2-12
Cisco 3700 Series Routers Hardware Installation Guide
OL-2180-07
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 Data Rates
The following data-rate limitations apply to the slow-speed serial interfaces found in the
asynchronous/synchronous serial modules:
•
Asynchronous interface—Maximum data rate is 115.2 kbps.
•
Synchronous interface—Maximum data rate is 128-kbps full duplex.
ISDN BRI Connections
The BRI WAN interface cards provide Integrated Services Digital Network (ISDN) Basic Rate Interface
(BRI) connections. The BRI modules and BRI WAN interface cards are available with either an S/T
interface that requires an external Network Termination 1 (NT1), or a U interface that has a built-in NT1.
You can install the BRI modules in any available slot in the chassis.
Warning
Hazardous network voltages are present in WAN ports regardless of whether power to the unit is OFF
or ON. To avoid electric shock, use caution when working near WAN ports. When detaching cables,
detach the end away from the unit first.
Statement
1026
Use a BRI cable (not included) to connect the BRI WAN interface card directly to an ISDN.
Table 2-4
lists the specifications for ISDN BRI cables. See the
Cisco Modular Access Router Cable Specifications
online document for pinouts. This document is available on Cisco.com.
Table 2-3
Serial Signal Transmission Speeds and Distances
Rate (bps)
EIA/TIA-232
Distance
EIA/TIA-449, X.21, V.35,
EIA-530 Distance
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
