BRI Connections

The BRI network processor module (see Figure 4-25) supports four BRI ports. Each BRI port is an RJ-45 8-pin connector. Use an appropriate cable to connect the BRI module directly to an ISDN through an ISDN CSU/DSU called the NT1. The common carrier will provide the NT1 connection, except in North America, where the NT1 is owned by the customer.

Figure 4-25 Four-Port BRI Network Processor Module Ports

The specifications for the BRI cable are given in Table 4-9.

Table 4-9 BRI Cable Specifications

Parameter	High-Capacitance Cable	Low-Capacitance Cable
Resistance (@ 96 kHz(1))	160 ohms/km	160 ohms/km
Capacitance (@ 1 kHz)	120 nF(2)/km	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)

(1)

kHz = kilohertz.

(2)

nF = nanoFarad.

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All the interfaces on the multiport BRI network processor module must connect to the same carrier or to carriers with synchronized master clocks. If the BRI module connects to ISDN interfaces that have an unsynchronized master clock, the module's interfaces will occasionally lose some packets.

Making BRI Connections

Using the appropriate cable, connect the BRI port to the ISDN through the NT1. The common carrier will provide the NT1 connection worldwide, except in North America, where the NT1 is owned by the customer. The NT1 is an ISDN CSU/DSU.

Warning Network hazardous voltages are present in the BRI cable. If you detach the BRI cable, detach the end away from the router first to avoid possible electric shock. Network hazardous voltages also are present on the system card in the area of the BRI port (RJ-45 connector), regardless of when power is turned off. To see translated versions of this warning, refer to the appendix "Translated Safety Warnings."

The BRI network processor module supports pointtopoint operation at Layer 1 of the Open System Interconnection (OSI) reference model. Only one source (the transmitter) and one sink (the receiver) are actively transmitting at any time in each direction at an S interface (CCITT specification I.430 section 3.1). The BRI module does not support a pointtomultipoint wiring configuration. Because the BRI module does not support pointtomultipoint configuration, D-channel access procedures are not implemented.

BRI Pinout

The BRI interface port pinout is shown in Table 4-10.

Table 4-10 BRI Port Pinout (RJ-45)

8 Pin(1)	TE(2)	NT(3)	Polarity
3	Transmit	Receive	+
4	Receive	Transmit	+
5	Receive	Transmit	--
6	Transmit	Receive	--

(1)

Pins 1, 2, 7, and 8 are not used.

(2)

TE refers to terminal terminating layer 1 aspects of TE1, TA, and NT2 functional groups.

(3)

NT refers to network terminating layer 1 aspects of NT1 and NT2 functional groups.

Caution To prevent damage to the system, make certain you connect the BRI cable to the BRI connector only and not to any other RJ-45 connector.

Testing the BRI Interface

Take the following steps to construct an external loopback RJ-45 connector, which is useful for isolating hardware problems on an individual BRI port:

Step 1 Connect pin 3 to pin 4. (See Figure 4-25.)

Step 2 Connect pin 5 to pin 6.

Step 3 Connect a 50-ohm resistor across pin 3 and pin 5.

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Pins 1, 2, 7, and 8 are not connected.

With the loopback RJ-45 connector plug installed in a BRI port, use the test interface command to verify that the hardware is functioning correctly.

Powering Up the Router

Caution Never operate the router unless the unit is completely closed to ensures adequate cooling.

Take the following steps to power up the router:

Step 1 Plug the system power cord into a 3-terminal, single-phase power source that provides power within the acceptable range (200W, 85 to 264 VAC, 50 to 60 Hz).

Warning This product relies on the building's installation for short-circuit (overcurrent) protection. Ensure that a fuse or circuit breaker no larger than 120 VAC, 15A U.S. (240 VAC, 10A international) is used on the phase conductors (all current-carrying conductors). To see translated versions of this warning, refer to the appendix "Translated Safety Warnings."

Step 2 Turn ON the system power switch. The LED labeled POWER on the front panel should go on.

Step 3 Verify that the OK LED on the right side of the front panel goes ON after a few seconds delay.