RFC 2098 (rfc2098) - Page 2 of 18

Toshiba's Router Architecture Extensions for ATM : Overview

RFC 2098          Toshiba's Router Extension for ATM       February 1997


    - It makes the best use of ATM's property while retaining current
      router-based internetworking and routing architecture.

    - It takes into account interoperability with future IP that
      supports flow concept and resource reservations.

   Section 2 of this draft explains background and motivations of our
   proposal.  Section 3 describes an overview of the proposed
   internetworking architecture and its several remarkable features.
   Section 4 discusses control architectures for CSR, which will need to
   be further investigated.

2.  Background and Motivation

   It is considered that the current hop-by-hop best effort datagram
   forwarding paradigm will not be adequate to support future large
   scale Internet which accommodates huge amount of traffic with certain
   QoS requirements.  Two major schools of investigations can be seen in
   IETF whose main purpose is to improve ability of the Internet with
   regard to its throughput and QoS.  One is to utilize ATM technology
   as much as possible, and the other is to introduce the concept of
   resource reservation and flow into IP.

1) Utilization of ATM

   Although basic properties of ATM; necessity of connection setup,
   necessity of traffic contract, etc.; is not necessarily suited to
   conventional IP datagram transmission, its excellent throughput and
   delay characteristics let us to investigate the realization of IP
   datagram transmission over ATM.

   A typical internetworking architecture is the "Classical IP Model"
   [RFC 1577].  This model allows direct ATM connectivities only between
   nodes that share the same IP address prefix.  IP datagrams should
   traverse routers whenever they go beyond IP subnet boundaries even
   though their source and destination are accommodated in the same ATM
   cloud.  Although an ATMARP is introduced which is not based on legacy
   datalink broadcast but on centralized ATMARP servers, this model does
   not require drastic changes to the legacy internetworking
   architectures with regard to the IP datagram forwarding process.
   This model still has problems of limited throughput and large
   latency, compared with the ability of ATM, due to IP header
   processing at every router.  It will become more critical when
   multimedia applications that require much larger bandwidth and lower
   latency become dominant in the near future.






Katsube, et. al.             Informational