METHOD & APPARATUS FOR FORWARDING TABLE REDUCTION

• US 20110292939A1
• Filed: 05/28/2010
• Published: 12/01/2011
• Est. Priority Date: 05/28/2009
• Status: Active Grant

• Current Assignee: Dell Marketing Corporation (Dell Technologies Inc.)
• Original Assignee: Force10 Networks, Inc. (Dell Technologies Inc.)
• Inventors: Subramaian, Krishnamurthy, Viswanathan, Arun
• Granted Patent: US 8,259,726 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 45/54 Organization of routing tables

Abstract

A LAN includes a router that is connected to two or more racks of servers and each of the servers can support a plurality of virtual machines. The router is configured to forward data packets based on IP destination addresses or based on destination MAC addresses and builds and maintains forwarding tables in support of data packet forwarding in the layer 3 and the layer 2 network environment. In support of layer 2 forwarding, the router builds and maintains an aggregated MAC switching table that is comprise of a subset of the table entries typically needed to switch packets to their destination, and in support of layer 3 forwarding, the router or switch builds and maintains an aggregated ARP forwarding table that is comprised of a subset of the table entries typically needed to forward packets to their destination.

Claims

1. A method for reducing the size of a first forwarding table, comprising:

a packet network device learning at least one network address for each of a plurality of network nodes and storing in the first forwarding table the at least one network address in association with a portID on which the at least one address is learned; and

determining that at least two of the network addresses stored in the first forwarding table meet a predetermined set of network address aggregation conditions, aggregating the at least two network addresses into a single, aggregated network address and storing the aggregated network address in a second forwarding table.

2. The method of claim 1, wherein the size of the first and second forwarding tables is determined by the number of table entries.

3. The method of claim 2, wherein aggregated table entries comprising the second forwarding table do not include a destination address.

4. The method of claim 2, wherein the second forwarding table entries are comprised of one or more of a network address, a VLANID and a portID.

5. The method of claim 4, wherein the network address is one or both of an IP destination address and a destination MAC address.

6. The method of claim 5, wherein the destination MAC address is comprised of an organizationally unique identifier and at least a portion of an IP destination address.

7. The method of claim 1, wherein the at least one network address stored in association with a portID comprises one forwarding table entry.

8. The method of claim 1, wherein the set of predetermined network address aggregation conditions are selected to aggregate network addresses without altering the forwarding behavior of the packet network device.

9. The method of claim 1 wherein the set of predetermined network address aggregation conditions is comprised of a condition that at least two or more network addresses are associated with the same egress portID, a condition that two or more network addresses are unicast and have an administrative bit set and a condition that two or more network addresses match.

10. The method of claim 9 further comprising a condition that two or more network addresses are in a contiguous address range.

11. The method of claim 1 wherein the aggregated network address is stored in a second forwarding table in association with the portID.

12. The method of claim 9 wherein matching the two or more network addresses includes either matching address prefixes or suffixes.

13. The method of claim 1 further comprising a derivation table comprising packet network device information used to derive a destination address.

14. The method of claim 13 wherein the packet network device information used to derive the destination address is comprised of an organizationally unique identifier and at least a portion of the IP destination address associated with each one of the plurality of network nodes.

15. A packet network device, comprising:

ingress and egress ports;

a packet processor; and

a control processor for building and maintaining a full forwarding table comprising two or more network addresses and, subject to a set of network address aggregation conditions, for determining that two or more of the network addresses can be aggregated and entering the aggregated network addresses into an aggregated forwarding table stored in memory associated with the packet processor which uses the aggregated addresses to forward packets received over any one of the ingress ports by the packet network device to their destination over the correct egress port.

16. The packet network device of claim 15 wherein the aggregated forwarding table stored in the packet processor memory is comprised of a network address, a VLANID and an portID.

17. The packet network device of claim 15 wherein the aggregated forwarding table stored in the packet processor memory is comprised of an organizationally unique identifier (OUI) and at least a portion of a destination IP address.

18. The packet network device of claim 15 performs one or both of a network routing functionality and a network switching functionality.

19. The packet network device of claim 15 wherein the packet processor is comprised of packet forwarding functionality and an aggregated forwarding table stored in on-board memory that is maintained by the control processor.

20. The packet network device of claim 19 wherein the packet processor includes a derivation table comprising packet network device information used to derive a destination address.

21. The packet network device of claim 20 wherein the packet processor uses the packet network device information in the derivation table to derive a destination address for a packet received by the packet network device over any one of the ingress ports when the destination address of incoming packet matches an aggregated network address included in the aggregated forwarding table.