Information Technology Reference
In-Depth Information
Table15-1 Serial Lines: show interfaces serial Status Line Conditions (continued)
Status Line
Condition
Possible Problem
Solution
Serial x is
up, line
protocol is
down (DTE
mode)
(continued)
Caution: Because debugging output is
assigned high priority in the CPU process, it
can render the system unusable. For this
reason, use debug commands only to
troubleshoot specific problems or during
troubleshooting sessions with Cisco technical
support staff. Moreover, it is best to use debug
commands during periods of lower network
traffic and fewer users. Debugging during
these periods decreases the likelihood that
increased debug command processing
overhead will affect system use.
If the line protocol does not come up in
local loopback mode, and if the output of
the debug serial interface exec command
shows that the keepalive counter is not
incrementing, a router hardware problem
is likely. Swap router interface hardware.
5.
If the line protocol comes up and the
keepalive counter increments, the
problem is not in the local router.
Troubleshoot the serial line, as described
in the sections “Troubleshooting Clocking
Problems” and “CSU and DSU Loopback
Tests,” later in this chapter.
6.
If you suspect faulty router hardware,
change the serial line to an unused port. If
the connection comes up, the previously
connected interface has a problem.
7.
Serial x is
up, line
protocol is
down (DCE 6
mode)
The clockrate
interface
configuration
command is missing.
The DTE device does
not support or is not
set up for SCTE mode
(terminal timing).
The remote CSU or
DSU has failed.
1. Add the clockrate interface configuration
command on the serial interface.
Syntax:
clock rate bps
Syntax Description:
bps —Desired clock rate in bits per
second: 1200, 2400, 4800, 9600, 19200,
38400, 56000, 64000, 72000, 125000,
148000, 250000, 500000, 800000,
1000000, 1300000, 2000000, 4000000, or
8000000.
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