Preparing to Connect to a Network
Cisco 2600 Series Hardware Installation Guide
2-16
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 the online
document Cisco Modular Access Router Cabling Specifications on the Documentation
CD-ROM that accompanied your router, and on Cisco Connection Online.
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 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.
Table 2-2
Serial Signal Transmission Speeds and Distances
EIA/TIA-232
Distance
EIA/TIA-449, X.21, V.35, EIA-530
Distance
Rate (bps)
Feet
Meters
Feet
Meters
2400
200
60
4100
1250
4800
100
30
2050
625
9600
50
15
1025
312
19200
25
7.6
513
156
38400
12
3.7
256
78
56000
8.6
2.6
102
31
1544000 (T1)
–
–
50
15
