Forwarding table minimisation in Ethernet switches

• US 20070047540A1
• Filed: 08/26/2005
• Published: 03/01/2007
• Est. Priority Date: 08/26/2005
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Rockstar Consortium US LP (Rockstar Consortium Inc.)
• Inventors: Bragg, Nigel, Chen, Michael, Osswald, John, Arlfovic, Mirza
• Granted Patent: US 8,498,297 B2
• Time in Patent Office: Days
• US Class Current: 370/386
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/3018 Input queuing
• CPC Class Codes: H04L 49/3072 Packet splitting
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/354 for supporting virtual local area networks [VLAN]

Abstract

An Ethernet switch for use in an Ethernet network comprises a set of ingress ports for receiving data frames and a set of egress ports. A memory is associated with each ingress port and stores forwarding information indicating one or more of the egress ports to which data frames received by that ingress port should be forwarded. A control or management interface receives information about a network connection established, or to be established, through the switch. A switch controller causes forwarding information to be stored in a memory associated with a first ingress port which the network connection will use, on the basis of the received information about a network connection. Forwarding information is not stored in a memory associated with a second of the set of ingress ports which the network connection will not use. Preferably, the switch controller causes forwarding information to be stored only in a memory associated with the first ingress port which the network connection will use and not to be stored in a memory associated with any of the other ingress ports.

Claims

1. An Ethernet switch for use in an Ethernet network, the switch comprising:

a set of ingress ports for receiving data frames;

a set of egress ports;

a switch fabric for selectively interconnecting the ingress and egress ports;

a memory, associated with each ingress port, for storing forwarding information indicating one or more of the egress ports to which data frames received by that ingress port should be forwarded;

a control or management interface for receiving information about a network connection established, or to be established, through the switch; and

a switch controller which is arranged to cause forwarding information to be stored in a memory associated with a first ingress port which the network connection will use, on the basis of the received information about a network connection, and not to be stored in a memory associated with a second ingress port which the network connection will not use.

2. An Ethernet switch according to claim 1 wherein the switch controller is arranged to cause forwarding information to be stored only in a memory associated with the first ingress port which the network connection will use, on the basis of the received information about a network connection.

3. An Ethernet switch according to claim 1 wherein the forwarding information stored in a memory comprises a destination network address and a VLAN tag, or part thereof, of a data frame expected to be received at that ingress port and one or more egress ports to which the data frame should be forwarded.

4. An Ethernet switch according to claim 1 wherein the information comprises a destination network address and at least one of:

an IEEE 802.1Q field and an MPLS label, or part thereof, of a data frame expected to be received at that ingress port and one or more egress ports to which the data frame should be forwarded.

5. An Ethernet switch according to claim 1 wherein each ingress port has a port controller and the port controller is arranged to receive the selected forwarding information and to update the forwarding information in the memory associated with that ingress port.

6. An Ethernet network comprising a plurality of Ethernet switches according to claim 1.

7. A port card for use in an Ethernet switch of an Ethernet network in which a network connection may be established through the switch, the switch comprising a set of port cards, each port card comprising:

an ingress port for receiving data frames; and

a memory for storing forwarding information indicating one or more egress ports of the switch to which data frames received by the ingress port should be forwarded;

wherein the forwarding information stored in the memory relates only to network connections which use that ingress port.

8. A port card according to claim 7 comprising a plurality of ingress ports.

9. A port card according to claim 8 wherein the plurality of ingress ports share the same memory.

10. A port controller for an ingress port of an Ethernet switch in an Ethernet network, the switch comprising a set of ingress ports for receiving data frames, a set of egress ports, a switch controller which is arranged to receive information about connections across the network, and wherein the ingress ports each have a memory for storing forwarding information indicating one or more of the egress ports to which data frames received by that port should be forwarded, the port controller comprising control logic which is operable to:

receive forwarding information from the switch controller for a network connection which is established, or will be established, via the ingress port; and

update the forwarding information in the memory for that ingress port wherein the forwarding information is received on the basis of whether the network connection will use that ingress port.

11. An ingress port card comprising the port controller according to claim 10.

12. A switch controller for an Ethernet switch in an Ethernet network, the switch comprising a set of ingress ports for receiving data frames and a set of egress ports, each ingress port having a memory associated with it for storing forwarding information indicating one or more of the egress ports to which data frames received by that ingress port should be forwarded, the switch controller comprising control logic which is operable to:

receive information about a network connection established, or to be established, through the switch; and

cause forwarding information to be stored in a memory associated with a first ingress port which the network connection will use, on the basis of the received information about a network connection, and not to be stored in a memory associated with a second ingress port which the network connection will not use.

13. A switch according to claim 12 which is operable to cause forwarding information to only be stored in a memory associated with the first ingress port which the network connection will use on the basis of the received information about a network connection.

14. A method of managing forwarding information at an ingress port of an Ethernet switch, the switch comprising a set of ingress ports for receiving data frames, a set of egress ports and a memory associated with each ingress port for storing forwarding information indicating one or more of the egress ports to which data frames received by that ingress port should be forwarded, the method comprising:

receiving, via a control or management interface, information about a network connection established, or to be established, through the switch; and

causing forwarding information to be stored in a memory associated with a first ingress port which the network connection will use, on the basis of the received information about a network connection, and not to be stored in a memory associated with a second ingress port which the network connection will not use.

15. A method according to claim 14 which is operable to cause forwarding information to be stored only in a memory associated with the first ingress port which the network connection will use on the basis of the received information about a network connection.

16. Instructions for causing a processor at an Ethernet switch to perform the method according to claim 14.

17. A machine-readable medium carrying the instructions of claim 16.