Cisco 7000 Series Hardware Installation And Maintenance Manual page 69

Table 2-6 IEEE Standard EIA/TIA-232C Transmission Speed versus Distance
Rate (bps) Distance (Feet)
2400 200
4800 100
9600 50
19200 25
38400 12
56000 8.6
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232.
Table 2-7 shows the standard relationship between bit rate and distance for EIA/TIA-449 signals.
Table 2-7 IEEE Standard EIA/TIA-449 Transmission Speed versus Distance
Rate (bps) Distance (Feet)
2400 4100
4800 2050
9600 1025
19200 513
38400 256
56000 102
128000 76
256000 50
1544000 (T1) 50
2000000 40
4000000 25
The recommended distance limits for EIA/TIA-449 shown in Table 2-7 are also valid for
Note
V.35, X.21, and EIA-530. However, you can get good results at distances and rates far greater than
these. In common practice, EIA/TIA-449 and EIA-530 support 2-Mbps rates, and V.35 supports
4-Mbps rates without any problems.
SONET Connections for the AIP
The SONET specification for fiber-optic transmission defines two types of fiber: single mode and
multimode. Modes can be thought of as bundles of light rays entering the fiber at a particular angle.
Single-mode fiber allows only one mode of light to propagate through the fiber, while multimode
fiber allows multiple modes of light to propagate through the fiber. As multiple modes of light
propagate through the fiber, they travel different distances depending on the entry angles. This
causes them to arrive at the destination at different times (a phenomenon called modal dispersion).
As a result, single-mode fiber is capable of higher bandwidth and greater cable run distances than
Distance
(Meters)
60
30
15
7.6
3.7
2.6
Distance (Meters)
1250
625
312
156
78
31
23
15
15
12
8
Site Requirements
Preparing for Installation 2-9