Overview

Port Adapter Overview

PA-MC-2T3+ Multi-Channel T3 Overview

T3 Specifications

LEDs

Cables and Connectors

Overview

This chapter describes the multi-channel T3 port adapter (PA-MC-2T3+) and contains the following sections:

The PA-MC-2T3+ is a single-width port adapter that provides two T3 interface connections using BNC connectors. (See Figure 1-1.) The interface can provide up to 28 T1 lines (a single T3 group). Each T1 line is presented to the system as a serial interface that can be configured as one or more serial interfaces.

Figure 1-1: PA-MC-2T3+---Front Panel

The PA-MC-2T3+ has the following features and physical characteristics:

The PA-MC-2T3+ is a channelized port adapter.

It transmits and receives data bidirectionally at the T3 rate of 44.736 Mbps (digital signal carried on a T3 line, digital signal level 3 [DS3]).

The T3 connection, provided by two female BNC connections for transmit (TX) and receive (RX), requires 734A coaxial cable that has an impedance of 75 ohms.

It supports RFC 1406 and RFC 1407 (CISCO-RFC-1407-CAPABILITY.my). For RFC 1406, Cisco supports all tables except the "FarEnd" table. For RFC 1407, Cisco does not support "FarEnd" or "Fractional" tables. (For information on accessing Cisco MIB files, refer to the Cisco MIB User Quick Reference publication.)
On the VIP2, PA-MC-2T3+ microcode is loaded into and operates from synchronous dynamic random-access memory (SDRAM) on the VIP2-50.

PA-MC-2T3+ Multi-Channel T3 Overview

The PA-MC-2T3+ T3 links are channelized into 28 DS1 data lines. Each DS1 line can be unchannelized or channelized for serial transmission of data.

Each of the T1 lines can use the whole T1 bandwidth, a portion of the T1 bandwidth, or use the T1 bandwidth in channelized form for data transmission. Usable bandwidths for each T1 line are n x 56 kbps or n x 64 kbps, where n is a number representing timeslots 1 to 24. Channelized T1 allows up to 24 timeslots (56 kbps/64 kbps) per T1 line. The unused portion of the T1 bandwidth, when not running at full T1 speeds, cannot be used and is filled with idle channel data. Aggregation of multiple T1 lines is not supported. Further, the PA-MC-2T3+ can support a maximum of 256 logical channels.

Note T1 lines on the PA-MC-2T3+ are numbered 1-28, rather than the more traditional zero-based scheme (0-27) used with other Cisco products. This is to ensure consistency with telco numbering schemes for T1 lines within channelized (multi-channel) T3 equipment.

The T3 section of the PA-MC-2T3+ supports the maintenance data link channel (when using c-bit parity) as well as payload and network loopbacks. The T1 section of the PA-MC-2T3+ supports facilities data link (FDL) in extended super frame (ESF) framing, as well as various loopbacks. Bit error rate testing (BERT) is supported on each of the T1 lines. BER testing is typically done over an unframed T1 signal.

The PA-MC-2T3+ supports Cisco HDLC, Frame Relay, PPP, and SMDS Data Exchange Interface (DXI) encapsulations over each T1 link.

Note The PA-MC-2T3+ does not support the aggregation of multiple T1 lines (called inverse multiplexing or bonding) for higher bandwidth data rates.

The physical T3 link on the PA-MC-2T3+ consists of two female BNC connectors, one for receive (RX) and one for transmit (TX). You must use 75-ohm 734A coaxial interface cables with male BNC connectors to connect the PA-MC-2T3+'s interface with external T3 equipment. (For cable information, refer to the "Cables and Connectors" section.)

Any of the 28 T1 lines can be configured as channelized T1 lines. You can group the timeslots in these T1 lines into several individual logical channel groups, each of which carries data with different data link layer protocol encapsulations.

Each logical channel group can be composed of individual 56-kbps or 64-kbps timeslots, or individual timeslots plus ranges of timeslots; for example, timeslots 1, 9, and 12-14. Each logical channel group can contain from 1 to 24 timeslots maximum; the same time slot cannot be used in more than one logical channel group. Any unused timeslots are filled with programmable idle-channel data.

Each T1 line contains onboard T1 bit error rate test (BERT) circuitry. With this, the port adapter software can send and detect programmable patterns, and you can run a BERT test on one T1 line at a time per T3.

Note Onboard T3 BER testing is not supported.

T3 Specifications

The PA-MC-2T3+ T3 port is designed to receive and transmit at the DSX-3 level while driving and receiving from a 75-ohm coaxial cable (ATT 734A type coax). The T3 port connects directly to any equipment with DSX-3 level BNC connectors.

Table 1-1 lists the specifications that the T3 front end is designed to meet.

