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Chapter 5
Configuring the PA-4T+ Interfaces
When you have finished, press Ctrl-Z—hold down the Control key while you press Z—or enter end or
exit to exit configuration mode and return to the EXEC command interpreter prompt. Then write the new
configuration to NVRAM using the copy running-config startup-config command.
Cisco IOS Release 11.2(7a)P or later, or 11.1(10)CA or later loaded on your Cisco 7200 series router,
Note
Cisco 7000 series router, or Cisco 7500 series router with a VIP2-40(=) support nonstandard clock rates
(any value from 1200 to 8000000) on PA-4T+ interfaces.
Cisco IOS Release 12.0(3)T or later, or 12.0(1)XE or later support nonstandard clock rates on PA-4T+
interfaces installed in Cisco 7204VXR router and Cisco 7206VXR router.
Cisco IOS Release 11.3(6)NA or later loaded on your Cisco uBR7200 series router supports nonstandard
clock rates (any value from 1200 to 8000000) on PA-4T+ interfaces.
Set a nonstandard clock rate for an interface using the clock rate subcommand. Before you can assign
a nonstandard clock rate, you must use the interface serial command (followed by the interface address
of the interface) to select the interface to which you want to assign the nonstandard clock rate value.
In the following example, a nonstandard clock rate of 1234567 bps is specified:
Router(config-if)# clock rate 1234567
The preceding command example applies to all systems in which the PA-4T+ is supported. Use the
no clock rate command to remove the clock rate.
When you have finished, press Ctrl-Z—hold down the Control key while you press Z—or enter end or
exit to exit configuration mode and return to the EXEC command interpreter prompt.
Then write the new configuration to NVRAM using the copy running-config startup-config command.
The following example shows how to use the show running-config command to determine the exact
clock rate to which the nonstandard clock rate was rounded:
Router# show running-config
Building configuration...
...
!
interface Serial1/0 (interface Serial3/1/0 on a VIP2 or FlexWAN module)
no ip address
clockrate 1151526
!
...
In the preceding example, only the relevant output from the show running-config command is shown;
other information is omitted.
Inverting the Clock Signal
Systems that use long cables or cables that are not transmitting the TxC (clock) signal might experience
high error rates when operating at higher transmission speeds. If a PA-4T+ DCE port is reporting a high
number of error packets, a phase shift might be the problem. Inverting the clock might correct this shift.
When the PA-4T+ interface is a DTE, the invert-txc command inverts the TxC signal it receives from
the remote DCE. When the PA-4T+ interface is a DCE, this command inverts the clock signal to the
remote DTE port. Use the no invert-txc command to change the clock signal back to its original phase.
OL-3561-04
PA-4T+ Synchronous Serial Port Adapter Installation and Configuration
Configuring the Interfaces
5-13
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