rfc1885.txt

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   Destination Address

                  Any legal IPv6 address.

   ICMPv6 Fields:

   Type           128

   Code           0

   Identifier     An identifier to aid in matching Echo Replies
                  to this Echo Request.  May be zero.

   Sequence Number

                  A sequence number to aid in matching Echo Replies
                  to this Echo Request.  May be zero.

   Data           Zero or more octets of arbitrary data.

   Description

   Every node MUST implement an ICMPv6 Echo responder function that
   receives Echo Requests and sends corresponding Echo Replies.  A node
   SHOULD also implement an application-layer interface for sending Echo
   Requests and receiving Echo Replies, for diagnostic purposes.

   Upper layer notification

   A node receiving this ICMPv6 message MAY notify the upper-layer
   protocol.




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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


4.2 Echo Reply Message

       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             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Identifier          |        Sequence Number        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Data ...
      +-+-+-+-+-

   IPv6 Fields:

   Destination Address

                  Copied from the Source Address field of the invoking
                  Echo Request packet.

   ICMPv6 Fields:

   Type           129

   Code           0

   Identifier     The identifier from the invoking Echo Request message.

   Sequence       The sequence number from the invoking Echo Request
   Number         message.

   Data           The data from the invoking Echo Request message.

   Description

   Every node MUST implement an ICMPv6 Echo responder function that
   receives Echo Requests and sends corresponding Echo Replies.  A node
   SHOULD also implement an application-layer interface for sending Echo
   Requests and receiving Echo Replies, for diagnostic purposes.

   The source address of an Echo Reply sent in response to a unicast
   Echo Request message MUST be the same as the destination address of
   that Echo Request message.

   An Echo Reply SHOULD be sent in response to an Echo Request message
   sent to an IPv6 multicast address.  The source address of the reply
   MUST be a unicast address belonging to the interface on which the
   multicast Echo Request message was received.




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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


   The data received in the ICMPv6 Echo Request message MUST be returned
   entirely and unmodified in the ICMPv6 Echo Reply message, unless the
   Echo Reply would exceed the MTU of the path back to the Echo
   requester, in which case the data is truncated to fit that path MTU.

   Upper layer notification

   Echo Reply messages MUST be passed to the ICMPv6 user interface,
   unless the corresponding Echo Request originated in the IP layer.










































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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


4.3 Group Membership Messages

   The ICMPv6 Group Membership Messages have the following format:

       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             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Maximum Response Delay    |          Unused               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                          Multicast                            |
      +                                                               +
      |                           Address                             |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv6 Fields:

   Destination Address

                  In a Group Membership Query message, the multicast
                  address of the group being queried, or the Link-Local
                  All-Nodes multicast address.

                  In a Group Membership Report or a Group Membership
                  Reduction message, the multicast address of the
                  group being reported or terminated.

   Hop Limit      1

   ICMPv6 Fields:

   Type           130 - Group Membership Query
                  131 - Group Membership Report
                  132 - Group Membership Reduction

   Code           0

   Maximum Response Delay

                  In Query messages, the maximum time that responding
                  Report messages may be delayed, in milliseconds.





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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


                  In Report and Reduction messages, this field is
                  is initialized to zero by the sender and ignored by
                  receivers.

   Unused         Initialized to zero by the sender; ignored by receivers.

   Multicast Address

                  The address of the multicast group about which the
                  message is being sent.  In Query messages, the Multicast
                  Address field may be zero, implying a query for all
                  groups.

   Description

   The ICMPv6 Group Membership messages are used to convey information
   about multicast group membership from nodes to their neighboring
   routers.  The details of their usage is given in [RFC-1112].

































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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


5. References

   [IPv6]       Deering, S., and R. Hinden, "Internet Protocol, Version
                6, Specification", RFC 1883, Xerox PARC, Ipsilon
                Networks, December 1995.

   [IPv6-ADDR]  Hinden, R., and S. Deering, Editors, "IP Version 6
                Addressing Architecture", RFC 1884, Ipsilon Networks,
                Xerox PARC, December 1995.

   [IPv6-DISC]  Narten, T., Nordmark, E., and W. Simpson, "Neighbor
                Discovery for IP Version 6 (IPv6)", Work in Progress.

   [RFC-792]    Postel, J., "Internet Control Message Protocol", STD 5,
                RFC 792, USC/Information Sciences Institute, September
                1981.

   [RFC-1112]   Deering, S., "Host Extensions for IP Multicasting", STD
                5, RFC 1112, Stanford University, August 1989.

   [RFC-1122]   Braden, R., "Requirements for Internet Hosts -
                Communication Layers", STD 3, RFC 1122, USC/Information
                Sciences Institute, October 1989.

   [RFC-1191]   Mogul, J., and S. Deering, "Path MTU Discovery", RFC
                1191, DECWRL, Stanford University, November 1990.


6. Acknowledgements

   The document is derived from previous ICMP drafts of the SIPP and
   IPng working group.

   The IPng working group and particularly Robert Elz, Jim Bound, Bill
   Simpson, Thomas Narten, Charlie Lynn, Bill Fink, and Scott Bradner
   (in chronological order) provided extensive review information and
   feedback.


7. Security Considerations

   Security issues are not discussed in this memo.









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RFC 1885                 ICMPv6 (ICMP for IPv6)            December 1995


Authors' Addresses:

   Alex Conta                            Stephen Deering
   Digital Equipment Corporation         Xerox Palo Alto Research Center
   110 Spitbrook Rd                      3333 Coyote Hill Road
   Nashua, NH 03062                      Palo Alto, CA 94304

   Phone: [phone]                Phone: [phone]
   EMail: [e-mail]              EMail: [e-mail]










































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