Multiport LAN bridge

• US 5,448,565 A
• Filed: 11/12/1992
• Issued: 09/05/1995
• Est. Priority Date: 11/12/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sanaye, Simin H., Ku, Edward H. C., Coates, Joseph W., Chang, Paul
• Primary Examiner(s): Kizou, Hassan
• Application Number:
  US07/975,236
• Time in Patent Office: 1,027 Days
• Field of Search: 370/85.1, 370/85.2, 370/85.9, 370/85.11, 370/85.13, 370/85.14, 370/92, 370/94.1, 370/94.3, 340/825.52
• US Class Current: 370/402
• CPC Class Codes: H04L 12/46 Interconnection of networks

Abstract

A multiport bridge includes a plurality of Bridge Port Frame Handler (BPFH) units coupled through a Source Routing bus and a Transparent Bridge Bus to a microcontroller, a Packet Memory and a Transparent Bridge Control Management System (TBCMS). Each Bridge Port Frame Handler unit receives Frames from its attached LAN, forwards selected portions of Source Routing Frames to other Bridge Port Frame Handler Units for further processing. Likewise, selected portions of Transparent Bridge Frames are forwarded to the TBCMS whereat routing information and signature information is extracted and returned to the forwarding BPFH unit for further processing.

Claims

1. An apparatus for interconnecting communications networks comprising:

a first bus means for transporting information;

a second bus means for transporting information;

at least one bridge port frame handler means coupled to the first bus means and the second bus means;

said at least one bridge port frame handler means receiving frames from or transmitting frames onto at least one of the communications networks;

a first means for storing data provided by the at least one bridgeport frame handler means coupled to the first bus means;

a first bus arbiter coupled to the first bus means, said first bus arbiter being responsive to requests to grant access to said first bus means;

a transparent bridge routing (TBR) means for processing transparent bridge frames coupled to the second bus means; and

a first controller means, coupled to the transparent bridge routing means and the first bus means, said first controller means controlling the transparent bridge routing means and selected ones of components directly connected to the first bus means.

2. The apparatus of claim 1 further including at least one LAN controller interconnecting the at least one bridge port frame handler to at least one communications network.

3. The apparatus of claim 1 further including a first circuit means disposed between the controller means and the transparent bridge routing means;

said first circuit means being responsive to control signals provided by said first controller means to electrically isolate said controller means from the transparent bridge routing means.

4. The apparatus of claim 3 further including a second circuit means connecting the at least one bridge port handler means to the second bus means;

said second circuit means being responsive to control signals provided by said transparent bridge routing means to electrically isolate said at least one bridge port handler from the second bus means.

5. The apparatus of claim 1 wherein the transparent bridge routing means includes a first buffer means for storing destination address/source address;

a second bus arbiter for allowing said at least one port handler means to access the second bus means;

a central data bank means for storing station addresses and associated signature information including bridge port handler addresses, communication network types, network protocol information and control information; and

a second control means responsive to data in the first buffer and control signals generated by the second bus arbiter to correlate the addresses in the central data bank means with an address in the first buffer and upon a matched address, extracting from said central data bank means signature information associated with the matched address and for writing said signature information to the at least one bridge port handler means.

6. The apparatus of claim 5 further including an auxiliary data bank means coupled to the second control means and the first buffer means;

said auxiliary data bank means responsive to control signals generated by the second control means to move an address from the first buffer means into the auxiliary data bank means when the address in said first buffer means does not match an entry in the central data bank means.

7. The apparatus of claim 6 further including an aging facility means interconnecting the first controller means and the central data bank means, said aging facility means responsive to control signals outputted from the first control means to update and/or delete selected information from the central data bank means.

8. The apparatus of claim 6 wherein the auxiliary data bank means include a second SRAM for storing station addresses not found in the central data bank means;

and

a third controller coupled to the second SRAM.

