Triple-tier anycast addressing

• US 8,743,738 B2
• Filed: 08/13/2012
• Issued: 06/03/2014
• Est. Priority Date: 02/02/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Edsall, Thomas James, Farrinacci, Dino
• Primary Examiner(s): Weidner, Timothy J
• Application Number:
  US13/584,546
• Publication Number:
  US 20120300782A1
• Time in Patent Office: 659 Days
• Field of Search: None
• US Class Current: 370/254
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 2101/622 Layer-2 addresses, e.g. medium access control [MAC] addresses
• CPC Class Codes: H04L 2101/677 Multiple interfaces, e.g. multihomed nodes
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/58 Association of routers
• CPC Class Codes: H04L 45/74 Address processing for routing
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/552 by ensuring the integrity of packets received through redundant connections
• CPC Class Codes: H04L 49/604 Hybrid IP/Ethernet switches
• CPC Class Codes: H04L 49/70 Virtual switches
• CPC Class Codes: H04L 61/103 across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]

Abstract

In one embodiment, a solution is provided wherein redundant routers are treated as a single emulated switch. When a packet is received at a layer 2 edge switch from a host, the layer 2 edge switch may determine a switch identifier for the emulated switch using a destination anycast hardware address contained in the packet. The anycast hardware address may identify an emulated switch comprising a plurality of routers. Then a header may be added to the packet, the header including the switch identifier. Following that, the packet may be forwarded to another layer 2 switch along a shortest path from the layer 2 edge switch to the emulated switch.

Claims

1. An apparatus, comprising:

a processor; and

a memory, at least one of the processor or the memory being adapted for;

receiving an address request at a first layer 2 switch from a second layer 2 switch, wherein the address request is directed to an emulated switch, wherein the emulated switch comprises a plurality of routers, wherein each of the routers of the emulated switch is assigned a same address;

forwarding the address request to a first one of the routers of the emulated switch;

receiving an address reply from the first router, the address reply including an address that corresponds to the same address that is assigned to each of the routers of the emulated switch; and

transmitting the address reply.

2. The apparatus of claim 1, at least one of the processor or the memory being adapted for performing steps, further comprising:

adding the address to a table along with an identification of the first layer 2 switch.

3. The apparatus of claim 2, at least one of the processor or the memory being adapted for performing steps, further comprising:

synchronizing the table with one or more tables associated with one or more layer 2 switches other than the first layer 2 switch.

4. The apparatus of claim 1, wherein transmitting the address reply comprises forwarding the address reply to a third layer 2 switch, wherein the first layer 2 switch, the second layer 2 switch, and the third layer 2 switch belong to a same network that includes a plurality of layer 2 switches that include the first, second, and third layer 2 switches, and wherein each of the routers of the emulated switch is configured as a layer 3 gateway device of the same network for forwarding data between devices of this same network and devices outside this same network, via one or more of the switches of this same network.

5. The apparatus of claim 1, wherein the routers do not run a redundancy protocol.

6. The apparatus of claim 1, wherein the same address is a Media Access Controller (MAC) address.

7. The apparatus of claim 1, at least one of the processor or the memory being further adapted for performing steps, comprising:

adding a layer 2 network header to the address reply prior to transmitting the address reply.

8. The apparatus of claim 1, wherein the first layer 2 switch is an edge switch that has an interface with at least one of the routers of the emulated switch.

9. The apparatus of claim 1, wherein the address is an anycast address shared between each router in the emulated switch.

10. A method, comprising:

receiving an address request at a first layer 2 switch from a second layer 2 switch, wherein the address request is directed to an emulated switch, wherein the emulated switch comprises a plurality of routers, wherein each of the routers of the emulated switch is assigned a same address;

forwarding the address request to a first one of the routers of the emulated switch;

receiving an address reply from the first router, the address reply including an address that corresponds to the same address that is assigned to each of the routers of the emulated switch; and

transmitting the address reply.

11. The method of claim 10, further comprising adding the address to a table along with an identification of the first layer 2 switch.

12. The method of claim 11, further comprising synchronizing the table with one or more tables associated with one or more layer 2 switches other than the first layer 2 switch.

13. The method of claim 10, wherein transmitting the address reply comprises forwarding the address reply to a third layer 2 switch, wherein the first layer 2 switch, the second layer 2 switch, and the third layer 2 switch belong to a same network that includes a plurality of layer 2 switches that include the first, second, and third layer 2 switches, and wherein each of the routers of the emulated switch is configured as a layer 3 gateway device of the same network for forwarding data between devices of this same network and devices outside this same network, via one or more of the switches of this same network.

14. The method of claim 10, wherein the first layer 2 switch is an edge switch that has an interface with at least one of the routers of the emulated switch.

15. The method of claim 10, wherein the address is an anycast address shared between each router in the emulated switch.

16. Software encoded on a non-transitory memory, the software including instructions that when executed are operable to:

receive an address request at a first layer 2 switch from a second layer 2 switch, wherein the address request is directed to an emulated switch, wherein the emulated switch comprises a plurality of routers, wherein each of the routers of the emulated switch is assigned a same address;

forward the address request to a first one of the routers of the emulated switch;

receiving an address reply from the first router, the address reply including an address that corresponds to the same address that is assigned to each of the routers of the emulated switch; and

transmit the address reply.

17. The software of claim 16, wherein the first layer 2 switch is an edge switch that has an interface with at least one of the routers of the emulated switch.

18. The software of claim 16, wherein the address is an anycast address shared between each router in the emulated switch.

19. The software of claim 16, further comprising instructions that when executed are operable to add the address to a table along with an identification of the first layer 2 switch.

20. The software of claim 19, further comprising instructions that when executed are operable to synchronize the table with one or more tables associated with one or more layer 2 switches other than the first layer 2 switch.