How can a Juniper Router update its arp table?

Question

I know the ARP table is cached data.

On Juniper, we can use show arp to query the arp table:

admin@juniper> show arp | match "16.23.43.75"                               
ac:1f:6b:90:d1:ca 16.23.43.75   16.23.43.75             ae16.83             
    none  

But the arp is not a real-time table, you know.

If we shutdown the 16.23.43.75 server, we can still query out the 16.23.43.75 record.

Is there a way to refresh the arp table in the case do not affect other routing?

Answer 1

You can clear the arp table for the interface by issuing clear arp interface ae16.83. This will remove all entries for the interface (which means ARP learning has do be done for all hosts on the interface). If you want to remove one host you can try to use clear arp hostname [IP-Address] and this works sometimes as well. Normally it is not necessary to do this by hand as the entry expires anyway after a while.