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Channel Associated Signaling CAS

This topic describes the commands required to configure a Channel Associated Signaling (CAS) interface.

Basic T1/E1 Controller Configuration
	CMERouter(config-control)#
	linecode {ami | b8zs}
	• Configures the linecode for a T1 line
	CMERouter(config-control)#
	linecode {ami | hdb3}
	• Configures the linecode for a E1 line

Use the linecode command to identify the physical layer signaling method to satisfy the ones density requirement on the digital facility of the provider. Without a sufficient number of ones in the digital bit stream, the switches and multiplexers in a WAN can lose their synchronization for transmitting signals. The table shows linecode command.

linecode Command

Command	Description
ami	Alternate mark inversion. Used for T1 configurations.
b8zs	Binary 8-zero substitution. Use for T1 PRI configurations.
hdb3	High density binary 3. Use for E1 PRI configurations.

Binary 8-zero substitution (B8ZS) accommodates the ones density requirements for T1 carrier facilities using special binary signals encoded over the digital transmission link. It allows 64 kbps (clear channel) for ISDN channels.

Settings for these two Cisco IOS software controller commands on the router must match the framing and line-code types used at the T1/E1 WAN central office (CO) switch of the provider.

T1 configurations typically require framing esf and linecode b8zs. E1 configurations typically require linecode hdb3.

Basic T1/E1 Controller Configuration
	CMERouter(config-control)#
	framing {sf | esf}
	• Configures the framing for a T1 line
	CMERouter(config-control)#
	framing {crc4 | no-crc4 | australia}
	• Configures the framing for a E1 line

Use the framing controller configuration command to select the frame type used by the PRI service provider. The table shows framing commands you can use.

framing Command

Command	Description
sf	Super Frame. Use for some older T1 configurations.
esf	Extended Super Frame. Use for T1 PRI configurations.
crc4 or no-crc4	Cyclic redundancy check 4. Use for E1 PRI configurations.

Note Esf and crc4 are most common in new T1s or E1s

Basic T1/E1 Controller Configuration
	CMERouter(config-control)#
	dsO-group ds0-group-no timeslots timeslot-list type {e&m-delay-dial | e&m-fgd | e&m-immediate-start | e&m-wink-start | ext-sig | fgd-eana | fxo-ground-start | fxo-loop-start | fxs-ground-start | fxs-loop-start}
	• Creates the voice ports of the T1 or E1 and the signaling that is used
	CMERouter(config-control)#
	clock source {line | internal}
	• Sets the source of the clocking

You must create a digital voice port in the T1 or E1 controller to make the digital voice port available for specific voice port configuration parameters. You must also assign timeslots and signaling to the logical voice port through configuration. The first step is to create the T1 or E1 digital voice port with the ds0-group dsO-group-no timeslots timeslot-list type signal-type command.

The ds0-group part of the command automatically creates a logical voice port that is numbered as dsO-group-no. The dSO-group-no parameter identifies the DS0 group (number from 0 to 23 for T1 and from 0 to 30 for E1). This group number is used as part of the logical voice port numbering scheme.

The timeslots part of the command allows the user to specify which timeslots are parts of the DS0 group. The timeslot-list parameter is a single time-slot number, a single range of numbers, or multiple ranges of numbers separated by commas.

The type part of the command defines the emulated analog signaling method that the router uses to connect to the PBX or PSTN. The type depends on whether the interface is T1 or E1.

To delete a DS0 group, you must first shut down the logical voice port. When the port is in shutdown state, you can remove the DS0 group from the T1 or E1 controller with the no ds0-group dsO-group-no command.

Use the clock source {line | internal} command to configure the T1 and E1 clock source on Cisco routers.

CMERouter(config)#controller T1 1/0 CMERouter(config-controller)#linecode b8zs CMERouter(config-controller)#framing esf

CMERouter(config-controller)#ds0-group 1 timeslots 1-24 type fxo-groundstart CMERouter(config-controller)#clock source line

CMERouter(config)#controller T1 1/0 CMERouter(config-controller)#linecode b8zs CMERouter(config-controller)#framing esf

CMERouter(config-controller)#ds0-group 1 timeslots 1-24 type fxo-groundstart CMERouter(config-controller)#clock source line

CMERouter(config)#controller E1 1/0 CMERouter(config-controller)#linecode hdb3 CMERouter(config-controller)#framing crc4

CMERouter(config-controller)#ds0-group 1 timeslots 1-15 type e&m-wink-start CMERouter(config-controller)#clock source line

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