Huawei Technologies Proprietary 
4-14 
Description 
Attribute 
Synchronous  Asynchronous 
Service 
DDN leased line backup 
Terminal access 
Backup 
Modem dialup  
Backup 
Asynchronous lease 
line 
terminal access 
Protocol 
PPP 
MP 
LAPB 
HDLC 
X.25 
Frame Relay 
PPP 
SLIP 
MP 
 
z  Synchronous/asynchronous mode 
Synchronous/Asynchronous serial interface can work in either synchronous or 
asynchronous mode. Different signaling standards are supported in these two modes. 
V.35, V.24 (RS232), RS449, X.21, and EIA-530 support synchronous operating mode, 
while V.24 (RS232) supports asynchronous operating mode. The maximum 
transmission distance and baud rate of the signal vary with the operating mode. 
Table 4-10 Transmission rate and transmission distance of V.24 (RS232)/V.35 cable 
V.24 (RS232)  V.35 
Baud rate (bps) 
Maximum 
transmission 
distance (m) 
Baud rate 
(bps) 
Maximum transmission 
distance (m) 
2400 60  2400 1250 
4800 60  4800 625 
9600 30  9600 312 
19200 30  19200 156 
38400 20  38400 78 
64000 20  56000 60 
115200 10  64000  50 
–– ––  2048000 30