Cisco Systems OL-3560-02 User Manual

Overview

This chapter describes the PA-4T port adapter and contains the following sections:

• Port Adapter Overview, page 1-1

• Synchronous Serial Overview, page 1-2

• LEDs, page 1-3

• Cables, Connectors, and Pinouts, page 1-4

• Port Adapter Slot Locations on the Supported Platforms, page 1-13

• Identifying Interface Addresses, page 1-15

Port Adapter Overview

The PA-4T, shown in Figure 1-1, provides four channel-independent, synchronous serial ports that support full-duplex operation at T1 (1.544 Mbps) and E1 (2.048 Mbps) speeds. Each port supports any of the available interface types: Electronics Industries Association/Telecommunications Industries Association (EIA/TIA)-232, EIA/TIA-449, V.35, X.21, and EIA-530. The cable attached to each PA-4T interface port determines its type (EIA/TIA-232, and so forth) and its mode (DCE or DTE).

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Note Although the VIP supports online insertion and removal (OIR), individual port adapters do not. To

replace port adapters, you must first remove the VIP from the chassis, and then replace port adapters as required.

Cisco 7200 series routers support OIR of all port adapter types.

Figure 1-1 PA-4T—Faceplate View

PA-4T Synchronous Serial Port Adapter Installation and Configuration

FAST SERIAL

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Synchronous Serial Overview

The PA-4T supports the following interface types: EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA-530. EIA/TIA-232, which is by far the most common interface standard in the United States, supports unbalanced circuits at signal speeds up to 64 kbps. EIA/TIA-449, which supports balanced (EIA/TIA-422) and unbalanced (EIA/TIA-423) transmissions, is a faster (up to 2 Mbps) version of EIA/TIA-232 that provides more functions and supports transmissions over greater distances. The EIA/TIA-449 standard was intended to replace EIA/TIA-232, but it was not widely adopted.

Note The EIA/TIA standards were referred to as recommended standards called RS-232 and RS-449 prior to

their acceptance by the ANSI committee.

The resistance to convert to EIA/TIA-449 was due primarily to the large installed base of DB-25 hardware and to the larger size of the 37-pin EIA/TIA-449 connectors, which limited the number of connections possible (fewer than are possible with the smaller, 25-pin EIA/TIA-232 connector).

EIA-530, which supports balanced transmission, provides the increased functionality, speed, and distance of EIA/TIA-449 on the smaller,DB-25connectorusedfor EIA/TIA-232. The EIA-530 standard was created to support the more sophisticated circuitry of EIA/TIA-449 on the large number of existing EIA/TIA-232 (DB-25) hardware instead of the larger, 37-pin connectors used for EIA/TIA-449. Like EIA/TIA-449, EIA-530 refers to the electrical specifications of EIA/TIA-422 and EIA/TIA-423. The specification recommends a maximum speed of 2 Mbps. EIA-530 is used primarily in the United States.

The V.35 interface is most commonly used in the United States and throughout Europe, and is recommended for speeds up to 48 kbps. The X.21 interface uses a 15-pin connection for balanced circuits and is commonly used in the United Kingdom to connect public data networks. X.21 relocates some of the logic functions to the DTE and DCE interfaces and, as a result, requires fewer circuits and a smaller connector than EIA/TIA-232.

All interface types except EIA-530 can be individually configured for operation with either external (DTE mode) or internal (DCE mode) timing signals; EIA-530 operates with external timing only. In addition, all VIP serial interface types support non-return to zero (NRZ) and non-return to zero inverted (NRZI) format, and both 16-bit and 32-bit cyclic redundancy checks (CRCs). The default configuration is for NRZ format and 16-bit CRC. You can change the default settings with software commands. (For more information, see Chapter 4, “Configuring the PA-4T.”)

There is no default mode or clock rate set on the VIP serial ports, although an internal clock signal is present on all ports for DCE support. Using the internal clock, you can also perform local loopback tests without having to terminate the port or connect a cable. (All interface types except X.21 DTE support loopback.) To use the port as a DCE interface, you must set the clock rate and connect a DCE adapter cable. Touse the port as a DTE interface, you need only connect a DTE adapter cable to the port. Because the serial adapter cables determine the mode and interface type, the PA-4T interface becomes a DTE when a DTE cable is connected to it.

If a DTE cable is connected to a port with a clock rate set, the DTE ignores the clock rate and uses the external clock signal that is sent from the remote DCE.

For a brief description of the clock rate command, see Chapter 4, “Configuring the PA-4T.” For complete command descriptions and instructions, see the publications listed in the “Related

Documentation” section on page vi.

Chapter 1 Overview

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PA-4T Synchronous Serial Port Adapter Installation and Configuration

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Chapter 1 Overview

Synchronous Serial Specifications

The PA-4T provides up to four synchronous serial interfaces. Each interface allows a maximum bandwidth of 2.048 Mbps; the speed depends on the type of electrical interface used. Use EIA/TIA-232 for speeds of 64 kilobits per second (kbps) and below, and use X.21, EIA/TIA-449, V.35, or EIA-530 for higher speeds.

