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Browse Prior Art Database

Binary-Tree Multicast

IP.com Disclosure Number: IPCOM000112879D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Engbersen, AP: AUTHOR [+2]

Abstract

Typical switching elements for packet switching networks, like shared-buffer ATM-like (Asynchronous Transfer Mode) switches, have been proposed with efficient Multicast/Broadcast mechanisms [*]. A limitation, however, with any VLSI implementation of such a switching element is formed by the available chip real-estate. This leads to the fact that the number of simultaneous multicast connections through such an element will be limited to a subset of the total possible. Note that for a 16-output switching element, there are 65 536 possible different multicast connections. It is not possible to provide the means on-chip to support that many concurrent multicast trees defined concurrently.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Binary-Tree Multicast

      Typical switching elements for packet switching networks, like
shared-buffer ATM-like (Asynchronous Transfer Mode) switches, have
been proposed with efficient Multicast/Broadcast mechanisms [*].  A
limitation, however, with any VLSI implementation of such a switching
element is formed by the available chip real-estate.  This leads to
the fact that the number of simultaneous multicast connections
through such an element will be limited to a subset of the total
possible.  Note that for a 16-output switching element, there are 65
536 possible different multicast connections.  It is not possible to
provide the means on-chip to support that many concurrent multicast
trees defined concurrently.

      In a switch operating in a typical multicast environment, the
aggregate output data stream is much higher than the input data
stream.  Consequently, one can expect that in such cases the inputs
to the switch are not heavy loaded.  This leads to the proposal to
achieve a large number of multicast trees by implementing a
binary-tree branch at each passage through the switch element.  If,
i.e., from input 5 a multicast connection to the outputs 3,7,9,13 and
15 is wished, five passes through the switch element are made (option
1):

1.  multicast from input 5 to output 5 and output 3

2.  multicast from input 5 to output 5 and output 7

3.  multicast from input 5 to output 5 and output 9

4.  multicast from input 5 to output 5 and output 13

5.  non-multicast from input 5 to output 15

      This requires only that the cell can be fed back from output 5
to input 5.  Because in most cases a single adapter card will carry
the logic for input and output, this is easy.  ...