Method and apparatus for router aggregation

• US 8,009,668 B2
• Filed: 08/17/2004
• Issued: 08/30/2011
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Wakumoto, Shaun Kazuo, Bare, Ballard Claude
• Primary Examiner(s): Ton; Dang T
• Assistant Examiner(s): O CONNOR, BRIAN T
• Application Number:
  US10/919,760
• Publication Number:
  US 20060039385A1
• Time in Patent Office: 2,569 Days
• Field of Search: 370/389, 370/397, 370/400, 370/401, 709/225, 709/241
• US Class Current: 370/389
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 45/58 Association of routers
• CPC Class Codes: H04L 45/586 of virtual routers

Abstract

One embodiment disclosed relates to a method of routing a packet by way of a router aggregation. A packet is received from outside the aggregation by an initially receiving router/switch unit. Router functions are performed by the initially receiving router unit, including modification of the packet. The packet is then sent to a layer 2 network of the aggregation, wherein switching functions are performed on the packet. Another embodiment disclosed relates to a cooperative aggregation of router/switch units. The aggregation includes a plurality of the router/switch units, and a switching network interconnecting the units. The cooperative aggregation functions as a single router from a perspective of an external network device coupled to the system.

Claims

1. A cooperative aggregation of router/switch units, the cooperative aggregation comprising:

a plurality of the router/switch units;

a switching network including and interconnecting said plurality of router/switch units,

wherein the cooperative aggregation is configured to function as a single router from a perspective of an external network device coupled to the cooperative aggregation,

wherein each router/switch is configured such that, if the router/switch is an initial router/switch unit that receives a packet from outside the aggregation, then the router/switch is configured to perform routing functions, including modification of the source and destination Media Access Control (MAC) addresses, with respect to the packet, and if the router/switch unit is not the initial router/switch unit in the aggregation to receive the packet, then the router/switch unit is configured to not perform routing functions with respect to the packet;

each router/switch sharing information with the other router/switch units of the aggregation using a first protocol such that each router/switch is able to determine whether a destination Internet Protocol (IP) address for a packet is within an IP subnet that is directly or externally connected to one of the router/switches of the aggregation.

2. The cooperative aggregation of claim 1, wherein each router/switch unit comprises an Internet protocol router adapted to function as part of the aggregation.

3. The cooperative aggregation of claim 1, wherein interconnections of the switching network are configured to provide multiple paths to communicate packets between any two router/switch units.

4. The cooperative aggregation of claim 3, wherein the switching network comprises a switching mesh.

5. The cooperative aggregation of claim 1, further comprising:

a second protocol configured to share Address Resolution Protocol (ARP) cache information between the router/switch units of the aggregation.

6. The cooperative aggregation of claim 5, wherein the ARP cache information includes cached MAC addresses for end hosts in the directly-connected subnets and cached MAC addresses for next-hop routers in the externally-connected subnets.

7. The cooperative aggregation of claim 1, wherein the routing functions include looking up a destination IP address from the packet in a routing table.

8. The cooperative aggregation of claim 7, wherein one or more of the other router/switch units are configured to perform switching with respect to that packet.

9. The cooperative aggregation of claim 1, wherein each router/switch unit is configured such that, if the router/switch unit is an initial router/switch unit that receives a multicast packet from outside the aggregation, then the router/switch unit is configured to use a broadcast map to send the multicast packet to all other router/switch units of the aggregation, and if the router/switch unit is not the initial router/switch unit that receives the multicast packet from outside the aggregation, then the router/switch unit is configured to replicate and forward the multicast packet out of ports external to the aggregation where multicast joins have occurred.

10. A method of routing a packet by way of an aggregation of router/switch units, the method comprising:

sharing routing information between the router/switch units of the aggregation such that each router/switch is capable of determining whether a packet destination Internet Protocol (IP) address is within an IP subnet that is directly or externally connected to one of the other router/switch units of the aggregation;

receiving a packet from outside the aggregation by an initially receiving router/switch unit;

performing router functions by the initially receiving router unit, including modification of the source and destination Media Access Control (MAC) addresses of the packet; and

sending the packet to a layer 2 network of the aggregation, wherein switching functions, but no router functions, are performed on the packet.

11. The method of claim 10, further comprising layer 2 switching of the packet by other router/switch units of the aggregation.

12. The method of claim 11, wherein each router/switch unit comprises an Internet Protocol router adapted to function as part of the aggregation.

13. The method of claim 10, wherein the layer 2 network provide multiple paths to communicate packets between any two router/switch units.

14. The method of claim 13, wherein the layer 2 network comprises a switching mesh.

15. The method of claim 10, further comprising:

sharing Address Resolution Protocol (ARP) cache information between the router/switch units of the aggregation.

16. The method of claim 15, wherein the ARP cache information includes cached MAC addresses for end hosts in the directly-connected subnets and cached MAC addresses for next-hop routers in the externally-connected subnets.

17. An apparatus configured to route a packet as part of a an aggregation of router/switch units, the apparatus comprising:

means for sharing routing information between the router/switch units such that each router/switch unit in the aggregation is capable of determining whether a packet destination Internet Protocol (IP) address is within an IP subset that is directly or externally connected to one of the other router/switch units of the aggregation;

means for receiving a packet from outside the aggregation by an initially receiving router/switch unit;

means for performing router functions by the initially receiving router unit, including looking-up a destination internet protocol address from the packet in a routing table and modification of the source and destination Media Access Control (MAC) addresses of the packet; and

means for sending the packet to a layer 2 network of the aggregation wherein switching functions, but no routing functions, are performed on the packet.

18. The apparatus of claim 17, wherein the routing functions performed by the initially receiving router unit further include decrementing an IP time-to-live and re-computing an IP header check-sum.

19. The apparatus of claim 17, wherein the cooperative aggregation functions as a single router from a perspective of an external network device.