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New Member

Updating ARP tables in routers/switches

I'm going to replace a 2600 router. The new router will have the same configuration as the former one. Of course, the MAC address for IP addresses on the Ethernet interfaces will be different. What is the fastest way to update the arp tables on those Ethernet segments? Gratuitous ARP? My colleage was suggesting the 'IP alias' command. However, I'm not sure how that would work.

As always, thanks for the assistance.


VIP Purple

Re: Updating ARP tables in routers/switches

Hello Mike,

what specific problem are you running into ? If you replace the router, the MAC addresses of the interfaces will be learned immediately, so that should not be a problem, and manual intervention should not be necessary...



New Member

Re: Updating ARP tables in routers/switches

We are simply upgrading this router (2600) to more robust model (3600 with FastEthernet). However, the IP addresses are going to be the same. I wanted to make sure that the hosts on the Ethernet segments (attached to this router) update their arp entries once the new router comes online. The IP addresses are going to stay the same when I upgrade this router. There two Ethernet segments on this router.

My concern is that some hosts will lose connectivity for an extended period of time. I'm afraid these host won't update their arp entries once the router is connected to the network. I thought gratuitous arp would solve my problem.

How do the other nodes on the Ethernet segments learn the new MAC address immediately?

Thanks for the advice,


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