Signaling Standards Supported; Distance Limitations - Cisco MWR 1941-DC - 1941 Mobile Wireless Router Hardware Installation Manual

Preparing to Connect to a Network

Signaling Standards Supported

The synchronous serial ports available for the router support the following signaling standards:
EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA-530. You can order a Cisco DB-60 shielded serial
transition cable that has the appropriate connector for the standard you specify. The documentation for
the device you want to connect should indicate the standard used for that device. The router end of the
shielded serial transition cable has a DB-60 connector, which connects to the DB-60 port on a serial
WAN interface card. The other end of the serial transition cable is available with a connector appropriate
for the standard 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
Technical Assistance" section on page
Note All serial ports configured as DTE require external clocking from a CSU/DSU or other DCE device.
Although manufacturing your own serial cables is not recommended (because of the small size of the
pins on the DB-60 serial connector), cable pinouts are provided in

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.
Note Only the serial WAN interface card supports bit rates above 128 Kbps.
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 Mbps, but 4 Mbps is commonly used.
Table 2-2
Rate (bps)
2400
4800
9600
19200
38400
56000
1544000 (T1)
Cisco MWR 1941-DC Mobile Wireless Edge Router Hardware Installation Guide
2-10
lists the recommended maximum speeds and distances for each serial interface type; however,
Serial Signal Transmission Speeds and Distances
EIA/TIA-232
Distance
Feet Meters
200 60
100 30
50 15
25 7.6
12 3.7
8.6 2.6
— —
xiii.
EIA/TIA-449, X.21, V.35,
EIA-530 Distance
Feet Meters
4100 1250
2050 625
1025 312
513 156
256 78
102 31
50 15
Chapter 2 Preparing to Install the Router
"Obtaining
Appendix B, "Cable Specifications."
78-15827-06B0