3850 arp table entry

[swordfish7769]

I am working with a 3850 as my L3 switch.  If I do a sho ip arp on that switch I have an entry in there that needs to be deleted.  If I do a clear arp-cache or clear ip arp the entry still remains.  I have tried the clear command several times over the last 10 days.  The entry I need deleted is pointing to a mac address that is no longer being used and need the IP to get the correct mac for the new router interface that has that IP.  What am I missing?

Thank you!

[balaji.bandi · Accepted solution]

check is there any static MAC entry for that. when you clear the MAC address table,

post before clearing mac table and post after clearning mac table to understand.

exmaple if any ARP manuall, you see as below :

show run | in arp

arp x.x.x.x yyy.yyyy.yyyy ARPA alias

#show ip arp x.x.x.x
Protocol Address Age (min) Hardware Addr Type Interface
Internet x.x.x.x - yyyy.yyyy.yyyy ARPA

[swordfish7769]

That was easy enough.  Totally missed that in the config.  Thank you for the quick and accurate reply!

[Georg Pauwen]

Hello,

can you post a screenshot of the entry ?

[Richard Burts]

The behavior described is not the expected behavior. If you issue the clear command but the entry remains in the arp table it suggests that somehow it is relearning the entry. I have a few thoughts about this:

- what is the age shown in the entry? does the age increase to a point and then start over again?

- is it possible that there is another device in the network using that IP address? and that you are learning the entry from that device?

- is it possible that the entry is a static entry and not learned dynamically?

- the output of show run would help us determine if the config places that entry in the table.

- if all else fails run debug for arp, clear the arp table, post the debug output