AT&T Telephone DS1/DMi/ISDN-PRI Uživatelský manuál stáhnout pdf (Strana 57)

2. NETWORK CONNECTIONS AND CONFIGURATIONS

This chapter provides a description of common connection arrangements with System 85 R2V4,

DEFINITY

Communications System Generic 1 and Generic 2. These connections include private

network, public network, and those made through digital signal level 1 (DS1) auxiliary equipment.

Also included is a description of the services provided by each connection, any option restrictions,

and relevant synchronization issues.

The equipment used for completing the end-to-end connection may include any of the options

described in chapter 3, DS1 Transmission and Cabling. These options permit distances between

endpoints of a few feet to thousands of miles. Detailed information, such as that required to install

and administer a connection, is contained in chapter 6, Port Types/Installation Compatibilities, and

chapter 7, Administration Options and Requirements. Common field problems relating to these

connections are described in Appendix B, Sample Installation and Maintenance Problems. A

complete description of synchronization is provided in chapter 5, Synchronization of Digital Facilities,

and loss adjustments are described in chapter 4, The Digital Loss Plan.

NETWORK DIFFICULTIES

Two of the many difficulties that can exist on public and private networks are hyperactivity and glare.

Before describing connection arrangements, the methods for dealing with these two difficulties is

discussed.

Hyperactivity

When a DS1 facility generates an abnormally high stimulus rate originating from and individual

source over a certain amount of time (such as rapid on-hook and off-hook conditions), it is said to be

hyperactive. The call-processing software can not handle the flood of stimuli, resulting in dial-tone

delays. Hyperactivity can be caused by bit errors on the facility, misoptioned equipment, or

hardware failures. Severe or long-lasting hyperactivity can overload the communications system with

more messages than it can process. Without intervention and corrective action, this could result in

degradation or even loss of service on the switch.

On Generic 2, special software handles hyperactivity by executing the following steps:

Detecting the presence of possible hyperactivity

Identifying a suspected source of hyperactivity

Examining the suspected source

Arresting the message flow from the suspected port, usually protecting the communications

system from excessive stimuli

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AT&T Telephone DS1/DMi/ISDN-PRI Uživatelský manuál Strana 57