ADC Campus-REX2 RS - Manual (Page 142)

Chapter 8 - Internetworking and Management Overview
130 Campus-REX2 RS Interface Card User Manual
which is for the HDSL connection. Note that the IP Line address is different
from the LAN addresses. When connecting two Campus-REX2 units
point-to-point through HDSL, the IP Line addresses are completely isolated
and hidden from the rest of the network. You can assign any subnet to the
Line IP addresses.
When routing, data travels one hop at a time. The figure below shows
destination and next hop IP addresses. The destination address indicates the
network and subnetwork of the next hop. The next hop is the next-stop IP
address node. The default gateway is the upstream routing device. Use this
example to help you determine/record static IP routing addresses.