2-30 Cisco 4000 Series Hardware Installation and Maintenance
Network Connection Considerations
The specifications for the BRI cable are given in Table 2-6.
Table 2-6 BRI Cable Specifications
Note The multiport BRI network processor module requires that all its interfaces connect to the
same carrier or from carriers with synchronized master clocks. If the BRI module connects to ISDN
interfaces which have an unsynchronized master clock, the module’s interfaces will occasionally
lose some packets.
Channelized T1 Connections
The Cisco 4000 series router supports a channelized T1 (CT1) network processor module with one
T1 interface.The CT1 provides one channelized T1 connection via a serial cable to a channel service
unit (CSU). On the CT1, the controller provides up to 24 virtual channels. Each virtual channel is
presented to the system as a serial interface that can be configured individually. This interface is the
physical media that supports ISDN PRI.
The CT1, shown in Figure 2-32, provides a controller for transmitting and receiving data
bidirectionally at the T1 rate of 1.544 Mbps. For wide-area networking, the CT1 can function as a
concentrator for a remote site.
Parameter High-Capacitance Cable Low-Capacitance Cable
Resistance (@ 96 kHz
1
)
1. kHz = kilohertz.
160 ohms/km 160 ohms/km
Capacitance (@ 1 kHz) 120 nF/km
2
2. nF = nanoFarad.
30 nF/km
Impedance (@ 96 kHz) 75 ohms 150 ohms
Wire diameter 0.024" (0.6 mm) 0.024" (0.6 mm)
Distance limitation 32.8' (10 m) 32.8' (10 m)
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