Clear ARP Command Question

[PolarPanda]

Hi there,

           I have some virtual servers not being used. I checked with server team and they said they're powered off. Sometimes I can see the static ips shows in arp table in the switch, but sometimes not. I want to permanently delete those for future troubleshooting purpose. I do have following questions:

1. Why do servers keep sending arp request?

2. Why do I see them sometimes in arp table, but not all the time?

3. clear ip arp x.x.x.x force-delete will solve the problem? If not, what's the reason?

            Thank you.

[Jaderson Pessoa]

@PolarPanda hello

Hello

These machine are virtual or physical?

automatic all mac address in the table are flushed every 5min.

"clear ip arp x.x.x.x force-delete" this command just will force the flush at this moment and if the server connec his NIC again it will be showed in mac address table.

look here for more detail: https://www.cisco.com/c/m/en_us/techdoc/dc/reference/cli/nxos/commands/l3/clear-ip-arp.html

[PolarPanda]

Thank you. I think some of them might be physical. Is there any different between virtual and physical? So sounds like we have to disconnect physically and make sure nic not active, otherwise no way to delete from switch side? If cannot delete, can I block them to show on arp table?

[balaji.bandi]

Not sure what device you have here, what Switch model.

You can decrease arp time out like 180 Seconds, it may have set up default config arp time out. IOS has reasonable, Nexus has a very high time default arp to time out.

can you post some sample ARP information to understand better?