What happens when the ARP table is full?

[x]

Hello Guys,

What happens when the ARP table is full? Does the firewall clear old entries?

Just trying to figure out if what's causing an issue with our wireless is due to the ARP table being full. 

Thanks, Chris

[HULK]

Hello X,

As per the design of PAN firewall, ARP Entries Stay Cached for 30 Minutes.

Stopping Unwanted Entries from Populating the ARP Table

ARP Entries Stay Cached for 30 Minutes

Thanks

[HULK]

Please find below the max capacity across all PAN platforms.

Example:

:

You can verify through CLI command:

admin@31-PA-3020> show system state | match arp

cfg.general.max-arp: 1500  >>>>>>>>>>>>>>>>>

Thanks

[x]

Thanks Hulk. I've got a small device PA-200 that I'm testing so the limit is 500 per subnet it seems. Now, if the table is full and they are all entries within 30 minutes, what happens to the next device that tries to connect? Will the firewall clear the oldest entry for the new one or it will just won't accept the ARP for the new device?

[HULK · Accepted solution]

Hello X,

If the PA-200 reaches it's max capacity ( 500 per device), it would not accept any new ARP request. The firewall will not clear it's table before 30 minutes. Hence, as a result the new enty should be dropped.

Thanks