ISDN-LNK (ISDN-PRI Signaling Link Port)

Table 30. ISDN-LNK (ISDN-PRI Signaling Link Port)

MO Name (in Alarm Log)	Alarm Level	Initial Command to Run*	Full Name of MO
ISDN-LNK**	MINOR	test port GGGVSpp l	ISDN-PRI Signaling Link Port
ISDN-LNK	WARNING	test port GGGVSpp sh	ISDN-PRI Signaling Link Port
*pp is 24 for 24-channel interfaces and 16 for 32-channel interfaces.
Note: You must consult local records for the location and designation of the equipment rack where the G700 is mounted.
**For additional related information, see USD1-BD and DS1-MM MOs.

The ISDN-PRI interface uses out-of-band signaling (as opposed to robbed-bit, in-band signaling) to transmit control messages between two endpoints. User information channels carry digitized voice and digital data and are known as bearer channels (B-channels). B-channels are assigned to DS1 ISDN trunks or PRI endpoints. Call control signaling for the B-channels is combined and carried over the separate ISDN-PRI Signaling Link Port D-channel.

The ISDN-PRI Signaling Link Port (ISDN-LNK) is a port on a MM710, which has a direct interface to the packet bus which carries D-channel messages to the processor. The associated B-channels can use ports on the same Media Module or ports on other MM710s.

Two types of DS1 interfaces exist:

• 24 DS0 channels on a 1.544 Mbps link
• 31 DS0 channels + 1 framing channel on a 2.048 Mbps link

On 24-channel interfaces, the B-channels may use any of the first 23 ports. The signaling link is assigned to the 24th port. On 32-channel interfaces, the DS1 ISDN Trunks (B-channels) may use any of ports 1 to 15 and 17 through 31. The signaling link is assigned to the 16th port. The 32nd channel (port 0) is used for framing. In NFAS configurations, the 24th or 16th ports on some of the DS1 Media Modules may be used for B-channels. Refer to ISDN-SGR for further information.

A problem with the ISDN-LNK will have an effect on all of the associated B-channels since without it no call control information can be conveyed to the far-end switch or terminal adapter. Stable calls may remain operational, but no new calls can be made. The ISDN-LNK in turn depends on the MM710 it resides on which provides the link to the processor. If there are problems with the ISDN-LNK, also investigate the MM710 Interface Media Module (MG-DS1).