ADTRAN Express 4100, User Manual

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Chapter 3. Terminal Menu Operation and Structure
61200176L2-1 Express 4100/4110 User Manual 3-21
IP/Proxy ARP
Write security: 4; Read security: 5
This feature allows the network portion of a group of addresses to be
shared between several physical network segments. The ARP protocol
itself provides a way for devices to create a mapping between physical
(i.e., Ethernet) addresses and logical IP addresses. Proxy ARP makes use
of this mapping feature by instructing a router to answer ARP requests as
a “proxy” for the IP addresses behind one of its ports. The device which
sent the ARP request will then correctly assume that it can reach the
requested IP address by sending packets to the physical address that was
returned to it. This technique effectively hides the fact that a network has
been (further) subnetted. If this option is set to Yes (def), when an ARP
request is received on the Ethernet port the address is looked up in the IP
routing table. If the forwarding port is not on the Ethernet port and the
route is not the default route, the Express 4100/4110 will answer the
request with its own hardware address. If set to No, the Express 4100/
4110 will only respond to ARP requests received for its own IP address.