1.0 HDSL Systems
RS8953B/RS8953SPB
1.1 HTU Applications
HDSL Channel Unit
1.1.5 Point-to-Multipoint
Figure 1-6 shows fractional T1/E1 services delivered from the CO to multiple
remote sites in a Point-to-Multipoint (P2MP) application. The number of HDSL
wire pairs and PCM channel rates at each site is variable. The RS8953B provides
the ability to measure and compensate for misalignment between separate PCM
frame syncs coming from each remote site. By programming transmit delays from
PCM to HDSL frame syncs, each remote site can send its HDSL frames back to
the central office. The HDSL frames are then sufficiently aligned with the others
to be reconstructed into a single PCM frame at the central site. The RS8953B
accommodates large differential delays associated with the P2MP application. It
receives HDSL frame offsets to groom Channel Associated Signaling (CAS)
from different sites.
P2MP applications of primary rate ISDN transport are also supported, where
different LAPD channels are received from each remote site. The RS8953B
provides auxiliary HDSL channel inputs and outputs for the system to externally
insert and monitor transmitted or received HDSL payload bytes. Auxiliary HDSL
channels may alternately be configured to terminate the last 40 Z-bits through an
external data link controller.
Figure 1-6. Point-to-Multipoint (Fractional) System Block Diagram
LAPD Signaling or
Management Protocol
Optional
SCC
SCC
SCC
Site A
Partial
T1/E1
CH1
CH1
CH1
RS8953B
CH1
Site B
Partial
T1/E1
RS8953B
Full
T1/E1
RS8953B
CH2
CH3
Site C
Partial
T1/E1
RS8953B
NOTE(S):
1. SCC = Serial Communications Controller
2. LAPD = Link Access Procedure D-Channel
3. AUX = Auxiliary HDSL channel attaches to payload or Z-bits
1-6
Conexant
N8953BDSB
CONEXANT [ CONEXANT SYSTEMS, INC ]
