Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Isolate PPPoE IP address from LAN port


I have a 2800 router, with one LAN port(G0/1) set to a local IP address (say and is connected to a LAN switch, and another LAN port(G0/0) is used for PPPoE DSL modem (fixed IP, say connection. The problem is that if I connect a PC, whose IP address is in the same subnet of the PPPoE's, say, to the same LAN switch with G0/1, while I ping from PC, G0/1 responses the ARP request that is him. Is there any way to prevent G0/1 from recognizing himself as

Thanks much.


Re: Isolate PPPoE IP address from LAN port

this is proxy ARP functionality . 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. Proxy ARP is enabled by default.

If you want disabel this functionality follows the following commands and set the default gateway in your PC.

Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)# interface giga0/1

Router(config-if)# no ip proxy-arp

Router(config-if)# ^Z