Parameter	Specification
Line rate	44.736 Mbps (±20 ppm)
Line code	B3ZS (bipolar with three-zero substitution)
Impedance	75 ohms
Pulse shape	ANSI T1.102, pulse amplitude is between 0.36 and 0.85 volts (V) peak
Input signal	DSX-3 (9.7 dB to -11.8 dB)
Output signal	DSX-3, able to drive 450 feet (135 meters) of 75-ohm coaxial cable (734A or equivalent) and meet pulse shape template at the line side

Table 1-1: Specification for the T3 Front End

Parameter Specification

Line rate

44.736 Mbps (±20 ppm)

Line code

B3ZS (bipolar with three-zero substitution)

Impedance

75 ohms

Pulse shape

ANSI T1.102, pulse amplitude is between 0.36 and 0.85 volts (V) peak

Input signal

DSX-3 (9.7 dB to -11.8 dB)

Output signal

DSX-3, able to drive 450 feet (135 meters) of 75-ohm coaxial cable (734A or equivalent) and meet pulse shape template at the line side

LEDs

The PA-MC-2T3+ has seven status LEDs located on its faceplate: ENABLED, ALARM, LOOP, LOS, OOF, AIS, and FERF. (These status LEDs are shown from left to right in Figure 1-2.)

Figure 1-2: PA-MC-2T3+ Status LEDs (Partial Horizontal View)

After system initialization, the green ENABLED LED indicates that the port adapter is enabled for operation.

The following conditions must be met before the PA-MC-2T3+ is enabled:

The port adapter is correctly connected to the VIP2 motherboard and both are receiving power.
The system bus recognizes the PA-MC-2T3+

If either one of the preceding conditions is not met, or if the initialization fails for other reasons, the ENABLED LED does not go on.

The six additional yellow status LEDs on the PA-MC-2T3+ indicate the following:

ALARM---This LED goes on when an alarm condition is received on any configured T1 line or the T3 link. Alarms on unconfigured T1 lines are not included.

: The alarms include T1 loss of frame (LOF), T1 alarm indication signal (AIS), T1 yellow alarm indication, T3 loss of signal (LOS), T3 AIS, and a T3 far-end receive failure (FERF) yellow alarm.
: This LED also blinks momentarily during port adapter initialization. If the blinking continues for an extended time, it indicates a port adapter boot failure.

LOOP---This LED goes on to indicate that a T1 line or the T3 link is in a loopback state and is therefore not enabled for normal data traffic.
LOS---This LED goes on when an LOS alarm occurs and is detected by the line interface unit (LIU) on the port adapter. This signal indicates a loss of the received signal on the T3 link. (This LED operates in conjunction with the ALARM LED.)
OOF---This LED goes on to indicate a DS3 out-of-frame (OOF) condition.
AIS---This LED goes on when an alarm indication signal is received on the T3 link. (This LED operates in conjunction with the ALARM LED.)
FERF--- This LED goes on when the receiver detects a FERF signal from the far end. When the OOF LED is on, the FERF LED indicates the port adapter state prior to the out-of-frame condition; that is, it reflects the last known state of the far-end receiver. When the OOF LED is off, the FERF LED reflects the live state of the far-end receiver.

Note In addition to the interface status information provided by the LEDs, you can also retrieve detailed interface status information either through the router console port or through Telnet or Simple Network Management Protocol (SNMP).

Cables and Connectors

The interface connectors on the PA-MC-2T3+ are 734A or equivalent coaxial BNC types, with one connector and cable for transmit (TX) and one for receive (RX). The BNC connectors are transformer-coupled to the PA-MC-2T3+ line interface unit (LIU), which is the analog physical interface on the PA-MC-2T3+.

The pinout and signal descriptions for the BNC connectors on the PA-MC-2T3+ are as follows:

Transmit (TX)---Transmitted signals appear on the center contact, and the outer shield is grounded for the 75-ohm 734A coaxial cable you attach to the TX BNC connector.
Receive (RX)---Received signals appear on the center contact, and the outer shield is grounded for the 75-ohm 734A coaxial cable you attach to the RX BNC connector.

Caution To prevent problems, you must check your 75-ohm 734A coaxial cable specifications when long cable lengths are required to connect the PA-MC-2T3+ to your external DS3 (T3) equipment. See Table 1-1 for cable length requirements.

Figure 1-3 shows the typical 75-ohm 734A coaxial cable pair that you supply and should use with the PA-MC-2T3+. Use only this type of coaxial cable pair for your PA-MC-2T3+ connections. Use one 75-ohm coaxial cable for each PA-MC-2T3+ connection: RX and TX.

Figure 1-3: 75-Ohm 734A Coaxial Cable Pair

Table of Contents

Overview

Overview

Port Adapter Overview

PA-MC-2T3+ Multi-Channel T3 Overview

T3 Specifications

LEDs

Cables and Connectors