Transparent interconnector of LANs by an ATM network

• US 5,818,842 A
• Filed: 09/16/1996
• Issued: 10/06/1998
• Est. Priority Date: 01/21/1994
• Status: Expired due to Fees

• Current Assignee: Alcatel Canada Inc. (Nokia Corporation)
• Original Assignee: Newbridge Networks Corporation (Nokia Corporation)
• Inventors: Burwell, Wayne, Watt, James, Glendinning, Duncan, Behki, Nutan, Duxbury, Tom, Zywicki, Eugene, Galway, Keith, Coomber, Dave
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): RAO, SEEMA SRINIVAS
• Application Number:
  US08/676,256
• Time in Patent Office: 750 Days
• Field of Search: 370/241-244, 370/246, 370/249, 370/250, 370/351, 370/389, 370/392, 370/395-398, 370/399, 370/400, 370/401, 370/409, 370/412, 370/413, 370/419, 370/420, 370/422, 370/463, 370/474, 370/465, 395/309
• US Class Current: 370/397
• CPC Class Codes: H04L 12/4608 LAN interconnection over ATM networks
• CPC Class Codes: H04L 2012/5615 Network termination, e.g. NT1, NT2, PBX
• CPC Class Codes: H04L 2012/5618 Bridges, gateways [GW] or interworking units [IWU]
• CPC Class Codes: H04L 2012/5625 Operations, administration and maintenance [OAM]
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/5658 using the AAL5
• CPC Class Codes: H04L 49/309 Header conversion, routing tables or routing tags
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A computer communications network comprises a plurality of interconnected ATM switches forming a WAN or LAN area network over which ATM cells are transmitted, and a plurality of user devices including LAN interface adapters for connection to one or more to local area networks (LANs). An interface device connects at least some of the respective ATM switches to the LAN interface adapters. The interface adapts the ATM cells for transport over the LANS. The user devices can thus communicate through the LAN interface adapters transparently with the wide area network.

Claims

1. A computer communications system comprising:

an ATM network over which ATM cells are transmitted trough a plurality of interconnected ATM switches;

a plurality of user devices attached to the system at least some of said user devices including LAN interface adapters for connection to said ATM network through one or more local area networks (LANs);

interface means between said ATM network and said user devices storing the location of said user devices, said interface means between said ATM network and said user devices that are connected to LANs adapting LAN traffic for transport to and from said ATM network; and

a centralized route server connected to said ATM network storing address data pertaining to the location of said user devices attached to the system, said centralized route server exchanging data over said ATM network with said interface means to learn the locations of said user devices and to distribute such information to said user devices so as to permit said interface means to establish direct transparent communication on demand using a dynamic mesh of ATM connections between a said user device connected thereto and another said user device attached to the system.

2. A computer communications system as claimed in claim 1, wherein said interface means comprises means for encapsulating said ATM cells in LAN frames for delivery of said ATM cells directly to the LAN interface adapters of said user devices so as to permit said user devices to communicate with user devices connected directly to the ATM network.

3. A computer communications system as claimed in claim 2, wherein said LAN interface adapters are Ethernet adapters, and said encapsulating means encapsulates said ATM cells in Ethernet frames for delivery to said Ethernet adapters.

4. A computer communications system as claimed in claim 1, wherein said interface means provide bridging, network-layer forwarding and LAN emulation functions to permit transparent communication between any of said user devices attached to the system.

5. A computer communications system as claimed in claim 1, further comprising monitoring means for permitting remote monitoring of said interface means, said remote monitoring means transmitting data including errors from a monitored port over said network to a remote monitoring port to replicate the data from said monitored port at said remote monitoring port, whereby tests can be conducted on said monitored port remotely as if on-site.

6. A computer communications system as claimed in claim 5, wherein it further comprises means for tagging monitored packets to prevent them from being treated as normally received packets by the receiving interface means.

7. A computer communications system as claimed in claim 3, wherein it comprises means for exchanging management information frames between said interface means and said user devices, whereby a predetermined amount of data is sent by a device receiving a management information frame before the management information frame is returned to the interface means, which then sends out a predetermined amount of data before passing on the management information frame.

