NFAS configuration examples Introduction

Introduction

In systems with multiple T1 ISDN trunks, some customers prefer using a non-facility associated signaling (NFAS) configuration in order to gain extra B-channels.

Background

This article provides example configurations for NFAS groups in the board configuration files.

Details

NFAS group information is associated with the trunk on which the primary D-channel is located. A unique number must be assigned to each NFAS group for reference:

NetworkInterface.T1E1[x].ISDN.NFASGroup             - group number

 For each NFAS group member (including primary D-channel) following configuration information should be specified:

NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].Board   - board number
NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].Trunk   - trunk number (from 0)
NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].NAI     - assigned NAI number unique within group

where:

     x = trunk number for primary D-channel

     y = NFAS member number (starting at 0 without any gaps in numbering)

Example 1

   Group #5, D-channel on trunk 0

   Members:  

      0 - NAI 4, Trunk 0, this board ( number 0 )

      1 - NAI 6, Trunk 1, this board ( number 0 )

 Signaling settings for trunk with D-channel:

NetworkInterface.T1E1[0].D_Channel                 = ISDN
NetworkInterface.T1E1[0].SignalingType             = PRI

 Signaling settings for trunk without D-channel:

NetworkInterface.T1E1[1].D_Channel                 = ISDN_NONE
NetworkInterface.T1E1[1].SignalingType             = RAW

Assigning group number (to D-channel trunk):

NetworkInterface.T1E1[0].ISDN.NFASGroup            = 5           

Configuring group members:

NetworkInterface.T1E1[0].ISDN.NFAS_Member[0].Board = 0
NetworkInterface.T1E1[0].ISDN.NFAS_Member[0].Trunk = 0
NetworkInterface.T1E1[0].ISDN.NFAS_Member[0].NAI   = 4

NetworkInterface.T1E1[0].ISDN.NFAS_Member[1].Board = 0
NetworkInterface.T1E1[0].ISDN.NFAS_Member[1].Trunk = 1
NetworkInterface.T1E1[0].ISDN.NFAS_Member[1].NAI   = 6

Example 2

   Group #3, D-channel on trunk 2

   Members:  

      0 - NAI 4, Trunk 2, this board ( number 0 )

      1 - NAI 6, Trunk 3, this board ( number 0 )

Signaling settings for trunk with D-channel:

NetworkInterface.T1E1[2].D_Channel                 = ISDN
NetworkInterface.T1E1[2].SignalingType             = PRI 

Signaling settings for trunk without D-channel:

NetworkInterface.T1E1[3].D_Channel                 = ISDN_NONE
NetworkInterface.T1E1[3].SignalingType             = RAW

Assigning group number (to D-channel trunk):

NetworkInterface.T1E1[2].ISDN.NFASGroup            = 3           

Configuring group members:

NetworkInterface.T1E1[2].ISDN.NFAS_Member[0].Board = 0
NetworkInterface.T1E1[2].ISDN.NFAS_Member[0].Trunk = 2
NetworkInterface.T1E1[2].ISDN.NFAS_Member[0].NAI   = 4
 
NetworkInterface.T1E1[2].ISDN.NFAS_Member[1].Board = 0
NetworkInterface.T1E1[2].ISDN.NFAS_Member[1].Trunk = 3
NetworkInterface.T1E1[2].ISDN.NFAS_Member[1].NAI   = 6

Product List

All Dialogic CG series digital boards.

Glossary of Acronyms / Terms

 NFAS:  Non-facility associated signaling; a mode in which a single D-channel on a T1 trunk carries the signaling for all B-channels on several T1 trunks. This leaves the 24th channels on the trunks without a D-channel free for use as B-channels. NFAS is not supported on E1 trunks.