Table of Contents

Overview

This chapter describes the 6T3 line card and contains the following sections:

Line Card Overview

The 6T3 line card provides a full-duplex operation at T3 (45 Mbps) speed. It supports both 16- and 32-bit cyclic redundancy checks (CRCs); the default is 16-bit CRC. You can change the default setting with software commands.

The 6-port 6T3 line card, shown in Figure 1-1, provides up to 24 network interfaces per Cisco 7304 router.

Features

The 6T3 line card provides the following features:

Interoperability Guidelines for 6T3 Line Card DSUs

The 6T3 line card supports several types of integrated data service units (DSUs). Table 1-1 lists the feature compatibilities of 6T3 line card DSUs.

Maintenance Data Link Messages

T3 maintenance data link (MDL) messages are used to communicate identification information between local and remote ports. The type of information included in MDL messages includes the equipment identification code (EIC), location identification code (LIC), frame identification code (FIC), unit, Path Facility Identification (PFI), port number, and Generator Identification numbers. The values for each piece of MDL message identification can be defined only by a network administrator and are discussed in ANSI T1.107.

For information on transporting MDL messages between source and destination T3 ports on a Cisco 7304 router, refer to T3 Maintenance Data Link Messages on the Cisco 7304 Router .

LEDs

The 6-port 6T3 line card has six LNK LEDs, one for each port, as well as one OIR LED and one STATUS LED. (See Figure 1-2.)

After system initialization, the STATUS LED goes on to indicate that power is received and that the 6T3 line card is enabled for operation.

The following conditions must all be met before the 6T3 line card is enabled:

If any one of these conditions is not met, or if the initialization fails, the STATUS LED does not go on.

Table 1-2 lists 6T3 line card LED colors and indications.

T3 SMB Cables

The cables used to connect the 6T3 line card are presented in the following sections:

We recommend using six T3 SMB cables. The cables are 10 feet (3.048 meters) long and have two female SMB connectors on one end, and two female or male bayonet coupling (BNC) connectors on the other end. Use the female SMB cable connectors to connect the local line card RX and TX ports. Use the BNC cable connectors to connect the line card RX and TX ports to other devices. See Figure 3-2.

Note   Cisco does not automatically provide the six T3 SMB cables recommended for your 6T3 line card.

Note   Electromagnetic compliance (EMC) was verified with the 10-foot (3.048 meters) shielded cables that are orderable through Cisco. We recommend that you use only the 10-foot (3.048 meters) shielded T3 SMB cables; otherwise, EMC is not guaranteed. If you use cables other than those ordered from Cisco, it is your responsibility to ensure that you have a compliant system that meets local EMC requirements. To order additional cables, use the product numbers: 2CBLE-SMB-BNC-M (male) and 2CBLE-SMB-BNC-F (female).

Note   When you connect the 10-foot (3.048 meters) shielded T3 SMB cables to the 6T3 line card, be careful not to bend the male cable connector pin when you connect or disconnect the cables. Observe the receive (RX) and transmit (TX) cabling relationship shown in Figure 1-4.

After you connect the cables to a configured port on the line card, it takes up to 35 seconds to initialize the line card and light the green LNK LED.

Ordering Cables

You must order cables separately with the 6T3 line card when you order a Cisco 7304 router. Cables are not automatically included with the 6T3 line card. Be sure to specify the type of cable you want shipped with your card (2CBLE-SMB-BNC-M [male] or 2CBLE-SMB-BNC-F [female]).

Building Your Own Cables

You can build your own cables for the 6T3 line card by using the cable components listed in Table 1-3. All three cables have an SMB connector at one end to connect to the 6T3 line card. The two SMB-to-BNC cables in Table 1-3 differ only in that one terminates in a male BNC connector, while the other terminates in a female BNC connector. You can use the back-to-back cable for directly connecting two closely-spaced 6T3 line cards back-to-back. These cables should be shielded and have SMB connectors on both ends.

Note   Back-to-back configurations, (6T3 line card serial-to-6T3 line card serial port configurations) require a specially built SMB-to-SMB cable. Table 1-3 provides cable connector specifications. Or you can use the 2CBLE-SMB-BNC-M 10-foot (3.048 meters) shielded cable and the 2CBLE-SMB-BNC-F 10-foot (3.048 meters) shielded cable connected together.

You can order the SMB-to-BNC cables from Cisco as product numbers 2CBLE-SMB-BNC-F (female) or 2CBLE-SMB-BNC-M (male) BNC terminations, respectively. Cisco does not sell the SMB-to-SMB cable.

Caution   Cisco assumes no responsibility for system operation with other than Cisco-supplied adapter cables. The customer is responsible for ensuring that any customer-built cables meet all of the applicable compliance requirements (see the "Related Documentation" section).

T3 systems are designed for cable lengths of 450 feet (137 meters) between the transmitter and the DSX-3 demarcation point where the standard pulse mask must be met. From the DSX-3 point, another run of 450 feet (137 meters) is allowed to the receiver, making a total of 900 feet (274 meters) between transmitter and receiver. This limitation is due to signal attenuation in the cable.

Although the American National Standards Institute (ANSI) standard T1.404-1994 stipulates the Western Electric or equivalent 728A SMB cable, it has been replaced by the Lucent (formerly AT&T) 734A cable. Cisco tested more than 900 feet (274 meters) of 734A SMB cable from transmitter to receiver including the SMB-to-BNC adapter cables to verify high signal attenuation.

Table 1-4 lists some approximate attenuation values from the ANSI standard, and shows the RG-179 attenuation. RG-179 has a much higher attenuation, so take this information into account if you plan long runs of RG-179 cable.

Management Information Base

Management Information Base (MIB) attributes are readable and writable across Integrated Local Management Interface (ILMI) through use of the Simple Network Management Protocol (SNMP).

The 6-port 6T3 line card supports the DS3 interface MIB (RFC 1407).

Line Card Slot Locations on the Supported Platform

This section discusses line card slot locations on the supported platform. The illustration that follows summarizes slot location conventions on the Cisco 7304 router:

Cisco 7304 Router Slot Numbering

Figure 1-5 shows a Cisco 7304 with the network services engine (NSE) installed in slots 0 and 1 and line cards installed in slots 2 through 4. In the Cisco 7304, slot 0 is in the lower left position, and slot 5 is in the upper right position.

Identifying Interface Addresses

This section describes how to identify interface addresses for the 6T3 line card in the Cisco 7304 router. Interface addresses specify the actual physical location of each interface on a router or switch.

Interfaces on the 6T3 line card installed in a router maintain the same address regardless of whether other line cards are installed or removed. However, when you move a line card to a different slot, the first number in the interface address changes to reflect the new slot number.

Table 1-5 explains how to identify interface addresses.

Cisco 7304 Router Interface Addresses

This section describes how to identify the interface addresses used for the 6T3 line card in the Cisco 7304 router. The interface address is composed of a two-part number in the format slot-number/interface-port-number. See Table 1-5 for the interface address format.

In the Cisco 7304 router, slots are numbered from the lower left to the upper right, beginning with slot 0 and continuing through slot 5. (Slot 0 and slot 1 are reserved for the NSE.)

The interface address of the interfaces on a 6-port 6T3 line card in slot 2 are 2/0 through 2/5 (slot 2 and interfaces 0 through 5). If the 6T3 line card was in slot 4, these same interfaces would be numbered 4/0 through 4/5 (slot 4 and interfaces 0 through 5).