Aggregation of mac data flows through pre-established path between ingress and egress switch to reduce number of number connections

• US 6,151,324 A
• Filed: 06/03/1996
• Issued: 11/21/2000
• Est. Priority Date: 06/03/1996
• Status: Expired due to Term

• Current Assignee: Extreme Networks, Inc.
• Original Assignee: Cabletron Systems Incorporated (Extreme Networks, Inc.)
• Inventors: Haggerty, William T., Fee, Brendan, Cioli, Jeff, Bussiere, Richard, Belser, David
• Primary Examiner(s): Kim, Kenneth S.
• Application Number:
  US08/657,414
• Time in Patent Office: 1,632 Days
• Field of Search: 370/397, 370/409, 370/355, 370/356, 370/359, 370/392, 395/200.68, 395/200.75, 395/200.57, 709/238
• US Class Current: 370/397
• CPC Class Codes: H04L 12/4608 LAN interconnection over ATM networks

Abstract

A method and apparatus are provided for connection-oriented switching in a communications network wherein a pre-established path is established between a select pair of an ingress switch and an egress switch. The use of pre-established paths enables a reduction in the total number of connections required inside the switch cloud, reduces the CPU load on trunk switches, and shortens the time for connection setup. In the embodiment described, the DA/SA fields of a MAC frame data packet are replaced with a "virtual path", which identifies the pre-established path between the ingress and egress switches. A "virtual circuit" is provided in another field of the modified packet which specifies the out-port and out-header on the egress switch for demultiplexing the modified packet upon receipt at the egress switch. The virtual circuit is exchanged between the ingress and egress switches at connection setup. The virtual path is assumed to already be in place, and known to both switches, prior to connection setup.

Claims

1. A method of forwarding a data packet along a pre-established path in a switched communications network, the method comprising:

receiving a MAC frame packet at an ingress switch, the packet including a source address of a source node and a destination address of a destination node;

determining a virtual path ID that describes the pre-established path from the ingress switch to an egress switch attached to the destination node through one or more intervening switches;

adding the virtual path ID to the packet to create a modified packet;

sending the modified packet on the pre-established path to the egress switch.

2. The method of claim 1, further comprising:

determining a virtual circuit ID for the source address and destination address;

removing the source address and destination address from the packet and adding the virtual circuit ID to create the modified packet.

3. The method of claim 1, further comprising:

upon receiving the packet at the egress switch, creating a restored MAC frame packet and forwarding the restored packet to the destination node.

4. The method of claim 1, wherein each switch on the pre-established path between the ingress switch and egress switch forwards the packet based on only the virtual path ID.

5. The method of claim 1, wherein the virtual path ID includes an identifier for the pre-established path, at least part of an address for the egress switch, and at least part of an address for the ingress switch.

6. The method of claim 2, wherein the egress switch determines the virtual circuit ID of the pre-determined path and forwards the virtual circuit ID to the ingress switch.

7. The method of claim 2, wherein the virtual circuit ID comprises an out-port and out-header on the egress switch to the destination.

8. The method of claim 2, wherein the egress switch determines the destination address based on the virtual path ID and virtual circuit ID.

9. The method of claim 2, wherein the virtual circuit ID is removed from the packet by the egress switch.

10. The method of claim 1, wherein the source address and destination address are removed from the packet at the ingress switch and replaced by the virtual path ID.

11. The method of claim 10, wherein the virtual path ID is removed from the modified packet by the egress switch and replaced by the destination address and source address determined from the virtual path ID.

12. A method of forwarding MAC frame data packets along a pre-established path in a switched communications network, the network including a plurality of source and destination end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique physical address, the method comprising the steps of:

when a first packet is received on an access port of an ingress switch, the ingress switch determining a virtual path ID that describes the pre-established path from the ingress switch to an egress switch attached to a destination end system through one or more intervening switches, modifying the first packet to include the virtual path ID and forwarding the modified packet to the egress switch on the pre-established path.

13. The method of claim 12, wherein the ingress switch replaces a destination address/source address field in the first packet with the virtual path ID, and the modified packet further includes a virtual circuit ID for determining an out-port and out-header on the egress switch to the destination end system.

14. The method of claim 12, wherein an intermediate switch on the established path between the ingress switch and egress switch, forwards the packet based upon the virtual path ID.

15. The method of claim 13, wherein the egress switch replaces the virtual path ID with the destination address and source address of the first packet, and removes the virtual circuit ID.

16. A method of determining pre-established paths in a switched communications network, wherein data packets are communicated along the paths, the network including a plurality of source and destination end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique physical address, the method comprising the steps of:

prior to a connection setup for establishing communication between a source end system and destination end system, determining the pre-established paths between different pairs of ingress and egress switches, which pre-established paths are known to the respective ingress and egress switches and each intermediate switch therebetween on the pre-established path; and

at a connection setup phase when a MAC frame data packet identifying the destination is received at an ingress switch, the ingress switch and an egress switch connected to the destination exchanging a message which identifies an out-port and out-header on the egress switch for modifying and transmitting the data packet addressed to the destination.

17. A method of forwarding a plurality of groups of data along a single pre-established path in a switched communications network, the network including a plurality of source and destination end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique physical address, the method comprising the steps of:

determining a single pre-established path between a select pair of ingress and egress switches through one or more intervening switches for forwarding a plurality of groups of data therebetween;

processing, by the ingress switch, the plurality of groups of data to be forwarded between the select pair wherein each of the plurality of groups of data represents a separate data flow; and

forwarding the plurality of groups of data along the single pre-established path.

18. A method of forwarding data packets along a pre-established path in a switched communications network, the network including a plurality of source and destination end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique MAC address, wherein data packets containing MAC addresses for the source and destination end systems are transmitted on the network, the method comprising the steps of:

replacing the MAC addresses in the data packet with a virtual path ID that describes the pre-established path from an ingress switch, connected to the source end system, to an egress switch through one or more intervening switches, the egress switch being connected to the destination end system; and

forwarding the data packet along the pre-established path.

19. A method of forwarding data packets along a pre-established path in a switched communications network, the network including a plurality of source and destination end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique MAC address, wherein data packets containing addressing data including MAC addresses for the source and destination end systems are transmitted on the network, the method comprising the steps of:

transmitting a data packet from an ingress switch, connected to a source end system, to an egress switch, connected to a destination end system, on the pre-established path from the ingress switch to the egress switch, wherein the addressing data of the data packet is reformatted only at the ingress and egress switches.

20. An apparatus for forwarding a plurality of groups of data along a single one of a plurality of pre-established paths in a switched communications network, the network including a plurality of end systems and switches connected by links, the switches having access ports connected to end systems and network ports connected to other switches, and each end system having a unique physical address, the apparatus comprising:

each one of the switches having means for maintaining a connection database of pre-established paths between select pairs of ingress and egress switches through one or more intervening switches; and

when a a plurality of groups of data is received on a port of one switch, the one switch having means for accessing its connection database to determine the single pre-established path of said plurality of pre-established paths upon which the plurality of groups of data is forwarded, and wherein each of the plurality of groups of data represents a separate data flow.