Access Server Administrators’ Reference Guide

C • Technical Reference

 

 

Configuring Non-Facility Associated Signaling (NFAS)

NFAS allows PRIs to be fully utilized by increasing the number of data channels. Now PRIs can have 24 B- channels for data rather than the traditional 23 B-channels for data and a D-channel for signaling.

The telephone company can configure a group of PRIs to share a single D-channel. In that group of PRIs, one PRI will contain a D-channel and 23 B-channels. The other PRIs in the NFAS group will have 24 B-channels. The request for an in-bound call now contains an interface identifier that indicates for which PRI in the NFAS group the call is destined.

The NFAS group cannot span multiple remote access server units. Each RAS must have at least one PRI con- figured with a D-channel.

Configuring NFAS

NFAS only impacts the configuration of the signaling settings. The line interface settings do not change with an NFAS implementation.

Example 1

The RAS hosts 2 NFAS groups, each containing 2 PRIs. WAN 1 will have the PRI with the D channel. WAN 2 will have the second PRI for that group. WANs 3 and 4 will contain the second NFAS group.

Signal setting for each WAN port

 

WAN 1

WAN 2

WAN 3

WAN 4

 

 

 

 

 

Switch Type

att(2)**

nfsSlave(7)

att(2)**

nfsSlave(7)

 

 

 

 

 

Interface ID

0

1

0

1

 

 

 

 

 

Primary WAN

1

1

3

3

 

 

 

 

 

**The switch type for the primary WAN is set to the flavor of ISDN the switch is configured for. This does not change for an NFAS implementation.

*The Interface ID must match what the central office has designated. The PRI with the D-channel must be configure with an ID of 0. Typically, the other PRIs have interface IDs which are numbered sequentially but the IDs can be any number up to 31.

Example 2

The RAS hosts 1 NFAS group containing 3 PRIs

Signal setting for each WAN port

 

WAN 1

WAN 2

WAN 3

WAN 4

 

 

 

 

 

Switch Type

Nil (0)

nfsSlave(7)

nfsSlave(7)

Turned off

 

 

 

 

 

Interface ID

0

1

2

 

 

 

 

 

 

Primary WAN

1

1

1

 

 

 

 

 

 

Configuring Non-Facility Associated Signaling (NFAS)

316

Page 316
Image 316
Patton electronic 29XX manual Configuring Non-Facility Associated Signaling Nfas, Configuring Nfas