System and method for MAC scalability and host mobility with layer-3 optimized integrated routing and bridging (IRB)

1 . A computing system, comprising:

a plurality of edge devices;

one or more processors; and

one or more computer-readable non-transitory storage media comprising instructions that, when executed by the one or more processors, cause one or more components of the computing system to perform operations comprising:

receiving, at a first edge device of the plurality of edge devices and from a first host device, an address-resolution-protocol (ARP) request;

advertising, by the first edge device and based on the ARP request, a first remote route associated with a first flag indicating the first edge device operates in a layer-3 optimized integrated-routing-and-bridging (IRB) mode;

receiving, at a second edge device of the plurality of edge devices and from the first edge device, the first remote route; and

responsive to detecting the first flag by the second edge device, installing, by the second edge device, the first remote route into a layer-2 routing information base (RIB) associated with the second edge device.

2 . The computing system of claim 1 , the operations further comprising:

identifying, by the first edge device, a second host device as a target host device;

determining, by the first edge device, the first remote route has been installed; and

transmitting, from the first edge device to the first host device, a conditional ARP response.

3 . The computing system of claim 1 , the operations further comprising:

determining, by the first edge device, that a target host device is unknown; and

triggering, by the first edge device, one or more further ARP requests configured to discover the target host device.

4 . The computing system of claim 1 , the operations further comprising:

determining, by the first edge device, that the ARP request is a unicast message comprising a first media-access-control (MAC) destination address different than a second MAC destination address of an IRB interface associated with the first edge device;

determining, by the first edge device, whether the ARP request has been punted; and

based on determining whether the ARP request has been punted:

if the ARP request has been punted, forwarding the ARP request as is by the first edge device; else

if the ARP request has not been punted, bridging the ARP request by the first edge device.

5 . The computing system of claim 1 , the operations further comprising: installing, by the second edge device, the first remote route into a layer-3 RIB and a layer-3 forwarding information base (FIB).

6 . The computing system of claim 1 , the operations further comprising one or more of:

deleting, by the second edge device, a media-access-control (MAC) address associated with the first remote route from the layer-2 RIB; and

updating, in the layer-2 RIB, an adjacency for the MAC address to point to the first edge device.

7 . The computing system of claim 1 , the operations further comprising:

receiving, at the second edge device and from a second host device, an ARP response;

advertising, by the second edge device and based on the ARP response, a second remote route associated with a second flag indicating the second edge device operates in a layer-3 optimized IRB mode;

receiving, at the first edge device and from the second edge device, the second remote route; and

responsive to detecting the second flag by the first edge device, installing, by the first edge device, the second remote route into a layer-2 RIB associated with the first edge device.

8 . The computing system of claim 1 , wherein the second edge device operates in a traditional IRB mode, the operations further comprising:

bridging a traffic exchange from the second edge device to the first edge device.

9 . The computing system of claim 1 , wherein the second edge device operates in a traditional IRB mode without ARP suppression, the operations further comprising:

bridging a traffic exchange from the first edge device to the second edge device.

10 . The computing system of claim 1 , wherein the second edge device operates in a traditional IRB mode with ARP suppression, the operations further comprising:

receiving, at the second edge device from a second host device, an ARP request;

immediately sending, from the second edge device to the second host device, an ARP response according to the ARP suppression; and

routing a traffic exchange from the first edge device to the second edge device.

11 . A method, comprising:

receiving, at a first edge device of a plurality of edge devices and from a first host device, an address-resolution-protocol (ARP) request;

advertising, by the first edge device and based on the ARP request, a first remote route associated with a first flag indicating the first edge device operates in a layer-3 optimized integrated-routing-and-bridging (IRB) mode;

receiving, at a second edge device of the plurality of edge devices and from the first edge device, the first remote route; and

responsive to detecting the first flag by the second edge device, installing, by the second edge device, the first remote route into a layer-2 routing information base (RIB) associated with the second edge device.

12 . The method of claim 11 , further comprising:

identifying, by the first edge device, a second host device as a target host device;

determining, by the first edge device, the first remote route has been installed; and

transmitting, from the first edge device to the first host device, a conditional ARP response.

13 . The method of claim 11 , further comprising:

determining, by the first edge device, that a target host device is unknown; and

triggering, by the first edge device, one or more further ARP requests configured to discover the target host device.

14 . The method of claim 11 , wherein the second edge device operates in a traditional IRB mode, the method further comprising:

bridging a traffic exchange from the second edge device to the first edge device.

15 . The method of claim 11 , wherein the second edge device operates in a traditional IRB mode without ARP suppression, the method further comprising:

bridging a traffic exchange from the first edge device to the second edge device.

16 . The method of claim 11 , wherein the second edge device operates in a traditional IRB mode with ARP suppression, the method further comprising:

receiving, at the second edge device from a second host device, an ARP request;

immediately sending, from the second edge device to the second host device, an ARP response according to the ARP suppression; and

routing a traffic exchange from the first edge device to the second edge device.

17 . A non-transitory computer-readable medium comprising instructions that are configured, when executed by a processor, to perform operations comprising:

receiving, at a first edge device of a plurality of edge devices and from a first host device, an address-resolution-protocol (ARP) request;

advertising, by the first edge device based on the ARP request, a first remote route associated with a first flag indicating the first edge device operates in a layer-3 optimized integrated-routing-and-bridging (IRB) mode;

receiving, at a second edge device of the plurality of edge devices and from the first edge device, the first remote route; and

responsive to detecting the first flag by the second edge device, installing, by the second edge device, the first remote route into a layer-2 routing information base (RIB) associated with the second edge device.

18 . The non-transitory computer-readable medium of claim 17 , the operations further comprising:

identifying, by the first edge device, a second host device as a target host device;

determining, by the first edge device, the first remote route has been installed; and

transmitting, from the first edge device to the first host device, a conditional ARP response.

19 . The non-transitory computer-readable medium of claim 17 , the operations further comprising:

determining, by the first edge device, that a target host device is unknown; and

triggering, by the first edge device, one or more further ARP requests configured to discover the target host device.

20 . The non-transitory computer-readable medium of claim 17 , wherein the second edge device operates in a traditional IRB mode, the operations further comprising:

bridging a traffic exchange from the second edge device to the first edge device.