Apparatus for fiber distributed data interface dynamic station bypass via skipping and hopping

• US 5,379,291 A
• Filed: 12/29/1992
• Issued: 01/03/1995
• Est. Priority Date: 12/29/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Herzberg, Louis P., Willebeek-LeMair, Marc H., Ruiz, Antonio
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VU, HUY DUY
• Application Number:
  US07/997,798
• Time in Patent Office: 735 Days
• Field of Search: 370/85.3, 370/85.4, 370/85.5, 370/85.12, 370/85.13, 370/85.14, 370/85.15, 370/94.3, 370/14, 370/16.1, 370/58.2, 370/75, 370/123, 370/85.1, 370/85.2 , 370/16, 370/85.6, 370/85.9
• US Class Current: 370/404
• CPC Class Codes: H04L 12/433 with asynchronous transmission, e.g. token ring, register insertion

Abstract

A rights controlling concentrator (RCC) is an apparatus for separating and controlling "rights of receiving" and "rights of transmitting" of a group of stations or groups of stations on a ring-of-trees local area network. RCC elements perform collectively to separately control, limit and/or make available the "rights of receiving" and the "rights of transmitting" of a group of stations or groups of stations. Control of the "rights of receiving" ensures that its membership is only forwarded frames transmitted by an external station which has a destination within the membership, and that the external stations only be forwarded frames transmitted by the membership which have a destination within the external stations. Frames that are transmitted to a destination in one group traverse only stations within that group. Frames that are deemed by the RCC not to be of interest to any group of stations are withheld from that group by the RCC controlling both frame receiving and transmitting rights. This significantly reduces the workload of groups of stations, because frames are not passed through station groups that are not necessary for the frames to reach their destination. Furthermore, since data frames are handled by fewer stations, the reliability of the main ring is increased. Control of the "rights of transmitting" ensures that the token is, or can be, withheld from stations that are "listen only" and need not be given the rights to transmit. This reduces the travel time of the token around the ring (and the Token Target Rotation Time (TTRT)), providing faster repeating opportunities for the transmitting stations to transmit.

Claims

1. In a local area network conforming to a ring-of-trees topology and a token-based protocol governing communication, said ring-of-trees topology having a plurality of tree nodes, each tree node comprising:

a front end and a back end, said front end having an `A` port for input and a `B` port for output, said back end having a plurality of `M` ports for attachment of standard and non-standard network elements supporting said token-based protocol governing communication;

a plurality of network elements, each `M` port being itself connected to a network element, said `M` ports within each tree node being serially connected so that all network elements in said network are serially connected to form a topological ring;

said token-based protocol governing communication between network elements through packets transmitted around said ring; and

a rights controlling concentrator within said tree node to provide minimum path routing of packets, said rights controlling concentrator including means for separating "rights of receiving" from "rights of transmitting" of network elements connected to said `M` ports and controlling these rights independently, said means being in conformance with said token-based protocol governing communication, wherein each said packet traversing said tree node is shunted by said means to bypass said front end, said back end or one or more of said `M` ports of said back end if none of the network elements avoided by said shunting are supportive of a communication objective of said packet.

2. A local area network conforming to a ring-of-trees topology and a token-based protocol, said topology having a plurality of tree nodes, each said tree node comprising:

a front end and a back end, said front end having an `A` port for input and a `B` port for output, said back end having a plurality of `M` ports for attachment of network elements supporting said token-based protocol governing communication;

a plurality of network elements, each `M` port being itself connected to a network element, said `M` ports within each said tree node being serially connected so that all network elements in said network are serially connected to form a topological ring;

said token-based protocol governing communication between said network elements through packets transmitted around said ring; and

means within said tree node for separating the "rights of receiving" from the "rights of transmitting" and controlling these rights independently, said means being in conformance with said token-based protocol governing communication, wherein each said packet traversing said tree node is shunted to bypass said front end, said back end or one or more of said `M` ports of said back end if none of the network elements avoided by said shunting are supportive of a communication objective of said packet, wherein said means further comprises

means for separating said packets into data packets and token packets for transmission on the network;

a backbone bypass controller (BBC) for shunting packets from said back end so as to bypass said front end;

a membership bypass controller (MBC) for shunting packets from said front end so as to bypass said back end;

an M-port bypass circuit (MPBC) at each of said `M` ports which, under control by said MBC, causes a packet to bypass said network elements attached to a corresponding `M` port; and

a contention arbitrator and control (CAC) element for resolving conflicts between packets, simultaneously routed to said BBC or said MBC, and avoiding loss of packets.

3. A method of providing minimum path routing of packets on a token ring network of trees, said network having a plurality of trees and standard and non-standard stations supporting a token-based protocol governing communication with each of a number of stations being connected to said token ring network of trees through one of said trees, said method comprising:

separating packets into data packets and token packets for transmission on the network;

affording rights of transmitting to said stations;

routing said token packets through each station of said network that is afforded rights of transmitting;

giving receiving rights to a tree of said network;

routing said data packets through all stations of a tree of said network only if said tree is given receiving rights for said data packet by nature of its being addressed to one of said all stations of said tree; and

controlling separately the rights of transmitting and rights of receiving of the stations of said tree via hopping.

4. A method of providing minimum path routing of packets on a token ring network of trees, said network having a plurality of trees and stations supporting a token-based protocol governing communication with each of a number of said stations being connected to said network through one of said trees, said method comprising the steps of:

separating said packets into data packets and token packets for transmission on the network;

affording stations of said network rights of transmitting;

routing said token packets through each station of said network that is afforded rights of transmitting;

giving a tree of said network receiving rights, receiving rights for a tree otherwise being withheld;

routing said data packets through all stations of a tree of said network only if said tree is given receiving rights for said data packet by nature of its being addressed to one of said all stations of said tree;

routing a data packet to bypass all stations of said tree, when receiving rights are withheld, if said data packet is addressed to any of said all stations of said tree;

controlling separately the rights of transmitting and rights of receiving of the stations of said tree via skipping and hopping of packets; and

arbitrating contention between packets on said ring according to a priority scheme, said priority scheme providing delay-free performance of the token ring network when skipping and hopping said packets.