3Com 3C13701 Installation Manual page 31

Connecting WAN
Interface to DSU/CSU
Connecting Synchronous/Asynchronous Serial Interface to DSU/CSU
Introduction to the Synchronous/Asynchronous Serial Interface. The fixed WAN
interface of 3Com 5000 Routers is a synchronous/asynchronous serial interface, which is
usually used for the connection with a WAN device, such as a Modem or CSU/DSU. It can
operate in the synchronous/asynchronous mode or DTE/DCE mode, depending on the
application. For the attributes of the interface, please refer to Table 16.
Table 16 Attributes of the synchronous/asynchronous serial interface
Attribute
Connector type
Interface standard and
operating mode
Minimum baud rate (bps)
Maximum baud rate (bps)
Matching cable
Function
Protocol
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 and V.24 (RS232) support synchronous operating mode, while V.24 (RS232),
support the asynchronous operating mode. The maximum transmission distance and
baud rate of the signal vary with the operating mode.
Synchronous
DB28 or DB50
V.24 V.35/X.21
DTE/DCE DTE/DCE
1200 1200
64K 2.048M
V.24 (RS232) DTE cable
V.24 (RS232) DCE cable
V.35 DTE cable
V.35 DCE cable
X.21 DTE cable
X.21 DCE cable
DDN leased line backup
Terminal access
PPP
MP
LAPB
HDLC
X.25
Frame Relay
Connecting Router to the WAN
Description
Asynchronous
RS232
300
115200
Modem dial-up
Backup
Asynchronous lease line
terminal access
PPP
SLIP
MP
31