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
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