Cisco CISCO2650 - 2650 Router Hardware Installation Manual page 105

Chapter 5 Connecting Serial Network Modules
All serial interface types except EIA/TIA-530 and EIA/TIA-530A are available in DTE or DCE format:
DTE with a plug connector at the network end, and DCE with a receptacle at the network end. V.35 is
available in either mode, with either gender at the network end. EIA/TIA-530 and EIA/TIA-530A are
available in DTE only.
Serial cables are not provided with the network module. For ordering information, see the
Technical Assistance" section on page
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 Cable Specifications. For further information, see the
on page
About Data Rates and Distance Limitations
All serial signals are subject to distance limits, beyond which the signal degrades significantly or is
completely lost. Generally, the slower the data rate, the greater the distance.
Table 5-3
understand and compensate for potential electrical problems, you may get good results at speeds and
distances greater than those listed. For instance, the recommended maximum rate for V.35 is 2 Mbps,
but 4 Mbps is commonly used.
Table 5-3
Data Rate, bps
2400
4800
9600
19200
38400
56000
1544000 (T1)
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
EIA/TIA-530. Typically, EIA/TIA-449 and EIA/TIA-530 support 2-Mbps rates, and V.35 can support
4-Mbps rates.
Asynchronous and Synchronous Serial Module Data Rates
The following data-rate limitations apply to the slow-speed serial interfaces found on asynchronous and
synchronous serial modules:
•
•
OL-2485-20
viii.
lists recommended maximum speeds and distances for each serial interface type. If you
Serial Interface Recommended Maximum Speeds and Distances
EIA/TIA-232 Distance
Feet
200
100
50
25
12
9
—
The maximum data rate on the slow-speed asynchronous interface is 115.2 kbps. The traffic
throughput rate allowed is the full 115.2 kbps, with 10 percent of traffic in the opposite direction.
The maximum data rate for the slow-speed synchronous interface is 128 kbps full duplex.
xi.
EIA/TIA-449, -530, -530A, V.35, and X.21 Distance
Meters Feet
60 4100
30 2050
15 1025
8 500
4 250
3 100
— 50
Table 5-3
Cisco Network Modules Hardware Installation Guide
About Serial Connections
"Obtaining
"Obtaining Documentation" section
Meters
1250
625
312
150
75
30
15
are also valid for V.35, X.21, and
5-3