Browse Prior Art Database

Medium Access Protocol for Connection Oriented Packet Switched Multi-channel Broadcast Networks

IP.com Disclosure Number: IPCOM000110602D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 136K

Publishing Venue

IBM

Related People

Kravitz, JK: AUTHOR [+3]

Abstract

The invention proposes a medium-access (MAC) protocol for broadcast packet-switched multichannel networks that efficiently supports connection-oriented traffic with minimal hardware requirements.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Medium Access Protocol for Connection Oriented Packet Switched Multi-channel Broadcast Networks

       The invention proposes a medium-access (MAC) protocol for
broadcast packet-switched multichannel networks that efficiently
supports connection-oriented traffic  with minimal hardware
requirements.

      High-speed networks, such as those using wavelength division
multiplexing, use many channels, with each channel used to send data
at rates up to 1 Gb/s, to realize enormous capacities.  This capacity
has to be shared among the network nodes in some coordinated manner.
This requires an efficient MAC protocol.

      In such networks, we expect traffic to be predominantly
connection-oriented.  At any given time, each node usually has
logical connections with several (but not all) other nodes in the
network.  Prior art (see [1] for a complete list), for the most part,
deals with datagram-type traffic as opposed to connection-oriented
traffic.  Recently, two protocols [1,2] have been proposed to support
connection-oriented traffic efficiently.  Each node is required to be
equipped with at least a rapidly-tunable transmitter and
rapidly-tunable receiver in [1] while [2] requires each node to be
equipped with a tunable transmitter and fixed-tuned receiver.
However, rapidly tunable transmitters are not available today, but
rapidly tunable receivers using acousto-optic filters (see the
preceding article) may soon be available.  Thus, here we propose a
protocol that requires only fixed-tuned transmitters and tunable
receivers.

      We assume that each node i is equipped with two fixed-tuned
transmitters (FTs), one at a unique wavelength gi used for data and
another at a common shared wavelength gc used for control, as in [3].
Each node is also equipped with a tunable receiver (TR) for receiving
data, as well as another receiver fixed-tuned to gc (FR) for
receiving control information.  We show later that the protocol can
be implemented with a single FT, TR and  FR at each node.

      All nodes in the network are assumed to be synchronized to a
common global clock.  Time is divided into frames.  On the data
channels, a frame is divided into n slots.  The number n denotes the
maximum number of connections that can be set up with a given node at
any given time.  On the control channel a frame is divided into m
slots, where m is an arbitrary number.

      Suppose a node X wants to establish a simplex connection with a
node Y.  X transmits a connection request packet on gc on one of the
m slots.  The packet contains the source address (X), destination
address (Y), a list of available data slots on X's FT at gX (for
example, slots 1, 2, 4), and the number of slots (out of n ) desired
for the connection (say, 1 slot).  This packet may collide with other
packets transmitted on the control channel.  But since connection
set-ups are expected to occur infrequently, the probability of
collision is small.  If a coll...