RFC 1932 (rfc1932) - Page 2 of 31

IP over ATM: A Framework Document

RFC 1932           IP over ATM: A Framework Document          April 1996


   o Section 5 discusses tradeoffs between connection oriented and
     connectionless approaches.

   o Section 6 discusses the various means of providing direct
     connections across IP subnet boundaries.

   o Section 7 discusses the proposal to extend IP routing to better
     accommodate direct connections across IP subnet boundaries.

   o Section 8 identifies several prominent IP over ATM proposals that
     have been discussed within the IP over ATM Working Group and
     their relationship to the framework described in this document.

   o Section 9 addresses the relationship between the documents
     developed in the IP over ATM and related working groups and the
     various models discussed.

2.  Definitions and Terminology

   We define several terms:

   A Host or End System: A host delivers/receives IP packets to/from
     other systems, but does not relay IP packets.

   A Router or Intermediate System: A router delivers/receives IP
     packets to/from other systems, and relays IP packets among
     systems.

   IP Subnet: In an IP subnet, all members of the subnet are able to
      transmit packets to all other members of the subnet directly,
      without forwarding by intermediate entities.  No two subnet
      members are considered closer in the IP topology than any other.
      From an IP routing and IP forwarding standpoint a subnet is
      atomic, though there may be repeaters, hubs, bridges, or switches
      between the physical interfaces of subnet members.

   Bridged IP Subnet: A bridged IP subnet is one in which two or
      more physically disjoint media are made to appear as a single IP
      subnet.  There are two basic types of bridging, media access
      control (MAC) level, and proxy ARP (see section 6).

   A Broadcast Subnet: A broadcast network supports an arbitrary
      number of hosts and routers and additionally is capable of
      transmitting a single IP packet to all of these systems.

   A Multicast Capable Subnet: A multicast capable subnet supports
     a facility to send a packet which reaches a subset of the
     destinations on the subnet.  Multicast setup may be sender



Cole, Shur & Villamizar      Informational