Source-Address-Dependent Routing and Source Address Selection for IPv6 Hosts: Overview of the Problem Space
RFC 8043

Document Type RFC - Informational (January 2017; No errata)
Last updated 2017-01-06
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Independent Submission                                       B. Sarikaya
Request for Comments: 8043                                    Huawei USA
Category: Informational                                     M. Boucadair
ISSN: 2070-1721                                                   Orange
                                                            January 2017

     Source-Address-Dependent Routing and Source Address Selection
             for IPv6 Hosts: Overview of the Problem Space

Abstract

   This document presents the source-address-dependent routing (SADR)
   problem space from the host's perspective.  Both multihomed hosts and
   hosts with multiple interfaces are considered.  Several network
   architectures are presented to illustrate why source address
   selection and next-hop resolution are needed in view of
   source-address-dependent routing.

   The document is scoped on identifying a set of scenarios for
   source-address-dependent routing from the host's perspective and
   analyzing a set of solutions to mitigate encountered issues.  The
   document does not make any solution recommendations.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8043.

Sarikaya & Boucadair          Informational                     [Page 1]
RFC 8043            Source-Address-Dependent-Routing        January 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
   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Overall Context . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Source-Address-Dependent Routing (SADR) Scenarios . . . . . .   4
     2.1.  Multi-Prefix Multihoming  . . . . . . . . . . . . . . . .   5
     2.2.  Multi-Prefix Multi-Interface  . . . . . . . . . . . . . .   5
     2.3.  Home Network (Homenet)  . . . . . . . . . . . . . . . . .   7
     2.4.  Service-Specific Egress Routing . . . . . . . . . . . . .   7
   3.  Analysis of Source-Address-Dependent Routing  . . . . . . . .   8
     3.1.  Scenarios Analysis  . . . . . . . . . . . . . . . . . . .   8
     3.2.  Provisioning Domains and SADR . . . . . . . . . . . . . .  10
   4.  Discussion of Alternate Solutions . . . . . . . . . . . . . .  11
     4.1.  Router Advertisement Option . . . . . . . . . . . . . . .  11
     4.2.  Router Advertisement Option Set . . . . . . . . . . . . .  12
     4.3.  Rule 5.5 for Source Address Selection . . . . . . . . . .  12
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

Sarikaya & Boucadair          Informational                     [Page 2]
RFC 8043            Source-Address-Dependent-Routing        January 2017

1.  Introduction

1.1.  Overall Context

   BCP 38 recommends ingress traffic filtering to prohibit Denial-of-
   Service (DoS) attacks.  As such, datagrams with source addresses that
   do not match with the network where the host is attached are
   discarded [RFC2827].  Preventing packets from being dropped due to
   ingress filtering is difficult, especially in multihomed networks
   where the host receives more than one prefix from the networks it is
   connected to, and consequently may have more than one source address.
   Based on BCP 38, BCP 84 introduced recommendations on the routing
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