Lucent Technologies DEFINITY Communications System Generic 2.2 And Generic 3 V2 DS1/CEPT1/ISDN PRI Reference Manual

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-37 Synchronization 
4
Figure 4-6. Synchronization Hierarchy
Switching nodes in digital networks are divided into synchronization layers called 
strata. There are four strata, 1 to 4, where stratum 1 has the highest ac c urac y 
and  stratum 4 the lowest. Pub lic  d igital networks use stratum 1, 2, and 3 
sync hronization. Historic ally, p rivate d ig ital...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-38 Synchronization 
4
Dig ital Servic e (DDS). Outsid e the United  States, AT&T p rovid es a stratum-1 
c loc k through the Private Network Customer Expert System, Synchronization and 
Timing , Servic e (PRINCE — S, T).
The p ub lic  d ig ital network nod es and  servic es that the AT&T p rivate d ig ital 
switc hes and  d igital terminal p rod uc ts c an c...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-39 Synchronization 
4
Figure 4-7. Stratum Levels for the Synchronization Hierarchy
The minimum c loc k ac c urac y for eac h stratum level is as follows:
nStratum 1 (\(+ - 0.00001 pp m, most ac c urate)
nStratum 2 (\(+ - 0.016 p p m, more ac c urate than stratum 3)
nStratum 3 (\(+ - 4.6 p p m, more ac c urate than stratum 4)
nStratum 4 (\(+ - 32 ppm, least acc...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-40 Synchronization 
4
Synchronization Architecture and Operations
The timing  ac c urac y availab le to a c ommunic ations system d epend s on 
c ommunic ations system version and  the typ e of sync hronization c irc uit b oard it 
uses. Tab le 4-11
 lists the sync hronization b oard s that are availab le, the versions 
of the switc h in which they are...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-41 Synchronization 
4
TN463 Synchronization Architecture
When the TN463 c irc uit b oard  is installed , Generic  2.2 c ommunic ations systems 
c an func tion as either timing  slaves or timing  masters. As a slave, the switc h 
rec eives d ig ital d ata from one or two DS1s. One interfac e sup p lies the p rimary 
sync hronization referenc e and the other...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-42 Synchronization 
4
ap plic ations. The switc h arc hitec ture d etermines the equip ment c arriers that will 
c ontain the SCS c irc uit p ac ks.
For sing le-mod ule ap p lic ations, the SCS is loc ated  in the mod ule c ontrol c arrier. 
In ad d ition to the SCS, a mod ule c loc k is also req uired . The SCS c ontrols the 
mod ule c loc k. For multimodule...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-43 Synchronization 
4
uses the system status to keep the best inc oming  DS1 referenc e c loc k online. 
The other is c ontrolled  b oth b y hard ware and  the 1-sec ond software task to 
maintain a healthy SCS on line. If a SCS c an rec eive a suitab le referenc e c loc k 
from a DS1, then the b est c omb ination is c hosen. 
Criteria for Switching Reference...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-44 Synchronization 
4
DS1 referenc e c loc k, a hig h-p riority req uest for a soft switc h is mad e. The offline 
SCS is also monitored  to make sure that a switc h is not attemp ted  to an unhealthy 
SCS. If the SCS is not d up lic ated  and  the HAC is healthy, serious failures c ause a 
switc h to the HAC to ensure switc h reliab ility. When the SCS c an...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-45 Synchronization 
4
nThe LED in p osition #5 refers to the sec ond ary DS1 referenc e. The LED is 
OFF if a sync hronization sig nal is p resent and  the SCS is c ap able of 
loc king . The #5 LED is ON if an error c ond ition exists and  the 
sync hronization c ab le is p resent.
nThe following  four yellow LEDs ind ic ate the selec ted  timing  referenc e:...

DEFINITY Communications System Generic 2.2 and Generic 3 V2 
DS1/CEPT1/ISDN PRI Reference  
555-025-107  Issue 1
July 1993
Physical Layer 
Page 4-46 Synchronization 
4
Figure 4-10. Internal Tone-Clock Synchronizer (G3V2)
Software Operation
G3V2 sync hronization software d iffers slig htly from Generic  2.2 b ec ause of 
arc hitec tural d ifferenc es; however, b oth switc hes p rovid e the same overall 
func tions. Primarily, these func tions inc lud e monitoring  the sync hronization 
referenc es and...