Thursday, April 1, 2021

ARP not updating on border router from CPE changeout

Im sure this is a common issue but I don't know the terminology to look for.

My border router ARP entries aren't getting updated when a customer changes out their equipment on a passthrough port.

The topology is: Customer Firewall -> passthrough port -> Calix 844G -> Calix E7-2 -> Cisco 920 -> MPLS -> Cisco 920 -> Cisco 1002HX Border Router

Now that I know this happens, I just clear the arp entry on the border router and their new equipment works just fine. Ideally I wouldnt have to manually clear the arp entry or wait for the arp expiration.

What is the proper method for dealing with this? Lowering the arp timeout doesnt seem like a good idea.



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