AT&T DS1/DMi/ISDN-PRI manual Figure B-10.Leavenworth Loop on the Primary Reference

B-l0SAMPLE INSTALLATION AND MAINTENANCE PROBLEMS

DS1 OR DMI

INTERFACE

LOCATION A

PRIMARY REFERENCE

PRIMARY REFERENCE

DS1 OR DMI

INTERFACE

LOCATION B

Figure B-10.Leavenworth Loop on the Primary Reference

DS1 OR DMI				DS1 OR DMI
INTERFACE		SECONDARY REFERENCE		INTERFACE
LOCATION A	SECONDARY REFERENCE			LOCATION B
		PRIMARY	REFERENCE
		DS1	OR DMI
		INTERFACE
		LOCATION C

Figure B-11.Leavenworth Loop on the Secondary Reference

Make no assumptions when synchronizing digital networks; don’t take any aspect of synchronization for granted and avoid Leavenworth loops. It is better to suffer the problems from high slip rates than to risk losing all services provided by the switch.

It is necessary that the network synchronization diagram be maintained and be available at all switch locations.

D4 Synchronization Problems

The D4-channel banks are used in a variety of applications. Primarily, these include interfacing an analog switch or analog CO to a digital switch. The D4-channel bank is capable of internal stratum-4 timing, or loop timing via the office interface unit (OIU-1/OIU-2) circuit pack located in the