MP-BGP EVPN ARP Suppression
Shehab Wagdy Nagy
Cloud Enthusiast: AWS | CCIE | SDN Solutions | ACI | Network Automation Enthusiast
What is ARP suppression?
ARP suppression is MP-BGP EVPN feature to reduce broadcast flooding caused by ARP request.
Why ARP suppression?
As we learned so far, that one of the aim of the MP-BGP EVPN is to reduce the network flooding as much as possible through different features like:
Today will introduce new features which will reduce another kind of network flooding which is ARP flooding.
MP-BGP EVPN control plane provides ARP suppression feature which will reduce broadcast flooding in the network.
How it Works?
When you enable the ARP suppression feature for a VNI, each VTEP maintains an ARP suppression cache table for known IP hosts and their associated MAC addresses in the VNI segment.
When an end host in the VNI sends and ARP request for another end host IP address, its local VTEP intercept the ARP request and check the destination IP address in the ARP suppression cache table. If it find a match, the Local VTEP sends ARP response to the local host on behalf of the remote end host. The local host learns the MAC address of the remote end host.
If the local VTEP doesn't find the remote host address in its ARP suppression cache table, So it will flood the ARP request to all VTEPs in the VNI.
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Most of time this scenario is happening once for the silent hosts, as these device are connected to the leaf switch but doesn't send any traffic in the network, until another host send ARP request for its address. So in this case the Leaf switch will learn this silent host information and will distribute through MP-BGP EVPN control plane to all other VTEPs.
Example:
So now we understand how ARP suppression is working and its benefits and how it reduces the ARP flooding in the network.
Resources:
#VXLAN #MPBGPEVPN #EVPN #ACI #ARPSuppression