Transmission Speeds And Distance Limitations; Asynchronous/Synchronous Serial Module Baud Rates; Isdn Bri Connections - Cisco 1900 series Hardware Installation

Chapter 2 Preparing for Router Installation
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
Cable

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 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)
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:
•
•

ISDN BRI Connections

The BRI WICs provide Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI)
connections. BRI WICs are available with either an S/T interface that requires an external Network
Termination 1 (NT1), or a U interface that has a built-in NT1. You can install the BRI WICs in any
available WIC slots in the chassis.
OL-19084-02
Specifications.
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
25 7.6
12 3.7
8.6 2.6
— —
Asynchronous interface—Maximum baud rate is 115.2 kbps.
Synchronous interface—Maximum baud rate is 128 kbps, full-duplex.
Distance for
EIA/TIA-449, X.21, V.35,
and EIA-530 Distance for USB
Feet Meters Feet
4100 1250 16.4
2050 625 16.4
1025 312 16.4
513 156 16.4
256 78 16.4
102 31 16.4
50 15 16.4
Cisco 1900 Series Hardware Installation
Preparing to Connect to a Network
Cisco Modular Access Router
Meters
5
5
5
5
5
5
5
2-9