Chapter 15: 56/64-kbps Switched and Digital Data Services (DDS) Interface

Enable

Scrambled Data

Coding

In interface configuration mode, prevent application data from repli cating loopback codes when operating at 64-kbps on a 4-wire CSU/ DSU by scrambling bit codes before transmission:

service-module 56k data-coding scrambled

Enable the scrambled configuration only in 64-kbps digital data ser- vice (DDS) mode. If the network type is set to switched, the configu- ration is refused.

If you transmit scrambled bit codes, both CSU/DSUs must have this command configured for successful communication.

In interface configuration mode, enable normal data transmission fo the 4-wire 56/64-kbps module, which is the default:

service-module 56k data-coding normal

or

no service-module 56k data-coding

Change between DDS and Switched Dial-Up Modes

In interface configuration mode, transmit packets in switched dial-up mode or DDS mode using the 4-wire 56/64-kbps CSU/DSU module:

service-module 56k network-type dds

or

service-module 56k network-type switched

Do not use any form of these commands to transmit from a dedicated leased line in DDS mode. DDS is enabled by default for the 4-wir CSU/DSU. Switched mode is enabled by default for the 2-wire CSU/ DSU.

In switched mode, you need additional dialer configuration commands to configure dial-out numbers. Before you enable the service- module 56k network-type switched command, both CSU/ DSUs must use a clock source coming from the line and the clock rate must be configured to auto or 56k kbps. If the clock rate is not set cor- rectly, this command will not be accepted.

The 2-wire and 4-wire 56/64-kbps CSU/DSU modules use V.25 bis dial commands to interface with the router. Therefore, the interfac must be configured using the dialer in-bandcommand. DTR dial is not supported.

Warning: Any loopbacks in progress are terminated when switching between modes.

August 1997

Page 15-3

2524UM

 

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AIS AI2524 user manual Enable Scrambled Data Coding, Change between DDS and Switched Dial-Up Modes