is there a maximum number of ARP entries per physical interface?

[rkhanso]

Is there a maximum number of ARP entries per physical interface?  I don't want to set a maximum number, I'm wondering what the maximum number supported is....specifically on a Cisco 2921.

The reason...we have a competitor router installed now, which has a limit of 256 entries. We have 280+ and are seeing packet drops, messages in the log stating that we've hit a maximum number:   2000.02.10 19:45:36 ARP.REQUEST Packet not enqueued on eth 0/2: Current Pkt Count Exceeded

Before putting a Cisco in, I wanted to confirm it could handle the number of LAN devices in ARP.

Searching the Internet, I've only found statements that there are limits, which are platform specific.  But, I can't find anything stating what those limits are.

Thanks.

[Peter Paluch]

Hi,

I do not believe there is any specific limit for the count of ARP entries in a Cisco router. Certainly, the amount of ARP entries is not limited on a per-interface basis. I even tend to believe that the number of ARP entries it not limited at all by the IOS - a couple of years ago, a thread was running here on Cisco Support Community about a router rebooting every now and then. It eventually turned out that the default route on that router was configured simply as ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 which caused the router to ARP for each and every destination IP address of packets going to internet, storing thousands of ARP entries, eventually exhausting its memory and reloading. This would not have happened if the number of ARP entries was limited.

Best regards,
Peter

[Jon Marshall]

Hi Peter

If you get the chance can you nip over to this thread and see what you think ?

https://supportforums.cisco.com/discussion/12430721/vtp-explanation-changed-modes-vtp-server-vtp-transparent-caused-outage

Jon