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Multicast Mechanism for Switched Multimegabit Data Service Intra Node Multicast Mechanism

IP.com Disclosure Number: IPCOM000118551D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 117K

Publishing Venue

IBM

Related People

Druon, S: AUTHOR [+5]

Abstract

Disclosed is a set of mechanisms that can be used to provide an efficient service for multicasting a message from a node in the network to multiple destinations. One example of a protocol that may use such a set of mechanisms is a connection-less service like the Bellcore defined Switched Multimegabit Data Service (SMDS) or the European equivalent, the Connection-less BroadBand Data Service (CBDS). The connection-less service is provided in this case as an overlay service over an Asynchronous Transfer Mode (ATM) network. These mechanisms are used in the case of a connection-less server (CLS) node containing multiple server cards (providing the ingress and/or egress connection-less functions) and multiple input-output adapter cards providing access to the underlying ATM network.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 46% of the total text.

Multicast Mechanism for Switched Multimegabit Data Service Intra
Node Multicast Mechanism

      Disclosed is a set of mechanisms that can be used to provide an
efficient service for multicasting a message from a node in the
network to multiple destinations.  One example of a protocol that may
use such a  set of mechanisms is a connection-less service like the
Bellcore defined  Switched Multimegabit Data Service (SMDS) or the
European equivalent, the Connection-less BroadBand Data Service
(CBDS).  The connection-less  service is provided in this case as an
overlay service over an Asynchronous Transfer Mode (ATM) network.
These mechanisms are used in  the case of a connection-less server
(CLS) node containing multiple server cards (providing the ingress
and/or egress connection-less functions) and multiple input-output
adapter cards providing access to  the underlying ATM network.  All
of these cards are interconnected via  a common switching fabric.
The underlying ATM network is used to interconnect servers with each
other when multiple servers are present  and is also used to connect
subscribers to their respective server. A  major service provided by
these connection-less protocols is group addressing.  When a datagram
is group addressed, the datagram must be transmitted to all the
destinations and subscribers that the network has  been instructed to
consider as members of the group.

      In a SMDS server node made up by multiple server cards
providing SMDS functionality and of multiple input-output adapters
providing ATM network attachment capabilities, the handling of the
egress function for a group addressed datagram is a key design item.
The egress SMDS server card has to exploit the destination E.164
group address in the SMDS Protocol Data Unit to determine onto which
subscriber interfaces the datagram must be delivered to.  Each
input-output adapter  potentially handles multiple ATM Virtual
Channel Connections (VCCs) to  the SMDS subscribers and several
input-output adapters may coexist in the node.  The strategy adopted
to make copies of the datagram available  to every required
subscriber access has an enormous impact on the system  performance.
  o  An obvious solution would consist in the egress SMDS server
      card sending a copy of the datagram for each VCC the datagram
      must be delivered on.  Obviously, this immediately would have
      the effect of creating an unacceptable bottleneck at the
      switching medium level.
  o  Another possibility would be to use the multicast (if any)
      capability of the switching fabric to reach all the
      subscribers accesses involved by the group address.
      Unfortunately, the number of combinations cannot easily be
      achieved by any known switching fabric.
  o  Another solution may consist in placing the SMDS egress
      functionality in every input-output adapter card and having
     ...