2-9
Cisco 2600 Series Routers Hardware Installation Guide
OL-2171-02
Chapter 2 Preparing to Install the Router
Preparing to Connect to a Network
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232 signals. The
recommended distance limits for EIA/TIA-449 shown in
Table 2-3
are also valid for V.35, X.21, and
EIA-530. Typically, EIA/TIA-449 and EIA-530 can support 2-Mbps rates, and V.35 can support 4-Mbps
rates.
Asynchronous/Synchronous Serial Module Baud Rates
The following baud-rate limitations apply to the slow-speed serial interfaces found in the
asynchronous/synchronous serial modules:
•
Asynchronous interface—Maximum baud rate is 115.2 kbps.
•
Synchronous interface—Maximum baud rate is 128-kbps full duplex.
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 2-1
.) 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.
Figure 2-1
EIA/TIA-232 Adapter Cable Connectors, Network End
EIA/TIA-449 Connections
EIA/TIA-449, which supports balanced (EIA/TIA-422) and unbalanced (EIA/TIA-423) transmissions,
is a faster version of EIA/TIA-232 (up to 2 Mbps) that provides more functions and supports
transmissions over greater distances.
Table 2-3
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
H1343a
DTE
DCE