Serial signals can travel a limited distance at any given bit rate; generally, the slower the baud rate, the greater the distance. All serial signals are subject to distance limits beyond which a signal degrades significantly or is completely lost.

Table 1-1 lists the recommended (standard) maximum speeds and distances for each PA-4T serial

interface type. The recommended maximum rate for V.35 is 2,048 Mbps.

Table 1-1 Standards for Transmission Speed Versus Distance

Synchronous Serial Specifications

LEDs

EIA/TIA-232 Distances

Rate (bps) Feet Meters Feet Meters

EIA/TIA-449, X.21, V.35, EIA-530 Distances

2400 200 60 4,100 1,250 4800 100 30 2,050 625 9600 50 15 1,025 312 19200 25 7.6 513 156 38400 12 3.7 256 78 56000 8.6 2.6 102 31 1544000 (T1) – – 50 15

Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232. The recommended distance limits for EIA/TIA-449 shown in Table 1-1 are also valid for V.35, X.21, and EIA-530. EIA/TIA-449 and EIA-530 support 2.048-Mbps rates, and V.35 supports 2.048-Mbps rates without any problems; we do not recommend exceeding published specifications for transmission speed versus distance. Do so at your own risk.

The PA-4Tcontains the enabled LED, standard on all port adapters, and a one status LED for each port. After system initialization, the enabled LED goes on to indicate that the PA-4T has been enabled for operation. The LEDs are shown in Figure 1-2.

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Figure 1-2 LEDs on the PA-4T—Horizontal Orientation Shown

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Cables, Connectors, and Pinouts

The green enabled LED on the port adapter indicates that the motherboard is enabled and receiving power, and that the port adapter is ready for operation.

The following conditions must be met before the enabled LED goes on:

• The PA-4T interface is correctly connected and receiving power

• The PA-4T-equipped card or router contains a valid microcode version that has been downloaded

successfully

• The bus recognizes the PA-4T or PA-4T-equipped VIP

If any of these conditions is not met, or if the initialization fails for other reasons, the enabled LED does not go on.

Table 1-2 lists LED colors and indications.

Table 1-2 PA-4T LEDs

Chapter 1 Overview

DTE

LED Label

TD Transmit

TC Transmit

RD Receive

RC Receive

LB/CD – – Green: DTR, DSR, RTS, CTS, or DCD active

EN (enable) – – Green: port adapter enabled

Function

data out

clock in

data in

clock in

DCE Function Color and Function

Transmit data in

Transmit clock in (TXCE)

Receive data out

Receive clock out

Green

Yellow: local loop or internal loop active

Cables, Connectors, and Pinouts

The following sections describe the serial receptacles on the PA-4T, and the cables and pinouts for the various serial interface cables.

PA-4T Port Adapter Receptacles and Cables

The PA-4T and adapter cables allow a high density of interface ports, regardless of the size of the connectors typically used with each electrical interface type. All ports use an identical 60-pin, D-shell receptacle that supports all interface types: EIA/TIA-232, V.35, EIA/TIA-449, X.21, and EIA-530. Each port requires a serial adapter cable, which provides the interface between the high-density serial port and the standard connectors that are commonly used for each electrical interface type.

Note The adapter cable determines the electrical interface type and mode of the port (DTE or DCE) to which

it is connected.

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Chapter 1 Overview

Cables, Connectors, and Pinouts

The network end of the cable is an industry-standard connector for the type of electrical interface that the cable supports. For most interface types, the adapter cable for DTE mode uses a plug at the network end, and the cable for DCE mode uses a receptacle at the network end. Exceptions are V.35 adapter cables, which are available with either a V.35 plug or a receptacle for either mode, and the EIA-530 adapter cable, which is available only in DTE mode with a DB-25 plug at the network end. The mode is labeled on the molded plastic connector shell at the ends of all cables except V.35 (which uses the standard Winchester block-type connector instead of a molded plastic D-shell).

Followingare the available interface cable options (and product numbers) for the mode and network-end connectors for each cable:

• EIA/TIA-232: DTE mode with a DB-25 plug (CAB-232MT=); DCE mode with a DB-25 receptacle

(CAB-232FC=)

• EIA/TIA-449: DTE mode with a 37-pin D-shell plug (CAB-449MT=); DCE mode with a 37-pin

D-shell receptacle (CAB-449C=)

• V.35: DTE mode or DCE mode with a 34-pin Winchester-type V.35 plug (CAB-V35MT= or

CAB-V35MC=); DTE mode or DCE mode with a 34-pin Winchester-type V.35 receptacle (CAB-V35FT= or CAB-V35FC=). Also available is a cable with a male DB-60 plug on the router end and a male DB-34 shielded plug on the network end (CAB-V35MTS=).

• X.21: DTE mode with a DB-15 plug (CAB-X21MT=); DCE mode with a DB-25 receptacle

(CAB-X21FC=)

• EIA-530: DTE mode with a DB-25 plug (CAB-530MT=)

Note For cable pinouts, refer to the “Cables, Connectors, and Pinouts” section on page 1-4.

Figure 1-3 shows the serial port adapter cables for connection from the PA-4T your network.

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