Hardware manual

invert data
IR-120
Cisco IOS Interface Command Reference
invert data
To invert the data stream, use the invert data interface configuration command. This command
applies only to the Cisco 7000 series routers with the RSP7000 and RSP7000CI, Cisco 7200 series
routers, and Cisco 7500 series routers. Use the no form of this command to disable inverting the data
stream.
invert data
no invert data
Syntax Description
This command has no arguments or keywords.
Default
Data is not inverted.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.1 CA and Release 11.2 P.
T1 Line without B8ZS Encoding
If the interface on the PA-8T and PA-4T+ synchronous serial port adapters and the PA-T3 and
PA-2T3 synchronous serial port adapters is used to drive a dedicated T1 line that does not have B8ZS
encoding (a method to avoid 15 zeros), the data stream must be inverted (both TXD and RXD) either
in the connecting CSU/DSU or the interface.
Inverting is a method of avoiding excessive zeroes that is superseded by the use of B8ZS encryption.
This option could be needed for use with legacy equipment that supports this option. By inverting
the HDLC data stream, the HDLC zero insertion algorithm becomes a ones insertion algorithm that
satisfies the T1 requirements. Be careful not to invert data both on the interface and on the CSU/DSU
as two data inversions will cancel each other out.
AMI Line Coding
If the interface on the CT3IP uses AMI line coding, you must also invert the data on the T1 channel.
For more information, see the t1 linecode controller configuration command.
Example
The following example inverts data on serial interface 3/1/0:
interface serial 3/1/0
invert data