8. A computer communications system as claimed in claim 1, wherein it that said interface means comprise a plurality of ports for connection to respective local area network adapters;

means for receiving incoming LAN frames at any one of said ports;

ATM segmentation means for creating outgoing ATM cells;

means for transmitting the outgoing ATM cells over an ATM network;

means for receiving incoming ATM cells from the ATM network;

re-assembly means for re-assembling LAN frames from incoming ATM cells; and

frame queuing and transmission means for transmitting outgoing LAN frames over a selected said port.

9. A computer communications system as claimed in claim 8, further comprising bypass means for directing local LAN traffic directly from said LAN receiving means to said LAN frame queuing and transmission means.

10. A computer communications system as claimed in claim 8, wherein said means for receiving incoming LAN frames includes buffer means for buffering incoming LAN frames, said buffer means including means for reading MAC headers in the incoming LAN frames, a shared segmenter RAM for storing LAN frames ready for segmentation, and a transfer engine for initiating transfer of said frames from said buffer means to said segmenter RAM.

11. A computer communications system as claimed in claim 10, wherein said buffer means are incorporated in Media Access Controllers (MACs).

12. A computer communications system as claimed in claim 10, wherein said frame queuing and transmission means also includes a shared reassembler RAM and an independent buffer associated with the selected outgoing port.

13. A computer communications system as claimed in claim 10, wherein said buffer means output data to said ATM segmentation means on n-bit wide buses, said device further comprising a translation engine for ensuring DMA packet transfer between said buffer means and said ATM segmentation means.

14. A computer communications system as claimed in claim 10, wherein said translation engine comprises means for discarding, bridging or network layer forwarding incoming LAN packets, means for encapsulating the packets for ATM layer adaptation, and means for setting up a virtual channel through the ATM network.

15. A computer communications system as claimed in claim 14, wherein said translation comprises a RISC processor.

16. A computer communications system as claimed in claim 15, wherein said segmentation means comprises an ATMizer, segmenter RAM on a primary bus thereof, high speed pointer memory on a secondary bus, and a shared memory to said re-assembly means.

17. A computer communications system as claimed in claim 8, wherein port availability is provided as a bit mask derived from hardware signals and data availability is presented as a bit mask in a packet address.

18. A computer communications system as claimed in claim 17, further comprising a priority encoder with round-robin priority for returning a port with the next highest priority in the event of unservicibility of the current queue.

19. A computer communications system as claimed in claim 8, wherein said re-assembly means includes means for snooping the incoming first cell and deriving the destination MAC address therefrom, and means for appending the thus-derived address to outgoing frames.

20. A computer communications system as claimed in claim 8, wherein said segmentation means includes a look-up engine that snoops incoming frames and forwards frame data to said segmentation means.

21. A computer communications system as claimed in claim 1, wherein it further comprises a centralized OAM resource, and OAM cells are extracted in an ATM switch from an ATM cell stream and redirected through the ATM network to said centralized OAM resource for processing.

22. A computer communications system as claimed in claim 1, wherein each port in the ATM switch comprises a RAM and hardware processing engine that interprets control cells merged into the ATM stream to configure ingress and egress connections and send responses to status requests.

23. A computer communications system as claimed in claim 1, wherein said said route server also performs admission control in accordance with rules established by a system administrator.

24. A computer system as claimed in claim 1, wherein said interface means establish communication over said ATM network by establishing a switched virtual channel therethrough.

25. A method of establishing communications between user devices connected to local area networks (LANs) through LAN adapters comprising the steps of:

providing an ATM network over which ATM cells are transmitted through a plurality of interconnected ATM switches;

providing interface means between said local area networks and said ATM network, said interface means adapting LAN traffic for transport to and from said ATM network;

storing address data pertaining to the location of said user devices attached to the system in a centralized route server connected to said ATM network; and

exchanging address data over said ATM network with said interface means to learn the locations of said user devices and to distribute such information to said user devices so as to permit said interface means to establish direct transparent communication on demand using a dynamic mesh of ATM connections between a said user device connected thereto and another said user device attached to the system.

26. A method as claimed in claim 25, wherein said interface means set up switched virtual connections through said ATM network to establish communication therebetween based on address data received from said centralized route server.

27. A method as claimed in claim 25 wherein said interface means provide bridging, network layer forwarding and LAN emulation functions.