T1 / T3 Services (2)
T1 it is DS1 delivered over copper wire (throughput 1.536 Mbps; bandwidth 1.544 Mbps (8Kbps lost for channel synchronization))
- ISDN PRI = 23 B + D Primary Rate Interface; T1 = 24 DS0
T3 it is DS3 delivered over copper wire ( throu 43.008 Mbps; bw 44.736 Mbps )
Synchronization within one 64 Kbps channel
- AMI - Alternate Mark Inversion - encoding for 56 Kbps channel
- B8ZS- Bipolar 8 Zero Substitution - encoding for 64 Kbps channel
In T1 we need to put 24 channels on one four-wire circuit
- TDM - Time Division Multiplexing
How to identify the first channel in 24-channel rotation ?
- D4 - Super Frame : = 12 frame format
- ESF - Extending Super Frame (framing); enhancement of D4 based on 24 frames