US 5,351,043 A · Queueing protocol

Abstract

A method of transmitting data on a communications network having two oppositely directed unidirectional buses (A,B) and a number of access units (4) coupled between buses, the method including the step of establishing a queue which is distributed in the access units and which controls when the access units can transmit data packets on the buses. When an access unit has a data packet (38) queued for transmission on bus A, it sends a REQ bit on bus B. The access units monitor the number of REQ bits passing and empty packets available so as to thereby establish the distributed queue. The access units are able to handle both data packets (38) which are suitable for information from computers and synchronous packets 36 which can be used for voice circuits.

Claims45

Dependent claims

A method of queuing data packets for transmission from access units in a network having first and second oppositely directed buses with a plurality of access units coupled between the buses, said method including the steps, when an access unit has a data packet for transmission, of:

(a) determining on which one of the buses the data packet is to be transmitted,
(b) transmitting a request flag on the other of the buses, and
(c) selecting an empty or available data packet on said one bus for transmission of the data packet from the access unit with reference to the number of empty or available packets received at the access unit on said one bus and the number of request flags received at the access unit on said other bus.

A communications network for queued transmission of information in data packets, said network comprising:

first and second oppositely directed unidirectional buses;
and
a plurality of access units coupled between the buses, said access units producing request flags on the buses when they have data packets for transmission thereon, said access units including:
(a) means for determining on which one of the buses the data packet is to be transmitted,
(b) request flag generating means for transmitting a request flag on the other of the buses, and
(c) logic means for selecting an empty or available data packet on said one bus for transmission of the data packet from the access unit with reference to the number of empty or packets available packets received at the access unit on said one bus and the number of request flags received at the access unit on said other bus.

3 more elements

An access unit for transmission of information in packets, in a network which includes first and second oppositely directed unidirectional buses, said access unit including:

(a) determining means for determining on which one of the buses a data packet is to be transmitted;
(b) request flag generating means for generating a request flag for transmission on the second bus when the access unit has a data packet for transmission on the first bus;
and
(c) logic means for selecting an empty or available data packet on said one bus for transmission of the data packet from the access unit with reference to the number of empty or available packets received at the access unit on said one bus and the number of request flags received at the access unit on said other bus.

1 more element

Dependencies are inferred from the claim text.

Queueing protocol

Life of this patent

Queueing protocol

Life of this patent

Abstract

Claims45