Specifications
Enable Scrambled Data Coding
Configuring Serial Interfaces IC-109
You can use the following line speed settings: 2.4, 4.8, 9.6, 19.2, 38.4, 56, 64 kpbs, and an auto
setting.
The 64-kbps line speed cannot be used with back-to-back digital data service (DDS) lines. The
subrate line speeds are determined by the service provider.
Only the 56-kbps line speed is available in switched mode. Switched mode is the default on the
2-wire CSU/DSU and is enabled by the service-module 56k network-type interface configuration
command on the 4-wire CSU/DSU.
The auto linespeed setting enables the CSU/DSU to decipher current line speed from the sealing
current running on the network. Because back-to-back DDS lines do not have sealing current, use
the auto setting only when transmitting over telco DDS lines and using the line clock as the clock
source.
Use the no form of this command to enable a network line speed of 56 kbps, which is the default.
Enable Scrambled Data Coding
To prevent application data from replicating loopback codes when operating at 64-kbps on a 4-wire
CSU/DSU, use the following command for a serial interface in interface configuration mode:
Enable the scrambled configuration only in 64-kbps digital data service (DDS) mode. If the network
type is set to switched, the configuration is refused.
If you transmit scrambled bit codes, both CSU/DSUs must have this command configured for
successful communication.
To enable normal data transmission for the 4-wire, 56/64-kbps module, use one of the following
commands for a serial interface in interface configuration mode:
Change between Digital Data Service and Switched Dial-Up Modes
To transmit packets in Digital Data Service (DDS) mode or switched dial-up mode using the 4-wire,
56/64-kbps CSU/DSU module, use one of the following commands for a serial interface in interface
configuration mode:
Use the no form of these commands to transmit from a dedicated leased line in DDS mode. DDS is
enabled by default for the 4-wire CSU/DSU. Switched is enabled by default for the 2-wire
CSU/DSU.
Command Purpose
service-module 56k data-coding scrambled Scramble bit codes before transmission.
Command Purpose
service-module 56k data-coding normal
or
no service-module 56k data-coding
Specify normal data transmission.
Command Purpose
service-module 56k network-type dds
or
service-module 56k network-type switched
Transmit packets in switched dial-up mode or DDS
mode.