ARP flood suppression

ARP flood suppression reduces ARP request broadcasts by enabling the VTEP to reply to ARP requests on behalf of VMs.

As shown in Figure 8, this feature snoops ARP packets to populate the ARP flood suppression table with local and remote MAC addresses. If an ARP request has a matching entry, the VTEP replies to the request on behalf of the VM. If no match is found, the VTEP floods the request to both local and remote sites.

ARP flood suppression uses the following workflow:

1. VM 1 sends an ARP request to obtain the MAC address of VM 7.

2. VTEP 1 creates a suppression entry for VM 1, and floods the ARP request in the VXLAN.

3. VTEP 2 and VTEP 3 de-encapsulate the ARP request. The VTEPs create a suppression entry for VM 1, and broadcast the request in the local site.

4. VM 7 sends an ARP reply.

5. VTEP 2 creates a suppression entry for VM 7 and forwards the ARP reply to VTEP 1.

6. VTEP 1 de-encapsulates the ARP reply, creates a suppression entry for VM 7, and forwards the ARP reply to VM 1.

7. VM 4 sends an ARP request to obtain the MAC address of VM 1 or VM 7.

8. VTEP 1 creates a suppression entry for VM 4 and replies to the ARP request.

9. VM 10 sends an ARP request to obtain the MAC address of VM 1.

10. VTEP 3 creates a suppression entry for VM 10 and replies to the ARP request.