Using Only Link-Local Address in Network Core
draft-behringer-lla-only-00

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Network Working Group                                       M. Behringer
Internet-Draft                                                 E. Vyncke
Intended status: BCP                                               Cisco
Expires: September 6, 2012                                 March 5, 2012

             Using Only Link-Local Address in Network Core
                      draft-behringer-lla-only-00

Abstract

   This document proposes to use only IPv6 link-local addresses on
   infrastructure links between routers, wherever possible.  It
   discusses the advantages and disadvantages of this approach to aide
   the decision process for a given network,

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
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   This Internet-Draft will expire on September 6, 2012.

Copyright Notice

   Copyright (c) 2012 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
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Behringer & Vyncke      Expires September 6, 2012               [Page 1]
Internet-Draft                lla-only-core                   March 2012

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . . . 3
   2.  Using Link-Local Address on Infrastructure Links  . . . . . . . 3
     2.1.  The Suggested Approach  . . . . . . . . . . . . . . . . . . 3
     2.2.  Advantages  . . . . . . . . . . . . . . . . . . . . . . . . 4
     2.3.  Caveats and Possible Workarounds  . . . . . . . . . . . . . 5
     2.4.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 5
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     5.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     5.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6

Behringer & Vyncke      Expires September 6, 2012               [Page 2]
Internet-Draft                lla-only-core                   March 2012

1.  Introduction

   An infrastructure link between a set of routers typically does not
   require global or even unique local addressing [RFC4193].  Using
   link-local addressing on such links has a number of advantages, for
   example that routing tables do not need to carry link addressing, and
   can therefore be significantly smaller.  This helps to decrease
   failover times in certain routing convergence events.  An interface
   of a router is also not reachable beyond the link boundaries,
   therefore reducing the attack horizon.

   We propose to configure neither globally routable IPv6 addresses nor
   unique local addresses on infrastructure links of routers, wherever
   possible.  We recommend to use exclusively link-local addresses on
   such links.

   This document discusses the advantages and caveats of this approach.

1.1.  Requirements Language

   In this document, the key words "MAY", "MUST, "MUST NOT", "OPTIONAL",
   "RECOMMENDED", "SHOULD", and "SHOULD NOT", are to be interpreted as
   described in RFC2119 [RFC2119].

2.  Using Link-Local Address on Infrastructure Links

   This document proposes to use only link-local addresses (LLA) on all
   router interfaces on infrastructure links.  Routers typically do not
   need to be reached from from users of the network, nor from outside
   the network.  For an network operator there may be reasons to send
   packets to an infrastructure link for certain monitoring tasks; we
   suggest that many of those tasks could also be handled differently,
   not requiring routable address space on infrastructure links.

2.1.  The Suggested Approach

   Neither global IPv6 addresses nor unique local addresses are
   configured on infrastructure links.  In the absence of specific
   global or unique local address definitions, the default behavior of
   routers is to use link-local addresses.
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