Lucent Technologies 555-661-150 manual Pstnpstn

MERLIN LEGEND Communications System Release 6.1	Issue 1
Network Reference 555-661-150	August 1998
5 Network Management
General Programming in Private Networks	Page 5-7

source is a Digital Signal 1 (DS1) facility connected to a long-distance carrier rather than a local exchange carrier. A second choice is a Basic Rate Interface (BRI) or PRI facility connected to any PSTN carrier. The Feature Reference outlines these choices and other alternatives in its “Primary Rate Interface (PRI) and T1” section.

Clock synchronization derived from the PSTN, either via PRI or BRI facilities, is always preferable to a clock source that is provided by a digital tandem facility that is not connected to the PSTN. Private networked systems, however, may not have an in-service digital PSTN facility available or active. For this reason, clock synchronization in some private networks requires choosing from among other clock sources. This is accomplished by programming the clock sources as local (clock synchronization if provided by a 100D module installed in the local system) or loop (clock synchronization is provided by a DS1 module installed in a non- local system). There should be no more than one local clock source for digital tandem facilities in a private network, and all other tandem facilities are assigned as loop. A local clock source in a private network is not required; all can be programmed as loop.

In a private network with three or more systems, it is best if all clock sources for the private network are on either a hub system (star configuration) or a system that connects two other switches (series configuration). If the primary clock source is not functioning, then a secondary or tertiary source on such a system can serve either all other systems in the private network or two other systems in a private network. The following examples illustrate how clock synchronization can be implemented in a private network.

PSTNPSTN

	100D
		tandem
System A
		PRI

100D

100D100D

tandem 100D100D

PRI

Primary: Loop	System B	System C
Secondary: Local	Primary: PSTN Loop	Primary: Loop B
Tertiary: ______	Secondary: Local C	Secondary: PSTN Loop
	Tertiary: Local A	Tertiary: Local B

1.If tandem digital facilities link the systems in a private network and a non- local system is connected to functional digital PSTN facilities, a system with no digital PSTN facilities assigns its digital tandem lines as loop to derive the clock source from the system connected at the other end of the link. Synchronization is derived from the PSTN connection on one private networked system. The system connecting to the PSTN also assigns its clock source as loop because its clock source is at the far end of the PSTN