Modification to Default Value of SOL_MAX_RT

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Document Type Active Internet-Draft (dhc WG)
Last updated 2013-06-03
Replaces draft-droms-dhc-dhcpv6-solmaxrt-update
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Network Working Group                                           R. Droms
Internet-Draft                                             Cisco Systems
Updates: 3315 (if approved)                                June 03, 2013
Intended status: Standards Track
Expires: December 05, 2013

              Modification to Default Value of SOL_MAX_RT


   This document updates RFC 3315 by redefining the default values for
   SOL_MAX_RT and INF_MAX_RT, and defining options through which a
   DHCPv6 server can override the client's default value for SOL_MAX_RT
   and INF_MAX_RT with a new value.

Status of This Memo

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Droms                  Expires December 05, 2013                [Page 1]
Internet-Draft          DHCPv6 SOL_MAX_RT Option               June 2013

1.  Introduction

   Section 5.5 of the DHCPv6 specification [RFC3315] defines the default
   values of SOL_MAX_RT and INF_MAX_RT to be 120 seconds.  In some
   circumstances, these defaults will lead to an unacceptably high
   volume of aggregated traffic at a DHCPv6 server.

   The change to SOL_MAX_RT is in response to DHCPv6 message rates
   observed at a DHCPv6 server in a deployment in which many DHCPv6
   clients are sending Solicit messages but the DHCPv6 server has been
   configured not to respond to those Solicit messages.  While no
   explicit observations of traffic due to INF_MAX_RT have been
   conducted, this document updates INF_MAX_RT for consistency with

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

3.  Updates to SOL_MAX_RT and INF_MAX_RT in RFC 3315

   This document changes section 5.5 of RFC 3315 [RFC3315] as follows:

      SOL_MAX_RT      120 secs  Max Solicit timeout value

      SOL_MAX_RT     3600 secs  Max Solicit timeout value

      INF_MAX_RT      120 secs  Max Information-request timeout value

      SOL_MAX_RT     3600 secs  Max Information-request timeout value

   With this change, a DHCPv6 client that does not receive a
   satisfactory response will send Solicit or Information-request
   messages with the same initial frequency and exponential backoff as
   specified in sections 17.1.2 and 18.1.5 of RFC 3315 [RFC3315].
   However, the long term behavior of these DHCPv6 clients will be to
   send a Solicit or Information-request message every 3600 seconds
   rather than every 120 seconds, significantly reducing the aggregated
   traffic at the DHCPv6 server.

Droms                  Expires December 05, 2013                [Page 2]
Internet-Draft          DHCPv6 SOL_MAX_RT Option               June 2013

4.  SOL_MAX_RT option

   A DHCPv6 server sends the SOL_MAX_RT option to a client to override
   the default value of SOL_MAX_RT.  The value of SOL_MAX_RT in the
   option replaces the default value defined in Section 3.  One use for
   the SOL_MAX_RT option is to set a longer value for SOL_MAX_RT, which
   reduces the Solicit traffic from a client that has not received a
   response to its Solicit messages.

   The format of the SOL_MAX_RT option is:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       |          option-code          |         option-len            |
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