ADTRAN Express L1.5, User Manual

Page: 48 / 145

Chapter 3: Terminal Menu Operation and Structure
32 Express L768/L1.5 User Manual 61202192L1-1
IP/Proxy ARP
Write security: 4; Read security: 5
This feature allows the network portion of a group of addresses to be shared
among several physical network segments. The ARP protocol itself provides a
way for devices to create a mapping between physical (i.e., Ethernet) address-
es 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 cor-
rectly 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 L768/L1.5 will answer
the request with its own hardware address. If set to
No , the Express L768/L1.5
will only respond to ARP requests received for its own IP address.