will map to the same solicited-node address thereby reducing the
   number of multicast addresses a node must join.

   A node is required to compute and support a Solicited-Node multicast
   addresses for every unicast and anycast address it is assigned.

   2.7 A Node's Required Addresses

   A host is required to recognize the following addresses as
   identifying itself:

      o Its Link-Local Address for each interface
      o Assigned Unicast Addresses
      o Loopback Address
      o All-Nodes Multicast Address
      o Solicited-Node Multicast Address for each of its assigned
        unicast and anycast addresses
      o Multicast Addresses of all other groups which the host belongs.

   A router is required to recognize the following addresses as
   identifying itself:

      o Its Link-Local Address for each interface
      o Assigned Unicast Addresses
      o Loopback Address
      o The Subnet-Router anycast addresses for the links it has
        interfaces.
      o All other Anycast addresses with which the router has been
        configured.
      o All-Nodes Multicast Address
      o All-Router Multicast Address
      o Solicited-Node Multicast Address for each of its assigned
        unicast and anycast addresses
      o Multicast Addresses of all other groups which the router
        belongs.

   The only address prefixes which should be predefined in an
   implementation are the:

      o Unspecified Address
      o Loopback Address
      o Multicast Prefix (FF)
      o Local-Use Prefixes (Link-Local and Site-Local)
      o Pre-Defined Multicast Addresses
      o IPv4-Compatible Prefixes

   Implementations should assume all other addresses are unicast unless
   specifically configured (e.g., anycast addresses).




 
RFC 1884              IPv6 Addressing Architecture         December 1995


REFERENCES

     [ALLOC] Rekhter, Y., and T. Li, "An Architecture for IPv6 Unicast
             Address Allocation", RFC 1887, cisco Systems, December
             1995.

     [ANYCST] Partridge, C., Mendez, T., and W. Milliken, "Host
             Anycasting Service", RFC 1546, BBN, November 1993.

     [CIDR] Fuller, V., Li, T., Varadhan, K., and J. Yu, "Supernetting:
             an Address Assignment and Aggregation Strategy", RFC 1338,
             BARRNet, cisco, Merit, OARnet, June 1992.

     [IPV6] Deering, S., and R. Hinden, Editors, "Internet Protocol,
             Version 6 (IPv6) Specification", RFC 1883, Xerox PARC,
             Ipsilon Networks, December 1995.

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

     [NSAP] Carpenter, B., Editor, "Mechanisms for OSIN SAPs, CLNP and
             TP over IPv6", Work in Progress.



SECURITY CONSIDERATIONS

   Security issues are not discussed in this document.


DOCUMENT EDITOR'S ADDRESSES

   Robert M. Hinden                     Stephen E. Deering
   Ipsilon Networks, Inc.               Xerox Palo Alto Research Center
   2191 E. Bayshore Road, Suite 100     3333 Coyote Hill Road
   Palo Alto, CA 94303                  Palo Alto, CA 94304
   USA                                  USA

   Phone: +1 415 846 4604               Phone: +1 415 812 4839
   Fax:   +1 415 855 1414               Fax:   +1 415 812 4471
   EMail: hinden@ipsilon.com            EMail: deering@parc.xerox.com