Current Practices for Multiple-Interface Hosts
RFC 6419

Internet Engineering Task Force (IETF)                      M. Wasserman
Request for Comments: 6419                        Painless Security, LLC
Category: Informational                                         P. Seite
ISSN: 2070-1721                                  France Telecom - Orange
                                                           November 2011

             Current Practices for Multiple-Interface Hosts

Abstract

   An increasing number of hosts are operating in multiple-interface
   environments.  This document summarizes current practices in this
   area and describes in detail how some common operating systems cope
   with challenges that ensue from this context.

Status of This Memo

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

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   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/rfc6419.

Copyright Notice

   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
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   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.

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RFC 6419                  MIF Current Practices            November 2011

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Summary of Current Approaches  . . . . . . . . . . . . . . . .  3
     2.1.  Centralized Connection Management  . . . . . . . . . . . .  3
     2.2.  Per-Application Connection Settings  . . . . . . . . . . .  4
     2.3.  Stack-Level Solutions to Specific Problems . . . . . . . .  4
       2.3.1.  DNS Resolution Issues  . . . . . . . . . . . . . . . .  5
       2.3.2.  First-Hop Selection  . . . . . . . . . . . . . . . . .  5
       2.3.3.  Address Selection Policy . . . . . . . . . . . . . . .  5
   3.  Current Practices in Some Operating Systems  . . . . . . . . .  6
     3.1.  Mobile Handset Operating Systems . . . . . . . . . . . . .  6
       3.1.1.  Nokia S60 3rd Edition, Feature Pack 2  . . . . . . . .  7
       3.1.2.  Microsoft Windows Mobile and Windows Phone 7 . . . . .  9
       3.1.3.  RIM BlackBerry . . . . . . . . . . . . . . . . . . . . 10
       3.1.4.  Google Android . . . . . . . . . . . . . . . . . . . . 11
       3.1.5.  Qualcomm Brew  . . . . . . . . . . . . . . . . . . . . 12
       3.1.6.  Leadcore Technology Arena  . . . . . . . . . . . . . . 13
     3.2.  Desktop Operating Systems  . . . . . . . . . . . . . . . . 14
       3.2.1.  Microsoft Windows  . . . . . . . . . . . . . . . . . . 14
         3.2.1.1.  First-Hop Selection  . . . . . . . . . . . . . . . 14
         3.2.1.2.  Outbound and Inbound Addresses . . . . . . . . . . 14
         3.2.1.3.  DNS Configuration  . . . . . . . . . . . . . . . . 15
       3.2.2.  Linux and BSD-Based Operating Systems  . . . . . . . . 16
         3.2.2.1.  First-Hop Selection  . . . . . . . . . . . . . . . 16
         3.2.2.2.  Outbound and Inbound Addresses . . . . . . . . . . 16
         3.2.2.3.  DNS Configuration  . . . . . . . . . . . . . . . . 17
   4.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   6.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 19
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 19
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 19

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1.  Introduction

   Multiple-interface hosts face several challenges not faced by single-
   interface hosts, some of which are described in the multiple