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New Member

3750G won't "age out" old arp table entries

WS-C3750G-24TS running

12.2(20)SE4, RELEASE SOFTWARE (fc1).

sho mac-address-table aging-time

Vlan Aging Time

---- ----------

253 300

252 300

254 300

255 300

1 300

251 300


The aging is not working. I can failover some devices I have and the mac-address of the old device associated the the IP never ages out. "Clear arp" makes the standby unit respond to pings and connectivity to the standby unit is 100% after the "clear arp".

Showing the arp cache, I can see the IP associated with the old mac-address and the "age" keeps increasing, not decreasing with the old mac-address.

It also doesn't matter if the Primary unit has been rebooted, switch keeps the old mac-address associated the Primary unit.


New Member

Re: 3750G won't "age out" old arp table entries



Re: 3750G won't "age out" old arp table entries

I think permanent entry should have been made into the arp cache using the "arp ip-address hardware-address type" command.

To remove this arp entry, you can try "clear arp-cache".This will delete all dynamic entries from the ARP table.

for more details, refer the following page:

New Member

Re: 3750G won't "age out" old arp table entries

why would I want to make a perm. apr entry? I need the arp cache to "age-out" in 5 mins like my sho command indicates.

The aging-time for my arp table is 5 mins. I need the old mac-address associated with the IP to "age-out" so my new mac-address can be associated with the same IP.