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Software Configuration Guide for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
OL-1957-03
Chapter 3
Configuring with the Command-Line Interface
Configuring Asynchronous/Synchronous Serial Network Modules or WAN Interface Cards
Step 11
Router(config-if)# clockrate 7200
To use a port in DCE mode, connect a DCE cable
and set the internal transmit clock signal (TXC)
speed in bits per second. See
Table 3-2
through
Table 3-5
for a list of clock rate settings for your
specific interface. (For ports used in DTE mode,
the router automatically uses the external timing
signal.)
Step 12
Router(config-if)#
dce-terminal-timing-enable
When a port is operating in DCE mode, the default
operation is for the DCE to send serial clock
transmit (SCT) and serial clock receive (SCR)
clock signals to the DTE, and for the DTE to
return a serial clock transmit external (SCTE)
signal to the DCE.
If the DTE does not return SCTE, enter this
command to configure the DCE port to use its own
clock signal.
Step 13
Router(config-if)# invert-txc
Routers that use long cables might experience
high error rates when operating at higher
transmission speeds, because the clock and data
signals can shift out of phase.
If a DCE port is reporting a high number of error
packets, inverting the clock using this command
can often correct the shift.
Step 14
Router(config-if)# nrzi-encoding
All serial interfaces support both nonreturn to zero
(NRZ) and nonreturn to zero inverted (NRZI)
formats. NRZ is the default; NRZI is commonly
used with EIA/TIA-232 connections in IBM
environments. To enable NRZI encoding on an
interface, enter this command.
Step 15
Router(config-if)# exit
Exit back to global configuration mode.
Repeat Step 4 through Step 14 if your router has
more that one serial interface that you need to
configure.
Step 16
Router(config)# Ctrl-z
Router#
When you finish configuring interface, return to
enable mode.
Command
Purpose
