H3C MSR 20 User Manual page 154

154 C 4: F I
HAPTER LEXIBLE
n
Interface Attributes
C
NTERFACE ARDS
DTE and DCE
An FIC-SA card is usually connected to an external modem for dialing purpose,
where an appropriate baud rate setting is required.
The synchronous serial interface can work in either DTE or DCE mode. Two directly
connected devices must work as DTE and DCE respectively. The DCE provides clock
synchronization and specifies the communication rate, whereas the DTE accepts
clock synchronization and communicates at the specified rate.
The router normally works as a DTE. To identify whether the equipment connected
to the router is DTE or DCE, refer to the manual shipped with the equipment.
Speed and transmission segment of synchronous/asynchronous serial
interface
In different operating modes, the synchronous/asynchronous serial interface
supports different electric signal specifications and baud rates. In addition, the
maximum signal transmission segment depends not only on the specified baud
rate but also on the selected cable. The following table shows how the cable type,
baud rate, and the maximum signal transmission segment related to each other.
Table 108 Speed and transmission segment of the V.24 (RS232)/V.35 cable
V.24 (RS232)
Max. transmission
Baud rate (bps) segment
2400 60 m (196.9 ft.)
4800 60 m (196.9 ft.)
9600 30 m (98.4 ft.)
19200 30 m (98.4 ft.)
38400 20 m 65.6 ft.)
64000 20 m (65.6 ft.)
115200
- -
When a V.24 cable is used, the baud rate of the FIC-SA in synchronous mode shall
not exceed 64 Kbps.
The following table describes the interface attributes of the FIC-SAE:
Table 109 Interface attributes of the FIC-2SAE/FIC-4SAE/FIC-8SAE
Attribute
Connector
Number of connectors
V.35
Baud rate (bps)
2400
4800
9600
19200
38400
56000
10 m (32.8 ft.) 64000
2048000
Description
Synchronous
DB-28
2 (FIC-2SAE)
4 (FIC-4SAE)
8 (FIC-8SAE)
Max. transmission
segment
1250 (4101 ft.)
625 m (2050.5 ft.)
312 m (1023.6 ft.)
156 m (511.8 ft.)
78 m (255.9 ft.)
60 m (196.9 ft.)
50 m (164 ft.)
30 m (98.4 ft.)
Asynchronous