One document matched: draft-ietf-ipngwg-ipv6router-alert-01.txt

Differences from draft-ietf-ipngwg-ipv6router-alert-00.txt

INTERNET-DRAFT                              Dave Katz, Juniper Networks
                                               Randall Atkinson, @ Home
                                                          21 April 1997


                        IPv6 Router Alert Option

              <draft-ietf-ipngwg-ipv6router-alert-01.txt>



Status of this Memo

   This document is an Internet Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its Areas,
   and its Working Groups.  Note that other groups may also distribute
   working documents as Internet Drafts.

   Internet Drafts are draft documents valid for a maximum of six
   months.  Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a "working
   draft" or "work in progress."

   Please check the I-D abstract listing contained in each Internet
   Draft directory to learn the current status of this or any Internet
   Draft.

   This draft expires October 21, 1997.

Abstract

   This memo describes a new IPv6 Hop-by-Hop Option type that alerts
   transit routers to more closely examine the contents of an IP packet.
   This is useful for protocols addressed to a destination but also
   require special processing in routers along the path.


1.0  Introduction

   IPv6 uses daisy-chained optional headers to increase flexibility and
   remove the IPv4 constraint on how large options can be.  Because what
   kind of upper layer information is present in a given IPv6 packet.
   Some control packets that are interesting to routers (e.g.  RSVP
   messages) are addressed to the same destination as data packets
   belonging to that session.  It is desirable to forward the data-only
   packets as rapidly as possible, while ensuring that the router
   processes control packets appropriately.  At present, the router



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   cannot easily fast switch packets containing optional headers because
   it needs to determine whether or not the upper layer information is
   control information needed by the router.  As noted before, the
   parsing to determine this causes the packet to traverse the slow path
   through the router.  This situation is undesirable.

   This draft defines the a new mandatory option within the IPv6 Hop-by-
   Hop Header.  The presence of this option in an IPv6 packet informs
   the router to slow-path process this router and handle any control
   data accordingly.  The absence of this option in an IPv6 packet
   informs the router that the packet does not contain information
   needed by the router and hence can safely be fast switched without
   further packet parsing.  Hosts originating IPv6 packets are required
   to include this option in certain circumstances.


2.0  Approach

   The goal is to provide a mechanism whereby routers can intercept
   packets not addressed to them directly without incurring any
   significant performance penalty.  The described solution is to define
   a new IPv6 Hop-by-Hop Header option having the semantic "routers
   should examine this packet more closely" and require protocols such
   as RSVP to use this option.  This would incur little performance
   penalty on the forwarding of normal data packets.

   Routers that support option processing in the fast path already
   demultiplex processing based on the Hop-by-Hop header options.  If
   all hop-by-hop option types are supported in the fast path, then the
   addition of another option type to process is unlikely to impact
   performance.  If some hop-by-hop option types are not supported in
   the fast path, this new option type will be unrecognized and cause
   packets carrying it to be kicked out into the slow path, so no change
   to the fast path is necessary, and no performance penalty will be
   incurred for regular data packets.

   Routers that do not support option processing in the fast path will
   cause packets carrying this new option to be forwarded through the
   slow path, so no change to the fast path is necessary and no
   performance penalty will be incurred for regular data packets.











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2.1  Syntax

   The router alert option has the following format:

                 +--------+--------+--------+--------+
                 |IANA=TBD| Len= 2 | Value (2 octets)|
                 +--------+--------+--------+--------+

      "IANA-TBD" is the Hop-by-Hop Option Type number (To be allocated
      by IANA).

      Nodes not recognizing this option should skip over this option and
      continue processing the header.  This option MUST NOT change en
      route.

      Value:  A 2 octet code with the following values:

         0        Packet contains ICMPv6 Group Membership message.
         1        Packet contains RSVP message.
         2-65535  Reserved to IANA for future use.


2.2  Semantics

   Hosts shall ignore this option upon receipt.  Routers that do not
   recognize this option shall ignore it.  Routers that recognize this
   option shall examine packets carrying it more closely (parse the
   entire packet checking for interesting values of NextHeader fields,
   for example) to determine whether or not further processing is
   necessary.  The value field may be used by an implementation to speed
   processing of the packet within the transit router.  Unrecognized
   value fields shall be silently ignored.

   All other values of the VALUE field are reserved to IANA for future
   use.


3.0  Impact on Other Protocols

   For this option to be effective, its use must be mandated in
   protocols that expect routers to perform significant processing on
   packets not directly addressed to them.

   All IPv6 packets containing an ICMPv6 Group Membership message MUST
   contain this option within the IPv6 Hop-by-Hop Options Header of such
   packets.

   All IPv6 packets containing an RSVP message MUST contain this option



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   within the IPv6 Hop-by-Hop Options Header of such packets.


4.0 Security Considerations

   Security issues are not discussed in this document.


5.0  References

    [DH95]    Deering, S. & R. Hinden, "IPv6 Specification", RFC-1883,
              Internet Engineering Task Force, December 1995.

    [BZEHJ95] Braden, B. (ed.), L. Zhang, D. Estrin, S. Herzog, S.
              Jamin, "Resource ReSerVation Protocol (RSVP)," Internet
              Draft, 1996.


Authors' Addresses

   Dave Katz
   Juniper Networks
   3260 Jay Street
   Santa Clara, CA 95054
   USA

   Phone:  +1 (408) 327-0173
   Email:  dkatz@jnx.com


   Randall Atkinson
   @ Home Network
   385 Ravendale Drive
   Mountain View, CA 94043

   Phone:  +1 (415) 944-7200
   Email:  rja@inet.org














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