small, the configuration process can be laborious. A better solution is a dynamic protocol called
Inverse ARP.
that maps the Layer 3 and Layer 2 addresses is still found. Inverse ARP is basic; after the VC
is up, each DTE announces its network layer address to the DTE on the other end of the VC.
(Inverse ARP is enabled by default at IOS 11.2 and beyond, unless point-to-point subinterfaces
are used.) Table 8-21 summarizes what would occur in the network in Figure 8-16.
commands are needed. All the necessary mapping information is learned dynamically.
default for multipoint subinterfaces. However, Inverse ARP is not enabled on point-to-point
subinterfaces because point-to-point subinterfaces behave like a true point-to-point line in
regard to routing; if the packet needs to be sent out a point-to-point subinterface, then there is
only one possible next router and only one DLCI in use. So, Inverse ARP is not needed with
point-to-point subinterfaces.
Router
Header of
I-ARP Frame
When Sent
Router
Header of
I-ARP Frame
When
Received
Inverse ARP