Compatible Systems 5.4 - Manual (Page 55)

Chapter 2 - IP Routing & Bridging 49
• If set to On, then any ARP request received on this interface whose IP
network portion matches the network portion of the IP address on
another interface of the device (as found by applying the Subnet Mask
for that interface to the IP address for that interface) will be answered by
the device with the physical address of this interface.
• If set to Off, then the device will only respond to ARP requests received
for its own IP interface address. This is the default setting.
v Note: Using Proxy ARP requires an in depth understanding of the work-
ings of the IP protocol, along with careful manipulation of the IP subnet
masks for the interfaces on a device. A more straightforward method of
achieving similar results is to use Bridging (if available in your device).
UDP Forwarding Agents (Relays)
The “Relays” button brings up a configuration dialog box that can be used to
turn on a relay agent in the device for UDP (User Datagram Protocol) broad-
cast packets.
UDP Forwarding Agents Dialog Box
Normally, a device will not forward UDP broadcast packets. However, many
network applications use UDP broadcasts to configure addresses, hostnames,
and other information. If hosts attempting to use these protocols are not on the
same network segment as the servers which provide the information, the hosts
will not receive a response unless a relay agent has been enabled in a device.
When a relay agent is enabled for an interface, the device is instructed to
forward specific protocols received on that interface to a Server IP Address.
The server does not need to reside on a network segment directly attached to
the device.