
Configuring Dial Services
4-10 114062 Rev. B
An alternative to configuring adjacent hosts is to configure IP unnumbered
interfaces. An unnumbered interface is a point-to-point connection that does not
use an IP address. Instead, you configure the address to be 0.0.0.0. You can use
unnumbered interfaces to advertise routing information across the network. Since
all traffic over an unnumbered interface uses broadcast addressing at the data link
layer, you do not need adjacent hosts.
Adjacent hosts and unnumbered interfaces are features of the router’s IP interface.
To configure these features, refer to Configuring IP Services.
ISDN Services
A router with built-in ISDN capability is a TE1 device, which is an
ISDN-compatible device. This means that the router provides the S/T interface,
which defines the boundary between the user and the network. (The ARN also
provides the U interface, which includes an integral NT1 interface.) The NT1
interface defines the point at which the service provider’s wires terminate at your
site.
For BRI service, the S/T interface follows the standards outlined in ITU-T
recommendation I.430, the physical layer protocol that defines the S/T interface.
For PRI service, the interface follows ITU-T recommendation I.431.
You have an S interface only if an NT2 device is present. An NT2 is a switch at
your site that connects your TE1 and TE2 equipment to the network.
Figure
4-6 shows the router in a sample ISDN network.
Figure 4-6. Router in an ISDN Network
The following sections explain ISDN operation on your router.
router
Digital line
S/T
U
TE1 NT1
ISDN
DS0012A
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