Hardware manual

invert txclock
IR-124
Cisco IOS Interface Command Reference
invert txclock
Use the invert txclock interface configuration command to invert the transmit clock signal. Delays
between the SCTE clock and data transmission indicate that the transmit clock signal might not be
appropriate for the interface rate and length of cable being used. Different ends of the wire can have
variances that differ slightly.The invert txclock command compensates for these variances. This
command replaces the invert-transmit-clock command.
This command applies only to Cisco 7200 series and Cisco 7500 series routers. To return to the
transmit clock signal to its initial state, use the no form of this command.
invert txclock
no invert txclock
Syntax Description
This command has no arguments or keywords.
Default
Transmit clock signal is not inverted.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
This command was modified in Cisco IOS Release 11.3 to change the command from
invert-transmit-clock to invert txclock.
Systems that use long cables or cables that are not transmitting the TxC signal (transmit echoed
clock line, also known as TXCE or SCTE clock) can experience high error rates when operating at
the higher transmission speeds. For example, if a PA-8T synchronous serial port adapter is reporting
a high number of error packets, a phase shift might be the problem. Inverting the clock might correct
this shift.
When a PA-8T or PA-4T+ port adapter interface is DTE, the invert txclock command inverts the
TxC signal it received from the remote DCE. When the PA-8T or PA-4T+ port adapter interface is
DCE, this command changes the signal back to its original phase.
Example
The following example inverts the clock signal on serial interface 3/0:
interface serial 3/0
invert txclock