Specifications

Configure a Channelized T3 Interface Processor
IC-86
Cisco IOS Interface Configuration Guide
Note Although you can specify a cable length from 0 to 655 feet, the hardware only recognizes the
following ranges: 0 to 133, 134 to 266, 267 to 399, 400 to 533, and 534 to 655. For example, entering
150 feet uses the 134 to 266 range. If you later change the cable length to 200 feet, there is no change
because 200 is within the 134 to 266 range. However, if you change the cable length to 399, the 267
to 399 range is used. The actual number you enter is stored in the configuration file.
Loopback T1 Channels
You can perform the following types of loopbacks on a T1 channel:
• Local—Loops the router output data back toward the router at the T1 framer and sends an AIS
signal out toward the network (see Figure 12).
• Network line—Loops the data back toward the network before the T1 framer and automatically
sets a local loopback (see Figure 13).
• Network payload—Loops just the payload data back toward the network at the T1 framer and
automatically sets a local loopback (see Figure 14).
• Remote line inband—Sends a repeating 5-bit inband pattern (00001) to the remote end
requesting that it enter into a network line loopback (see Figure 15).
To enable loopbacks on a T1 channel, use the first command in global configuration mode, followed
by any one of the following commands:
Note The port adapter and port numbers for the CT3IP are 0.
Figure 12 shows an example of a local loopback in which the loopback occurs in the T1 framer.
Command Purpose
interface serial slot/port-adapter/port:t1-channel Select the T1 channel (values are 1 to 28) on the CT3IP
and enter interface configuration mode.
loopback local Enable the local loopback on the T1 channel.
loopback network line Enable the network line loopback on the T1 channel.
loopback network payload Enable the network payload loopback on the T1
channel.
loopback remote line inband Enable the remote line inband loopback on the T1
channel.