question about no ip proxy-arp command

[mgtang]

I found that my arp table is very big and it consume about 3% CPU of my 1721. Will "no ip proxy-arp" command decrease my arp table? What did "ip proxy-arp" do? I know it is enabled by default, if I turn it off, will it be affect my Internet and Intranet connection? Any idea will be appreciated. Thanks!

Router Info: Cisco 1721, 96M RAM, WIC-2T(nat inside, f0 also), WIC-1Enet (nat outside).

[rwiesmann]

Hi

Proxy ARP helps Host with no knowledge routing determine the addresses of hosts on other subnets.

For example, if the router receives an ARP request for a host that is not on the same interface as the ARP request sender, and if the router has all of its routes to that host through other interfaces, then it generates a proxy ARP reply packet giving its own local data-link address.

The host that sent the ARP request then sends its packets to the router, which forwards them to the intended host.

As you mentioned Proxy ARP is enabled by default.

So if you have set the default gateway on the hosts towards the router you can disable the ip proxy-arp.

Hope that helps

Roger

[mgtang]

Thanks Roger!