AT&T DEFINITY 7200 series Guide de l'utilisateur Page 229

  • Télécharger
  • Ajouter à mon manuel
  • Imprimer
  • Page
    / 348
  • Table des matières
  • MARQUE LIVRES
  • Noté. / 5. Basé sur avis des utilisateurs
Vue de la page 228
SYNCHRONIZATION OF DIGITAL FACILITIES B-21
_ ______________________________________________________________________________________
_ ______________________________________________________________________________________
_ ______________________________________________________________________________________
RULE 2:
A node may use a facility as a backup only if the node at the other end is not using that same facility as a
backup.
EXAMPLE FOR RULE 2
Figure B-13, Proper Use of Backup Facilities, illustrates an application of rule 2 and proper use of a
backup facility between nodes A and C.
B
C
D
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIGITAL TRANSMISSION FACILITY
. . . . . . . . . . . . . . . . .
PRIMARY FREQUENCY REFERENCE
SECONDARY (BACKUP) FREQUENCY REFERENCE
A
Figure B-13. Proper Use of Backup Facilities
Figure B-14, Improper Use of Backup Facilities, shows the same network arrangement but with improper
use of the backup facility between nodes A and C. This improper arrangement would form a timing loop if
node B should fail (nodes A and C would switch to their backup, which is each other).
RULE 3:
The transmission facilities associated with those nodes meeting Rules 1 and 2 and having the greatest
availability must be selected for primary and secondary synchronization facilities.
Vue de la page 228
1 2 ... 224 225 226 227 228 229 230 231 232 233 234 ... 347 348

Commentaires sur ces manuels

Pas de commentaire