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Static ARP entry not working, what am I missing?

So I have a router with a server connected. Also connected to that router is a switch, and on that switch is a Client. My problem is that if I change the ARP entry of the server to a different (incorrect) MAC, traffic still flows fine. Shouldn't an incorrect ARP entry in the router break the flow of traffic? The server and client are on different subnets.

The client is at 11.1.1.99/24, The server is at 12.1.1.2/24

My command was like arp ip.ip.ip.ip 0123.4567.89ab arpa

I must be missing something dumb here. What gives?

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level 1

Did you clear out the arp cache before setting the new arp entry?

level 2

And if that does not help, or just to explore, checking the actual CEF info could help. Show adjacency or show ip cef or something like that depending on the platform.

Quite possible that the router will not use some ranges of MAC addresses.

level 1
[deleted]
1 point · 8 months ago · edited 8 months ago

Would you mind posting the ARP address of the server and also the output of show ip arp I just configured this on an 1841 running Version 15.1(4)M12a and it worked as expected. What IOS are you running?

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