Overview

This chapter describes the PA-4B-U synchronous serial port adapter (PA-4B-U[=]) and contains the following sections:

The PA-4B-U, shown in Figure 1-1, provides up to four U-type BRI interfaces for connecting Cisco 7100 series and Cisco 7200 series routers to an ISDN WAN through its internal network terminator (NT1) device. Each PA-4B-U interface consists of two bearer (B) channels that can transmit and receive data at the rate of 64-kilobits per second (kbps) or 56 kbps, full duplex, and one data (D) channel that can transmit and receive data at the rate of 16 kbps, full duplex. The B channels are used for transmitting user data. The D channel is used for call setup control and network connection teardown, and provides the communication from the router to the ISDN switch. The PA-4B-U supports dial-on-demand routing (DDR).

Each PA-4B-U interface is an RJ-45 receptacle. A standard straight-through twisted pair cable is available from Cisco Systems and other vendors for use with the PA-4B-U.

Note Cisco 7200 series and Cisco 7100 series routers support the online insertion and removal (OIR) of all port adapter types.

Figure 1-1: PA-4B-U Port Adapter---Faceplate View

The PA-4B-U can be installed in any of the available port adapter slots in Cisco 7200 or Cisco 7100 series routers. Figure 1-2 shows a PA-4B-U installed in port adapter slot 1 of a Cisco 7206.

Figure 1-2: Cisco 7206 with a PA-4B-U Port Adapter in Port Adapter Slot 1

LEDs

The PA-4B-U has an enabled LED, standard on all port adapters, and three status LEDs for each port. (See Figure 1-3.)

Figure 1-3: LEDs on the PA-4B-U Port Adapter---Horizontal Orientation

After system initialization, the enabled LED goes on to indicate that the port adapter has been enabled for operation.

The following conditions must be met before the PA-4B-U is enabled:

The port adapter is correctly connected to the midplane and receiving power.
A valid system software image for the port adapter has been downloaded successfully.
The system recognizes the port adapter.

If any of the above conditions are not met, or if the initialization fails for other reasons, the enabled LED will not go on. Table 1-1 lists port LED status indications.

Port LED	Status
NT1	This green LED comes on and remains on when the integrated NT1 device is connected to an ISDN switch.
B1	This green LED comes on when there is data traffic on channel B1.
B2	This green LED comes on when there is data traffic on channel B2.

Table 1-1: PA-4B-U Port LEDs

Port LED Status

NT1

This green LED comes on and remains on when the integrated NT1 device is connected to an ISDN switch.

B1

This green LED comes on when there is data traffic on channel B1.

B2

This green LED comes on when there is data traffic on channel B2.

Cables and Pinouts

The four U-type BRI interfaces on the PA-4B-U support a standard, straight-through twisted pair cable with an RJ-45 connector at the router (Cisco 7200 series) end and at the network end. Cisco Systems does not provide the cable; it is widely available from other vendors. Figure 1-4 shows the PA-4B-U interface cable.

Figure 1-4: PA-4B-U Interface Cable

Table 1-2 lists the pinouts for the PA-4B-U interface cable.

NT ¹RJ-45 8-Pin² Connector	Wire	LT³ RJ-45 8-Pin² Connector
4	Signal⁴	4
5	Signal	5

Table 1-2: PA-4B-U Interface Cable Pinouts

NT ¹RJ-45 8-Pin² Connector Wire LT³ RJ-45 8-Pin² Connector

4

Signal⁴

4

5

Signal

5

¹NT refers to the network terminating layer 1 aspects of NT1 and NT2 functional groups.
² Pins 1, 2, 3, 6, 7, and 8 are not used.
³ LT refers to the line termination point (for example, at the wall jack).
⁴Signal represents Tip or Ring.

Table of Contents

Overview

Overview

Port Adapter Overview

LEDs

Cables and Pinouts