ISDN-SGR (ISDN-PRI Signaling Group)

Last Updated : Sep 29, 2023 |

MO name in log

Alarm level

Initial command to run 1

Full name of MO

ISDN-SGR

MIN

WRN

test signaling-group grp#

ISDN-PRI Signaling Group

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-Channel refers to an ISDN-TRK or PE-BCHL, depending on the application under investigation.

The following media modules are supported in the implementation of ISDN-PRI:

Media module

Channel types

Interface

MM710

B- and D-Channels

24 or 32 channel
These 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)

  • Non-Facility-Associated Signaling (NFAS)

  • Backup NFAS signaling

In a FAS signaling group, the 24th port of the DS1 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 Interface Media Module can carry D-channel signaling for B-Channels on several other DS1 Media Modules. The 24th port on the other media modules can be used as a B-Channel. A D-Channel in an NFAS group can signal for B channels on a total of 20 DS1 media modules.

D-channel backup provides increased reliability, which is highly desirable since NFAS permits a D-Channel to signal for many more B-Channels. NFAS allows the administration of a backup D-Channel that remains in a standby state until the active D-Channel goes down. If so, the backup D-Channel takes over and provides signaling for every B channel 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 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-PLK (ISDN-PRI Signaling Link Port), MG-DS1 (DS1 Interface Media Module), SYS-LINK (System Links).

1

grp# is the signaling group number (1–166); the test sequence can be either short or long.