Configuring 4-Bit Cyclic Redundancy Check; Replacing Port Adapter Cables - Cisco 7000 Hardware Installation And Maintenance

Installing and Configuring Processor Modules
The default for all serial interfaces is for 16-bit CRC. To enable 32-bit CRC on an interface, specify
the slot and port address of the interface followed by the command crc32. In the example that
follows, the top serial port on an FSIP in interface processor slot 3 is configured for 32-bit CRC:
To disable CRC-32 and return to the default CRC-16 setting, specify the slot and port address and
use the no crc32 command.
For a brief overview of CRCs refer to the section "Cyclic Redundancy Checks (CRCs)" in the
chapter "Preparing for Installation." For complete command descriptions and instructions refer to
the related software configuration and command reference documentation.

Configuring 4-Bit Cyclic Redundancy Check

The E1-G.703/G.704 interface supports 4-bit CRC in framed mode only. CRC-4 is not enabled by
default.
To enable CRC-4 on the E1-G.703/G.704 interface, specify the slot and port address of the interface
followed by the command crc4. In the example that follows, the top port on an FSIP in IP slot 3 is
configured for CRC:
To disable CRC-4 and return to the default of no CRC error checking, specify the slot and port
address and use the no crc4 command. For complete command descriptions and instructions, refer
to the related software documentation.

Replacing Port Adapter Cables

The port adapter cable connected to each port determines the electrical interface type and mode of
the port. The default mode of the ports is DCE, which allows you to perform a loopback test on any
port without having to attach a port adapter cable. Although DCE is the default, there is no default
clock rate set on the interfaces. When there is no cable attached to a port, the software actually
identifies the port as Universal, Cable Unattached rather than either a DTE or DCE interface.
5-208 Cisco 7000 Hardware Installation and Maintenance
7000# configure terminal
interface serial 3/0
crc32
^z
Router# configure terminal
interface serial 3/0
crc4
^z