9. The apparatus of claim 5 further including an update buffer means for storing information to update the central bank means coupled to the first control means and the second control means;

said second control means responsive to control signals outputted from the first control means to transfer the information from the update buffer means to the central data bank means.

10. The apparatus of claim 5 wherein the central data bank means include a CAM for storing station addresses;

and

a first SRAM for storing signature information on LAN stations.

11. The apparatus of claim 1 further including at least one adapter coupling the at least one bridge port handler means to at least one communications network.

12. The apparatus of claim 11 wherein the transparent bridge routing means includes a first buffer means for storing destination address/source address data;

a second bus arbiter for allowing said at least one port handler means to access the second bus means;

a central data bank means for storing information including station addresses, bridge port handler addresses, communications network types, network protocol information and control information;

a second control means responsive to data in the first buffer means and control signals generated by the second bus arbiter to correlate the addresses in the central data bank means with an address in the first buffer means and upon a matched address, extracting from said central data bank means signature information associated with the matched address and for writing said signature information to the at least one bridge port handler means.

13. The apparatus of claim 11 wherein the at least one adapter includes a Token Ring adapter, an ethernet adapter or FDDI adapter.

14. The apparatus of claim 11 wherein the at least one bridge port frame handler means includes a Bridged frame process unit for interfacing with the second bus means;

a hardware device driver for interfacing with a LAN;

a system interface unit for interfacing with the first bus means;

a Receive frame buffer coupled to the bridged frame process unit and the hardware driver; and

a Transmit frame buffer coupled to the bridged Frame Process Unit and the hardware driver.

15. The apparatus of claim 1 wherein the at least one bridge port handler means includes a Bridged frame process unit for interfacing with the second bus means;

a hardware device driver for interfacing with a LAN;

a system interface unit for interfacing with the first bus means;

a Receive frame buffer coupled to the bridged frame process unit and the hardware driver; and

a Transmit frame buffer coupled to the bridged frame process unit and the hardware driver.

16. An improved multi-port bridge for interconnecting local area networks LANs including:

a first transmission bus means for transmitting information;

at least one Bridge Port Frame Handler means coupled to said first transmission bus means;

said Bridge Port Frame Handler means receiving a frame from a LAN and extracting a destination address DA and/or a source address SA from said frame;

a Contents Address Memory CAM for storing addresses of stations connected to the LANs;

a first SRAM for storing signature information coupled to the CAM;

a transparent bridge control means coupled to said first transmission bus means and to said CAM for receiving DA and/or SA from said at least one Bridge Port Frame Handler means correlating the DA with the addresses in the CAM and upon a match, extracting associated signature information from the SRAM and forwarding the signature information to said at least one bridge port frame handler means.

17. The improved multiport bridge of claim 16 wherein the transparent bridge control means further correlates SA received from the Bridge Port Frame Handler means with address entries in the CAM and upon a match updates selected fields in a selected entry of the SRAM.

18. The improved multiport bridge of claim 16 further including:

a SRAM controller coupled to the transparent bridge control means; and

a second SRAM for storing source address SA not found in the contents address memory CAM coupled to the SRAM controller.

19. The improved multiport bridge of claim 16 wherein the SA is correlated with the station addresses stored in the CAM, if a SA match is not found, the transparent bridge control means notifies the SRAM controller which transfers unmatched SA to the second SRAM.

20. The improved multiport bridge of claim 19 further including a microprocessor coupled to the transparent bridge control means and the first transmission bus means;

said microprocessor responsive to signals from the transparent bridge control means to transfer addresses from the second SRAM into the CAM.

21. The improved multi-port bridge of claim 16 further including a means for processing Source Routing Frames coupled to the at least one Bridge Port Frame Handler;

and

a microcontroller coupling the means for processing Source Routing Frames to the transparent bridge control means.

22. The improved multi-port bridge of claim 21 wherein the means for processing Source Routing Frames includes a second transmission bus means for transporting information;

a bus arbiter coupled to the second transmission bus means; and

a packet memory coupled to the second transmission bus means.