Connecting layer-2 domains over layer-3 networks

Patent metadata

Field	Value
Publication number	US-9363225-B2
Application number	US-201213349376-A
Country	US
Kind code	B2
Filing date	Jan 12, 2012
Priority date	Jan 12, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

In one embodiment, a method includes building an address resolution cache for a layer-3 router in a first layer-2 datacenter, where the address resolution cache includes a plurality of entries, each of the entries containing a host network address, a host hardware address, and a switch identifier for a switch serving a host, intercepting an address resolution flood within the first layer-2 datacenter that seeks address resolution for a host in a second layer-2 datacenter, and generating a response to the address resolution flood that indicates a source in the second layer-2 datacenter, where data indicating the source in the second layer-2 datacenter is accessed from the address resolution cache.

First claim

What is claimed is:

1. A method comprising:
performing the following actions in a layer-3 router in a first layer-2 datacenter:
building an address resolution cache for the layer-3 router in the first layer-2 datacenter, where the address resolution cache includes a plurality of entries, each of the entries containing a host network address, a host hardware address, and a switch identifier for a switch serving a host;
intercepting an address resolution flood within the first layer-2 datacenter that seeks address resolution for a host in a second layer-2 datacenter; and
generating a response to the address resolution flood that indicates a source of the response is a switch in the second layer-2 datacenter, where data indicating the source in the second layer-2 datacenter is accessed from the address resolution cache.

2. The method of claim 1 further comprising:
implementing a table in the layer-3 router for a list of switch identifiers; and
accessing at least one of the switch identifiers to send a frame from a first switch in the first layer-2 datacenter to a second switch in the second layer-2 datacenter over a layer-3 network.

3. The method of claim 2 further comprising:
building the list of switch identifiers by examining traffic at the layer-3 router for the switch identifiers; and
advertising the switch identifiers to a layer-3 router in the second layer-2 datacenter.

4. The method of claim 1 in which the layer-3 router comprises an Overlay Transport Virtualization (OTV) router.

5. The method of claim 1 in which the hardware address comprises a MAC address.

6. The method of claim 1 in which the network address comprises an IP address.

7. The method of claim 1 further comprising:
advertising the address resolution cache to a layer-3 router in the second layer-2 datacenter.

8. The method of claim 1 in which building the address resolution cache comprises:
in response to receiving an address resolution request at the layer-3 router from a source host that is not included in the address resolution cache, caching a hardware address, a network address, and a switch ID for the source host; and
caching address resolution data that is advertised by a layer-3 router in the second layer-2 datacenter.

9. The method of claim 1 in which building the address resolution cache comprises:
caching data from address resolution responses received from the second layer-2 data center.

10. A computer program product having a non-transitory computer readable medium tangibly recording computer program logic, the computer program product comprising:
code to perform the following actions in a layer-3 router in a first layer-2 datacenter:
build an address resolution cache for a layer-3 router in a first layer-2 datacenter, where the address resolution cache includes a plurality of entries, each of the entries containing a host network address, a host hardware address, and a switch identifier for a switch serving a host;
intercept an address resolution flood within the first layer-2 datacenter that seeks address resolution for a host in a second layer-2 datacenter; and
generate a response to the address resolution flood that indicates a source of the response is a switch in the second layer-2 datacenter, where data indicating the source in the second layer-2 datacenter is accessed from the address resolution cache.

11. The computer program product of claim 10 further comprising:
code to implement a table in the layer-3 router for a list of switch identifiers; and
code to access at least one of the switch identifiers to send a frame from a first switch in the first layer-2 datacenter to a second switch in the second layer-2 datacenter over a layer-3 network.

12. The computer program product of claim 11 further comprising:
code to build the list of switch identifiers by examining traffic at the layer-3 router for the switch identifiers; and
code to advertise the switch identifiers to a layer-3 router in the second layer-2 datacenter.

13. The computer program product of claim 10 in which the layer-3 router comprises an Overlay Transport Virtualization (OTV) router.

14. The computer program product of claim 10 in which the hardware address comprises a MAC address.

15. The computer program product of claim 10 in which the network address comprises an IP address.

16. The computer program product of claim 10 further comprising:
code to advertise the address resolution cache to a layer-3 router in the second layer-2 datacenter.

17. The computer program product of claim 10 in which building the address resolution cache comprises:
code to, in response to receiving an address resolution request at the layer-3 router from a source host that is not included in the address resolution cache, cache a hardware address, a network address, and a switch ID for the source host; and
code to cache address resolution data that is advertised by a layer-3 router in the second layer-2 datacenter.

18. The computer program product of claim 10 in which building the address resolution cache comprises:
code to cache data from address resolution responses received from the second layer-2 data center.

Assignees

• Moreno Victor
• Rao Dhananjaya
• Sane Sanjay
• Merchant Sameer
• Grover Hasmit
• Cisco Tech Inc

Inventors

• Moreno Victor
• Rao Dhananjaya
• Sane Sanjay
• Merchant Sameer
• Grover Hasmit

Classifications

• H04L45/00

  Routing or path finding of packets in data switching networks (routing or path finding in wireless networks H04W40/00) · CPC title

• H04L45/66

  Layer 2 routing, e.g. in Ethernet based MAN's · CPC title

• H04L45/742

  Route cache; Operation thereof · CPC title

• H04L61/103 Primary

  across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP] · CPC title