3-5
Cisco 1900 Series Hardware Installation
OL-19084-01
Chapter 3 Cable Information and Specifications for Cisco 1900 Series Routers
Preparing to Connect to a Network
the shielded serial transition cable has a DB-60 connector, which connects to the DB-60 port on a serial
WIC. The other end of the serial transition cable is available with a connector appropriate for the
standard that you specify.
The synchronous serial port can be configured as DTE or DCE, depending on the attached cable (except
EIA-530, which is DTE only). To order a shielded cable, contact customer service. See the “Obtaining
Documentation and Submitting a Service Request” section on page xvi.
Note All serial ports configured as DTE require external clocking from a channel service unit/data service unit
(CSU/DSU) or other DCE device.
Although we do not recommend manufacturing your own serial cables (because of the small size of the
pins on the DB-60 serial connector), cable pinouts are provided in the Cisco Modular Access Router
Cable Specifications.
Transmission Speeds 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 is
significantly degraded or is completely lost.
Table 3-2 lists the recommended maximum speeds and distances for each serial interface type; however,
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 Mbps, but 4 Mbps is commonly used.
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232 signals.
Typically, EIA/TIA-449 and EIA-530 can support a 2-Mbps rate, and V.35 can support a 4-Mbps rate.
Asynchronous/Synchronous Serial Module Baud Rates
The following baud-rate limitations apply to the slow-speed serial interfaces in the
asynchronous/synchronous serial modules:
• Asynchronous interface—Maximum baud rate is 115.2 kbps.
Tab l e 3-2 Serial Signal Transmission Speeds and Distances
Distance for
EIA/TIA-232
Distance for
EIA/TIA-449, X.21, V.35,
and EIA-530 Distance for USB
Rate (bps) Feet Meters Feet Meters Feet Meters
2400 200 60 4100 1250 16.4 5
4800 100 30 2050 625 16.4 5
9600 50 15 1025 312 16.4 5
19200 25 7.6 513 156 16.4 5
38400 12 3.7 256 78 16.4 5
56000 8.6 2.6 102 31 16.4 5
1544000 (T1) — — 50 15 16.4 5