Avaya G250 Maintenance Manual page 170

Avaya Communication Manager controlled maintenance
An ISDN-PRI Signaling Group is a collection of B-channels for which a given ISDN-PRI
Signaling Channel Port (D-channel) carries signaling information. B-channels carry voice or
data and can be assigned to DS1 ISDN trunks (ISDN-TRK) or PRI endpoint ports (PE-BCHL).
Note:
Throughout this discussion the term B-channels refers to ISDN-TRKs or
Note:
PE-BCHLs, depending on the application under investigation.
The MM710 Interface media module, which has a direct interface to the packet bus, is required
for D-channel signaling. There are two types of DS1 interfaces:
24 DS0 channels on a 1.544 Mbps link
●
31 DS0 channels + 1 framing channel on a 2.048 Mbps link
●
The following discussion describes 24-channel interface signaling groups. The 32-channel
interface works the same way, except that only port number 16 is used for signaling instead of
port number 24. Ports 1 through 15 and 17 through 31 are used for B-channels. The 32nd
channel (port 0) is always used for framing.
ISDN-PRI D-channel signaling can be combined with a group of B-channels in three basic
ways:
Facility-associated signaling (FAS)
●
Nonfacility-associated (NFAS) simplex signaling
●
NFAS duplex signaling
●
In a FAS signaling group, the 24th port of the DS1 MM Interface media module carries
D-channel signaling for up to 23 B-channel ports on the same media module.
In an NFAS signaling group, the 24th port of one DS1 MM Interface can carry D-channel
signaling for B-channels on several other DS1 media module as well, including TN767s and
TN464Bs. The 24th port on the other media modules can be used for B-channels. A D-channel
in an NFAS group can signal for B-channels on a total of 20 DS1 media modules.
NFAS duplex signaling provides increased reliability, which is highly desirable since NFAS
permits the D-channel to signal for many more B-channels. NFAS Duplex allows the
administration of a backup D-channel which remains in a standby state until the active
D-channel goes down. If the active D-Channel does go down, the backup D-Channel takes over
and provides signaling for all the B-channels in the signaling group.
The operation of the entire ISDN-PRI signaling group depends on several other entities: the
ISDN-PRI signaling channel ports, the MG-DS1 Interface media module on which the
D-channels reside and the system link that is carried over the packet bus to the processor.
When there are problems with the ISDN-PRI signaling group, also investigate ISDN-LNK,
MG-DS1, and SYS-LINK.
170 Maintenance for the Avaya G250 and Avaya G350 Media Gateways