TRIPLE-TIER ANYCAST ADDRESSING

• US 20080186968A1
• Filed: 02/02/2007
• Published: 08/07/2008
• 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: Farinacci, Dino, Edsall, Thomas
• Granted Patent: US 8,259,720 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• 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. A method for processing, at a first layer 2 switch, a hardware address request received from a second layer 2 switch, wherein the hardware address request is directed to a first router in an emulated switch, wherein the emulated switch comprises a plurality of routers, and wherein the first layer 2 switch is an edge switch, the method comprising:

forwarding the hardware address request to the first router;

receiving a hardware address reply from the first router, the hardware address reply including an anycast hardware address shared between each router in the emulated switch;

adding a layer 2 network header to the hardware address reply; and

forwarding the hardware address reply to a third layer 2 switch.

2. The method of claim 1, further comprising:

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

3. The method of claim 2, 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. A method comprising

receiving, at a first layer 2 switch, a packet, from a first router in an emulated switch, wherein the emulated switch comprises a plurality of routers, wherein the packet includes an anycast hardware address shared between each router in the emulated switch, and wherein the first layer 2 switch is an edge switch;

adding a layer 2 network header to the packet; and

forwarding the packet to a second layer 2 switch.

5. The method of claim 4, further comprising:

adding the anycast hardware address to a table along with an identification of the edge switch.

6. The method of claim 5, 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.

7. A method for processing, at a layer 2 edge switch in a network containing a plurality of layer 2 switches, a packet received from a host, wherein the packet includes an anycast hardware address of an emulated switch, wherein the emulated switch comprises a plurality of routers, the method comprising:

determining a switch identifier for the emulated switch using the anycast hardware address;

adding a header to the packet, the header including the switch identifier; and

forwarding the packet to another layer 2 switch along a shortest path from the layer 2 edge switch to the emulated switch.

8. The method of claim 7, wherein the determining includes looking up the anycast hardware address in a table to retrieve the switch identifier.

9. The method of claim 7, wherein the shortest path is determined based on a source address of the packet, using a hash table, if the shortest path cannot be determined based on distance due to a tie between two or more paths.

10. A method for processing, at a layer 2 edge switch in a network containing a plurality of layer 2 switches, a packet received from a host, wherein the packet includes a destination anycast hardware address of an emulated switch, and wherein the emulated switch comprises a plurality of routers, the method comprising:

determining a switch identifier for the emulated switch using the anycast hardware address;

adding a header to the packet, the header including the switch identifier;

determining a shortest operative path from the layer 2 edge switch to the emulated switch; and

forwarding the packet to another layer 2 switch via the shortest operative path.

11. The method of claim 10, wherein the determining includes looking up the anycast hardware address in a table to retrieve the switch identifier.

12. The method of claim 10, wherein the shortest path is determined based on the source address of the packet, using a hash table, if the shortest path cannot be determined based on distance due to a tie between two or more paths.

13. The method of claim 10, wherein the network containing a plurality of layer 2 switches is a Data Center Ethernet (DCE) network.

14. The method of claim 10, wherein the header is a MAC-in-MAC header.

15. The method of claim 10, wherein the routers do not run a hot standby routing protocol.

16. A layer 2 edge switch for use in a network containing layer 2 switches, the layer 2 edge switch comprising:

one or more line cards, wherein at least one of the one or more line cards is configured to perform the following, upon receipt of a packet from a host, wherein the packet includes a destination anycast hardware address of an emulated switch, and wherein the emulated switch comprises a plurality of routers;

determine a switch identifier for the emulated switch using the anycast hardware address;

add a header to the packet, the header including the switch identifier;

determine a shortest operative path from the layer 2 edge switch to the emulated switch; and

forward the packet to another layer 2 switch via the shortest operative path.

17. The layer 2 edge switch of claim 16, wherein the layer 2 edge switch is a DCE switch.

18. The layer 2 edge switch of claim 16, wherein the header is a MAC-in-MAC header.

19. An apparatus comprising:

means for receiving, at a layer 2 edge switch in a network containing a plurality of layer 2 switches, a packet from a host, wherein the packet includes a destination anycast hardware address of an emulated switch, and wherein the emulated switch comprises a plurality of routers;

means for determining a switch identifier for the emulated switch using the anycast hardware address;

means for adding a header to the packet, the header including the switch identifier;

means for determining a shortest operative path from the layer 2 edge switch to the emulated switch; and

means for forwarding the packet to another layer 2 switch via the shortest operative path.

20. The apparatus of claim 19, wherein the network containing a plurality of layer 2 switches is a Data Center Ethernet (DCE) network.