3com S7906E Manuel De Montage

 

2-1 

When configuring proxy ARP, go to these sections for information you are interested in: 

z 

z 

Enabling Proxy ARP 

z 

Displaying and Maintaining Proxy ARP 

If a host sends an ARP request for the MAC address of another host that actually resides on another 

network (but the sending host considers the requested host is on the same network) or that is isolated 

from the sending host at Layer 2, the device in between must be able to respond to the request with the 

MAC address of the receiving interface to allow Layer 3 communication between the two hosts. This is 

achieved by proxy ARP. Proxy ARP hides the physical details of the network. 

Proxy ARP involves common proxy ARP and local proxy ARP, which are described in the following 

sections. 

 

The term proxy ARP in the following sections of this chapter refers to common proxy ARP unless 

otherwise specified. 

 

A proxy ARP enabled device allows hosts that reside on different subnets to communicate. 

As shown in 

, Router connects to two subnets through Vlan-interface1 and Vlan-interface2. 

The IP addresses of the two interfaces are 192.168.10.99/24 and 192.168.20.99/24. Host A and Host B 

have the same prefix 192.168.0.0 assigned and connect to Vlan-interface1 and Vlan-interface2, 

respectively.. 

Figure 2-1 Application environment of proxy ARP 

   

 

 

Because Host A considers that Host B is on the same network, it directly sends an ARP request for the 

MAC address of Host B. Host B, however, cannot receive this request because it locates in a different 

broadcast domain.