Lucent Technologies 8.2 Manuale Utente

Issue 1

April 2000

Features and technical reference 

1334

Facility and Non-Facility Associated Signaling 

Coordinate the following when implementing FAS and NFAS:

■

Decide which T1/E1 facilities will use FAS.

■

Decide which of the remaining T1/E1 facilities carries D-channel signaling 
information on the 16th (E1) or 24th (T1) channel. For those channels that 
have a D-Channel Backup, D-channel pairs must be allocated.

■

Define Signaling Groups. A Signaling Group is a group of B-channels for 
which a given D-channel (or D-channel pair) carries the signaling 
information. Each Signaling Group must be designated as either a FAS or 
NFAS Signaling Group.

— A FAS Signaling Group must contain all the ISDN B-Channels on 

the T1/E1 interface associated with the group’s D-channel, and 
cannot contain B-channels from any other DS1 circuit pack. For 
24-channel DS1 boards, some of the DS1 ports may use in-band 
(robbed-bit) signaling and be members in a tie trunk group rather 
than an ISDN trunk group. These tie trunks cannot be members of a 
Signaling Group.

— There is no restriction on which T1/E1 ports can belong to an NFAS 

Signaling Group. Normally, an NFAS Signaling Group consists of 
one or two D-channels and several complete T1/E1 interfaces.

— If a Signaling Group contains only a subset of a T1/E1’s B-channels 

(ports 1–12, for example), it is considered an NFAS Signaling 
Group, not a FAS Signaling Group. The remaining B-channels on 
the T1/E1 are then assigned as members of another NFAS Signaling 
Group.

■

An Interface ID must be assigned to each T1/E1 facility in an NFAS 
Signaling Group. For example, if the B-channels in a Signaling Group span 
3 T1/E1 facilities, a unique Interface ID must be assigned to each of the 3 
facilities. This designation is required to uniquely identify the same 
B-channel (port) number on each of the T1/E1 facilities in the Signaling 
Group. Therefore, this interface must be agreed upon by both sides of the 
interface and administered prior to initialization.

■

Primary and Secondary D-Channel Backup must be agreed upon by both 
sides of the interface and administered prior to initialization. If the IDs do 
not match, the signaling group will come up but calls will fail.

The following screens show the DS1 interface configuration for NFAS. When 
implementing FAS and NFAS, the DS1 screen must be submitted first, followed 
by the Interface Link and associated forms, followed by the ISDN-PRI trunk 
group, Signaling Group, and Trunk Group Members forms.