Specifying T3 Framing; Setting The Cable Length - Cisco PA-T3 Installation And Configuration Manual

Note
enable scrambling on the local port, you must do the same on the remote port.
See the "Interoperability Guidelines for PA-T3 Serial Port Adapter DSUs" section on page 2-5 for
information regarding DSU feature compatibilities.

Specifying T3 Framing

In interface configuration mode, specify T3 framing by entering the framing {c-bit | m13 | bypass}
configuration subcommand, as in the following example:
router(config-if)# framing c-bit
Use the no form of this command to return to the default, which is C-bit framing.
Note
must be set to the default, 0; and the DSU bandwidth must be set to the default, 44210.

Setting the Cable Length

In interface configuration mode, set the cable length (range of 0 to 450 feet), as in the following
example:
router(config-if)# cablelength 250
Use the no form of this command to return to the default, which is 10 feet.
Configuring Cyclic Redundancy Checks
The PA-T3 serial port adapter uses a 16-bit CRC by default; it also supports a 32-bit CRC.
CRC is an error-checking technique that uses a calculated numeric value to detect errors in
transmitted data. The sender of a data frame divides the bits in the frame message by a predetermined
number to calculate a remainder or frame check sequence (FCS). Before sending the frame, the
sender appends the FCS value to the message so that the frame contents are exactly divisible by the
predetermined number. The receiver divides the frame contents by the same predetermined number
that the sender used to calculate the FCS. If the result is not 0, the receiver assumes that a
transmission error occurred and sends a request to the sender to resend the frame.
Note
configuration mode and specify the slot and port address [and the interface port number for a VIP2]
of the PA-T3 serial port adapter), and then enter the command crc 32. Enter Ctrl-Z to exit from
configuration mode.
The local port configuration must match the remote port configuration. For example, if you
If you use the bypass option, scrambling must be set to the default, disabled; the DSU mode
To enable 32-bit CRC on an interface, follow Steps 1 and 2 of the preceding procedure (enter
Specifying T3 Framing
Configuring the PA-T3 Interfaces 8-13