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Configuring the FSIP
Configuring E1-G.703/G.704 Loopback
The E1-G.703/G.704 interface supports the same local loopback test as the other (data
communications) FSIP interfaces. Loopback functions enable you to check the integrity of the
physical data path between the FSIP and the E1 port adapter with the loopback command. The
no loopback command disables all loopback tests on the interface.
You do not have to configure a clock signal on the interface before performing a loopback test
because the E1-G.703/G.704 interface uses a default clock rate of 2.048 Mbps.
The loopback command tests the path between the FSIP and the interface port (without leaving the
FSIP and port adapter). On the E1 port adapter, the loopback signal follows this path regardless of
whether or not a cable is attached to the port.
Figure 25 shows the path of the loopback function.
Figure 25
FSIP
Replacing Port Adapter Cables and Changing Interface Modes
The port adapter cable connected to each port determines the electrical interface type and mode of
the port. The default mode of the ports is DCE, which allows you to perform a loopback test on any
port without having to attach a port adapter cable. Although DCE is the default, there is no default
clock rate set on the interfaces. When there is no cable attached to a port, the software actually
identifies the port as Universal, Cable Unattached rather than either a DTE or DCE interface.
Following is an example of the show controller cxbus command, which shows the first serial port
on an FSIP in interface processor slot 0 (0/0) that has an EIA/TIA-232 DTE cable attached, and a
second serial port (0/1) with no cable attached:
To change the electrical interface type or mode of a port online, you must replace the serial adapter
cable and use software commands to restart the interface and, if necessary, reconfigure the port for
the new interface.
44 Fast Serial Interface Processor (FSIP) Installation and Configuration
Loopback Path for FSIP E1-G.703/G.704
Loopback
EI-G.703/G.704
port adapter
Router# show controller cxbus
(additional displayed text omitted from this example)
FSIP 0, hardware version 3, microcode version 1.0
Interface 16- Serial0/0, electrical interface is RS-232 DTE
31 buffer RX queue threshold, 101 buffer TX queue limit, buffer size 1520
Transmitter delay is 0 microseconds
Interface 17- Serial0/1, electrical interface is Universal (cable unattached)
31 buffer RX queue threshold, 101 buffer TX queue limit, buffer size 1520
(additional displayed text omitted from this example)
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