rfc2461.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

                     It MUST NOT be a multicast address.

   Possible options:

      Source link-layer address
                     The link-layer address for the sender.  MUST NOT be
                     included when the source IP address is the
                     unspecified address.  Otherwise, on link layers
                     that have addresses this option MUST be included in
                     multicast solicitations and SHOULD be included in
                     unicast solicitations.

      Future versions of this protocol may define new option types.
      Receivers MUST silently ignore any options they do not recognize
      and continue processing the message.






















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RFC 2461              Neighbor Discovery for IPv6          December 1998


4.4.  Neighbor Advertisement Message Format

   A node sends Neighbor Advertisements in response to Neighbor
   Solicitations and sends unsolicited Neighbor Advertisements in order
   to (unreliably) propagate new information quickly.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Code      |          Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|S|O|                     Reserved                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                       Target Address                          +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Options ...
      +-+-+-+-+-+-+-+-+-+-+-+-

   IP Fields:

      Source Address
                     An address assigned to the interface from which the
                     advertisement is sent.

      Destination Address
                     For solicited advertisements, the Source Address of
                     an invoking Neighbor Solicitation or, if the
                     solicitation's Source Address is the unspecified
                     address, the all-nodes multicast address.

                     For unsolicited advertisements typically the all-
                     nodes multicast address.

      Hop Limit      255

   Authentication Header
                     If a Security Association for the IP Authentication
                     Header exists between the sender and the
                     destination address, then the sender SHOULD include
                     this header.





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RFC 2461              Neighbor Discovery for IPv6          December 1998


   ICMP Fields:

      Type           136

      Code           0

      Checksum       The ICMP checksum.  See [ICMPv6].

      R              Router flag.  When set, the R-bit indicates that
                     the sender is a router.  The R-bit is used by
                     Neighbor Unreachability Detection to detect a
                     router that changes to a host.

      S              Solicited flag.  When set, the S-bit indicates that
                     the advertisement was sent in response to a
                     Neighbor Solicitation from the Destination address.
                     The S-bit is used as a reachability confirmation
                     for Neighbor Unreachability Detection.  It MUST NOT
                     be set in multicast advertisements or in
                     unsolicited unicast advertisements.

      O              Override flag.  When set, the O-bit indicates that
                     the advertisement should override an existing cache
                     entry and update the cached link-layer address.
                     When it is not set the advertisement will not
                     update a cached link-layer address though it will
                     update an existing Neighbor Cache entry for which
                     no link-layer address is known.  It SHOULD NOT be
                     set in solicited advertisements for anycast
                     addresses and in solicited proxy advertisements.
                     It SHOULD be set in other solicited advertisements
                     and in unsolicited advertisements.

      Reserved       29-bit unused field.  It MUST be initialized to
                     zero by the sender and MUST be ignored by the
                     receiver.

      Target Address
                     For solicited advertisements, the Target Address
                     field in the Neighbor Solicitation message that
                     prompted this advertisement.  For an unsolicited
                     advertisement, the address whose link-layer address
                     has changed.  The Target Address MUST NOT be a
                     multicast address.







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RFC 2461              Neighbor Discovery for IPv6          December 1998


   Possible options:

      Target link-layer address
                     The link-layer address for the target, i.e., the
                     sender of the advertisement.  This option MUST be
                     included on link layers that have addresses when
                     responding to multicast solicitations.  When
                     responding to a unicast Neighbor Solicitation this
                     option SHOULD be included.

                     The option MUST be included for multicast
                     solicitations in order to avoid infinite Neighbor
                     Solicitation "recursion" when the peer node does
                     not have a cache entry to return a Neighbor
                     Advertisements message.  When responding to unicast
                     solicitations, the option can be omitted since the
                     sender of the solicitation has the correct link-
                     layer address; otherwise it would not have be able
                     to send the unicast solicitation in the first
                     place. However, including the link-layer address in
                     this case adds little overhead and eliminates a
                     potential race condition where the sender deletes
                     the cached link-layer address prior to receiving a
                     response to a previous solicitation.

      Future versions of this protocol may define new option types.
      Receivers MUST silently ignore any options they do not recognize
      and continue processing the message.























Narten, et. al.             Standards Track                    [Page 25]

RFC 2461              Neighbor Discovery for IPv6          December 1998


4.5.  Redirect Message Format

   Routers send Redirect packets to inform a host of a better first-hop
   node on the path to a destination.  Hosts can be redirected to a
   better first-hop router but can also be informed by a redirect that
   the destination is in fact a neighbor.  The latter is accomplished by
   setting the ICMP Target Address equal to the ICMP Destination
   Address.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Code      |          Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Reserved                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                       Target Address                          +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                     Destination Address                       +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Options ...
      +-+-+-+-+-+-+-+-+-+-+-+-

   IP Fields:

      Source Address
                     MUST be the link-local address assigned to the
                     interface from which this message is sent.

      Destination Address
                     The Source Address of the packet that triggered the
                     redirect.

      Hop Limit      255





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RFC 2461              Neighbor Discovery for IPv6          December 1998


      Authentication Header
                     If a Security Association for the IP Authentication
                     Header exists between the sender and the
                     destination address, then the sender SHOULD include
                     this header.

   ICMP Fields:

      Type           137

      Code           0

      Checksum       The ICMP checksum.  See [ICMPv6].

      Reserved       This field is unused.  It MUST be initialized to
                     zero by the sender and MUST be ignored by the
                     receiver.

      Target Address An IP address that is a better first hop to use for
                     the ICMP Destination Address.  When the target is
                     the actual endpoint of communication, i.e., the
                     destination is a neighbor, the Target Address field
                     MUST contain the same value as the ICMP Destination
                     Address field.  Otherwise the target is a better
                     first-hop router and the Target Address MUST be the
                     router's link-local address so that hosts can
                     uniquely identify routers.

      Destination Address
                     The IP address of the destination which i