Synchronous Serial Connections; Dte Or Dce; Speed And Distance Limitations - Cisco 2500 Series Installation And Configuration Manual

Preparing to Install the Router

Synchronous Serial Connections

Before you connect a device to the synchronous serial port (labeled "SERIAL"), you will need to know
the following:
The type of device, DTE or DCE, you are connecting to the synchronous serial interface.
The type of connector, male or female, required to connect to the device.
The signaling standard required by the device.

DTE or DCE

A device that communicates over a synchronous serial interface is either a DTE or DCE device. A DCE
device provides a clock signal that paces the communications between the device and the router. A DTE
device does not provide a clock signal. DTE devices usually connect to DCE devices. The documentation
that came with the communications device should indicate whether it is a DTE or DCE device. (Some
devices have a jumper to select either mode.) If you cannot find the information in the documentation,
refer to to help you select the proper device type.
Table 2-1 Typical DTE and DCE
Devices (Continued)
Device Type Gender Typical Devices
DTE 1
Male
DCE
Female
1
If pins protrude from the base of the connector, the connector is male.
2
If the connector has holes to accept pins, the connector is female.
3
CSU/DSU = Channel service unit/data service unit.

Speed and Distance Limitations

Serial signals can travel a limited distance at any given bit rate; generally, the slower the data rate, the
greater the distance. All serial signals are subject to distance limits, beyond which a signal degrades
significantly or is completely lost.
Table 2-2 lists the maximum speeds and distances for EIA/TIA-232 signals. This signaling standard
supports unbalanced circuits at signal speeds up to 64 kbps.
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Terminal
PC
Router
2
Modem
3
CSU/DSU
Multiplexer