Communications System Owner Manual

ManualsBrandsAT&T ManualsNetwork RouterDEFINITY 7400 series

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Table Of Contents

Table of Contents
ABOUT THIS DOCUMENT
- PREREQUISITE SKILLS AND KNOWLEDGE
- DOCUMENT ORGANIZATION
- HOW TO MAKE COMMENTS ABOUT THIS DOCUMENT
1. INTRODUCTION TO CONNECTIVITY
- TRANSMISSION TYPES
- TRANSMISSION STATES
  - VOICE TRANSMISSION
    - Entering the Switch
    - Exiting the Switch
  - DATA TRANSMISSION
- MULTIPLEXED COMMUNICATION
- TRUNKING
2. COMMUNICATION SYSTEM NETWORKING (em AN OVERVIEW
- TYPES OF NETWORKS
- NETWORK EVOLUTION
- SOFTWARE CAPABILITIES
- NETWORK CALL PROCESSING
- NETWORK ADMINISTRATION
- PRIVATE NETWORK TRUNKS
- NETWORKING FEATURE PARAMETERS
3. TANDEM TIE TRUNK NETWORKS
- INTERACTIONS WITH OTHER NETWORKS
4. MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES
- MS/T CONFIGURATIONS
  - Main-Satellite Configuration
  - Main-Tributary Configuration
- MS/T FEATURES
- ENGINEERING CONSIDERATIONS
- INTERACTIONS
5. ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES
- ETN CONFIGURATIONS
- ETN TRUNKS
  - Access and Bypass Access Tie Trunks
  - Off-Net Trunks
- FEATURES
- ETN INTERACTIONS WITH OTHER NETWORKS
- ENGINEERING CONSIDERATIONS
6. DISTRIBUTED COMMUNICATIONS SYSTEM (DCS)
- DCS CLUSTERS
- DCS LINKS
  - Tie Trunks
  - Signaling Links
- DCS SIGNALING LINK CONNECTIONS
- TRANSPARENT FEATURES
- ENGINEERING CONSIDERATIONS
- ADMINISTRATION CONSIDERATIONS
7. DATA CONNECTIVITY - AN OVERVIEW
- DATA COMMUNICATIONS VARIABLES
- SPECIAL DATA FEATURES
8. DATA COMMUNICATIONS CAPABILITIES
- DTE CONNECTIONS
- LOCAL AREA NETWORK CONNECTIONS
- PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS
  - PUBLIC DATA NETWORKS
    - Packet-Switched Public Data Networks
    - Circuit-Switched Public Data Networks
  - PRIVATE DATA NETWORKS
    - Terrestrial Private Data Network Links
    - Satellite Private Data Network Links
- TELEMARKETING HOST CONNECTIONS
  - THE ISDN GATEWAY
  - THE INTEGRATED TELEMARKETING GATEWAY
- DATA NETWORK ADMINISTRATION
9. DATA COMMUNICATIONS CONFIGURATIONS
- DSC AND PSC CONNECTIONS
- SNA NODE CONNECTIONS
- CONNECTIONS THROUGH PUBLIC OR PRIVATE DATA NETWORKS
A. RELATED DOCUMENTS
B. SYNCHRONIZATION OF DIGITAL FACILITIES
- THE NEED FOR SYNCHRONIZATION
- SYNCHRONIZATION HIERARCHY
- CHANGES TO THE SCS SOFTWARE MADE AVAILABLE VIA SOFTWARE PATCHES
- NETWORK SYNCHRONIZATION AND ENGIINEERING
- AVAILABILITY OF SYNCHRONIZATION SOURCES
- CONCLUSIONS ON SYNCHRONIZATION
- USE OF GENERIC 2 AS A SYSTEM CLOCK REFERENCE
- USE OF GENERIC 1 AS A SYSTEM CLOCK REFERENCE
C. TRUNKING TERMS AND CAPABILITIES
D. COMMUNICATIONS PROTOCOLS
- OSI MODEL
- STANDARD PROTOCOLS
- AT&T PROTOCOLS
E. LEAD DEFINITIONS
F. NETWORKING FEATURES - AVAILABILITY MATRIX
ABBREVIATIONS
GLOSSARY
INDEX

B-22 SYNCHRONIZATION OF DIGITAL FACILITIES

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DIGITAL TRANSMISSION FACILITY

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PRIMARY FREQUENCY REFERENCE

SECONDARY (BACKUP) FREQUENCY REFERENCE

Figure B-14. Improper Use of Backup Facilities

Availability is deﬁned as the ratio of the mean time between failures (the average time between successive

system failures, abbreviated MTBFs) to the sum of the MTBFs and the mean time to repair (the total

maintenance time divided by the total number of failures during the same amount of time abbreviated

MTTR). Low availability (poor transmission performance) is used as a criterion to reject a facility as a

reference candidate or to reassign one already chosen.

Characteristics that primarily determine the availability of a transmission facility are rank-ordered as

follows:

1. History record

2. Activity

3. Facility length

4. System rate (that is, whether the facility supports T1 or ﬁber)

5. Protection switching

6. Physical type (that is, whether the facility is physically installed as an underground, buried, or aerial

paired cable, a coaxial cable, or a radio link). (Satellite facilities should not be used to supply

synchronization.)

7. Number and type of regenerative repeaters

8. Number of digital terminal products and other intermediate ofﬁce equipment, if any