Installation guide

4-62 Cisco 4000 Series Installation Guide
Network Connection Considerations
used. If you understand the electrical problems that might arise and can compensate for
them, you can get good results with rates and distances greater than those shown. However,
do so at your own risk.
Table 4-5 IEEE Standard Transmission Speeds and Distances
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232.
The recommended distance limits for EIA/TIA-449 shown in Table 4-5 are also valid for
V.35, X.21, and EIA-530. However, you can get good results at distances and rates greater
than those shown in Table 4-5. Typically, EIA/TIA-449 and EIA-530 support 2-Mbps rates,
and V.35 can support 4-Mbps rates.
EIA/TIA-232 Connections
EIA/TIA-232 supports unbalanced circuits at signal speeds up to 64 kbps. The network end
of the adapter cable is a standard 25-pin D-shell connector known as a DB-25. (See
Figure 4-14.) The router console and auxiliary ports also use EIA/TIA-232 connections;
however, the serial module ports support synchronous connections, and the console and
auxiliary ports support asynchronous connections.
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) N/A N/A 50 15