Cisco ASR 5000 Application Detection and Control Administration Guide Hardware Installation Manual page 16

Network Cabling Specifications
Serial DTE or DCE Devices
A device that communicates over a synchronous serial interface is either a DCE or DTE 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 accompanied the device should indicate whether it is a DTE or DCE device. (Some devices have a
jumper to select either DTE or DCE mode.)
Table 2-1
Device Type
DTE
DCE
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.
Signaling Standards Supported
The synchronous serial ports available for the router support the following signaling standards:
EIA/TIA-232 (EIA-323). You can order a Cisco DB-25 shielded serial transition cable that has the
appropriate connector for the standard you specify. The documentation for the device should indicate the
standard used for that device. The router end of the shielded serial transition cable has a DB-25
connector, which connects to the DB-25 port on the router. The other end of the serial transition cable is
available with a connector appropriate for the standard you specific.
The synchronous serial port can be configured as DTE or DCE, depending on the attached cable.
All serial ports configured as DTE require external clocking from a CSU/DSU or other DCE device.
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 significantly
degrades or is completely lost.
Table 2-2
you might get good results at speeds and distances greater than those listed, if you understand the
electrical problems that might arise and can compensate for them. For instance, the recommended
maximum rate for V.35 is 2 Mb/s, but 4 Mb/s is commonly used.
Table 2-2
Rate (bps)
2400
4800
9600
Cisco 1120 Connected Grid Router Hardware Installation Guide
2-6
Typical DTE and DCE Devices
Gender
1
Male
2
Female
lists the recommended maximum speeds and distances for each serial interface type; however,
Serial Signal Transmission Speeds and Distances
Distance for
EIA/TIA-232
Feet Meters
200 60
100 30
50 15
Chapter 2
Table 2-1 lists typical DTE and DCE devices.
Typical Devices
Terminal
PC
Modem
CSU/DSU
Multiplexer
Distance for X.21 and
V.35
Feet Meters
4100 1250
2050 625
1025 312
Installation Safety and Site Preparation
Distance for USB
Feet Meters
16.4 5
16.4 5
16.4 5
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