Sending Solicited RAs Unicast
draft-yc-v6ops-solicited-ra-unicast-00

IPv6 Operations                                           A. Yourtchenko
Internet-Draft                                                     cisco
Intended status: Best Current Practice                        L. Colitti
Expires: January 7, 2016                                          Google
                                                            July 6, 2015

                     Sending Solicited RAs Unicast
                 draft-yc-v6ops-solicited-ra-unicast-00

Abstract

   On links with a large number of mobile devices, sending Solicited
   Router Advertisement as multicast packets can severely impact host
   power consumption.  This document recommends that on such network,
   RAs be sent unicast.

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 January 7, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Consequences  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     7.2.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

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

   On links with a large number of mobile devices, sending solicited
   Router Advertisements as multicast packets can severely impact host
   power consumption.  This is because every time a device joins the
   network, all devices on the network receive a multicast Router
   Advertisement.  In the worst case, if devices are continually joining
   and leaving the network, and the network is large enough, then all
   devices on the network will receive solicited Router Advertisements
   at the maximum rate specified by section 6.2.6 of [RFC4861], which is
   one every 3 seconds.

2.  Consequences

   Observed host reactions to this include:

   o  Some hosts simply experience bad battery life on these networks
      and otherwise operate normally.  This is frustrating for users of
      these networks.

   o  Some hosts react by dropping all Router Advertisement packets when
      in power saving mode on any network, e.g., [1].  This causes
      devices to lose connectivity when in power-saving mode,
      potentially disrupting background network communications, because
      the device is no longer able to send packets or acknowledge
      received traffic.

   o  Some hosts react by dropping *all* IPv6 packets when in power
      saving mode, [2].  This disrupts network communications.

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   Compounding the problem, when dealing with devices that drop Router
   Advertisements when in power saving mode, some network administrators
   work around the problem by sending RAs even more frequently.  This
   causes devices to engage in even more aggressive filtering.

3.  Recommendations

   Router manufacturers SHOULD allow network administrators to configure
   the routers to respond to Router Solicitations with unicast Router
   Advertisements.

   Networks that serve large numbers (tens or hundreds) of mobile
   devices SHOULD enable this behaviour.

   No protocol changes are required, since responding to Router
   Solicitations with unicast Router Advertisements is already allowed
   by section 6.2.4 of [RFC4861].

4.  Acknowledgements

5.  IANA Considerations

   None.

6.  Security Considerations

   Not discussed in -00.

7.  References

7.1.  Normative References

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

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

7.2.  URIs

   [1] https://code.google.com/p/android/issues/detail?id=32662

   [2] http://www.gossamer-threads.com/lists/nsp/ipv6/54641

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Authors' Addresses

   Andrew Yourtchenko
   cisco
   7a de Kleetlaan
   Diegem, 1831
   Belgium

   Phone: +32 2 704 5494
   Email: ayourtch@cisco.com

   Lorenzo Colitti
   Google
   Roppongi 6-10-1
   Minato, Tokyo  106-6126
   JP

   Email: lorenzo@google.com

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