
   potential solutions, this documents also makes explicit requirements
   for how the solution would be expected to behave from the perspective
   of an enterprise site network administrator .

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

Baker, et al.          Expires September 14, 2017               [Page 1]
Internet-Draft          Enterprise PA Multihoming             March 2017

   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 September 14, 2017.

Copyright Notice

   Copyright (c) 2017 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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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Enterprise Multihoming Requirements . . . . . . . . . . . . .   6
     2.1.  Simple ISP Connectivity with Connected SERs . . . . . . .   6
     2.2.  Simple ISP Connectivity Where SERs Are Not Directly
           Connected . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.3.  Enterprise Network Operator Expectations  . . . . . . . .   8
     2.4.  More complex ISP connectivity . . . . . . . . . . . . . .  11
     2.5.  ISPs and Provider-Assigned Prefixes . . . . . . . . . . .  13
     2.6.  Simplified Topologies . . . . . . . . . . . . . . . . . .  14
   3.  Generating  Source-Prefix-Scoped Forwarding Tables  . . . . .  14
   4.  Mechanisms For Hosts To Choose Good Source Addresses In A
       Multihomed Site . . . . . . . . . . . . . . . . . . . . . . .  21
     4.1.  Source Address Selection Algorithm on Hosts . . . . . . .  23
     4.2.  Selecting Source Address When Both Uplinks Are Working  .  26
       4.2.1.  Distributing Address Selection Policy Table with
               DHCPv6  . . . . . . . . . . . . . . . . . . . . . . .  26
       4.2.2.  Controlling Source Address Selection With Router
               Advertisements  . . . . . . . . . . . . . . . . . . .  26
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