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jimmycherFlag for United States of America

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Clearing the ARP table on a L2 switch when installing a new device

We have a L2 switch in a remote location; it is connected to HQ by a metro-ethernet.   We replaced a server on Fa0/5, keeping the same IP address.   We could not PING the new device, from either direction.  I was unable to find the ARP entry in the L2 switch, but I did clear it in the HQ router (which was attached to the metro-ethernet).  Once I did that, every thing worked fine.   My question is:  why did I have to manually clear the ARP entry?  Why didn't the PING from either direction force-clear it?   I know I've replaced servers in the past, without having to manually clear ARP.  Did the metro-ethernet complicate things?
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Andrej Pirman
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Ken Boone
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Lasby, Ken,    

Thanks for prompt and enlightening responses.  

We only have one active network at the remote site, but I put the SVI on a seperate "mgmt" subnetwork.    I assume that is best practise, but if it makes things simpler, should I put the SVI on the same subnet as my active hosts?

I didn't get the chance to open an unused switch port, but moving the device to a clean port would have certainly cleared the issue as well, yes?

jc
Given that the mgmt subnet is on a different subnet simply means that the ARP entries in the switch are irrelevant.  That switch will only see ARP entries on the mgmt network.  

Best practice would be to do what you are doing.  It won't solve anything by putting it on the same network.