Table of Contents

Processor and Trunk Cards

This chapter describes the hardware and functionality of the processor and trunk cards. It also describes the backplane and system bus. The description of each card includes:

• Function
  
  
• System interconnect
  
  
• Faceplate indicators
  
  

For all matters relating to installation, troubleshooting, user-commands, and repair and replacement, refer to the Cisco IGX  8400 Series Installation manual.

Other manuals that relate to IGX operation are:

• The Cisco WAN Switching Command Reference and Cisco WAN Switching SuperUser Command Reference describe standard user-commands and superuser-commands.
  
  
• The Cisco WAN Switching System Overview contains Cisco WAN Switching system and network information.
  
  
• The Cisco StrataView Plus Operations manual contains information on Cisco WAN Switching network management.
  
  

Processor, Trunk, and Alarm Card Types

Table 3-1 lists the front processor cards and the Alarm Module that can operate in the IGX switch. Table 3-2 lists the trunk cards. Table 3-3 lists the corresponding back cards. In addition, the IGX switch may use Adapter Card Modules (ACMs) to connect existing IPX 16/32 service modules and perform the adaptation that allows IPX 16/32 front cards to operate in an IGX node. (IPX 8-specific cards do not apply to the upgrade scheme.)

Common Alarms, Controls, and Indicators

Front cards and back cards have faceplates with indicator LEDs and, on some front cards, push-button controls. In addition, back card faceplates have the cable connectors. In slots where no back card exists, a blank faceplate must reside to contain Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) and to ensure correct air flow.

The LED indicators are on the front and back card faceplates. Each plug-in card has both a green ACTIVE LED and a red FAIL LED at the bottom of the faceplate. In general, the meaning of each LED is indicated in Table 3-4. Some other cards have additional indicators, connectors, or controls, which the appropriate sections describe.

Processor Cards

The processor card group consists of the Nodal Processor Module (NPM) and the System Clock Module (SCM). In conjunction with the system bus, the processor group is responsible for system timing, network control, and status reporting.

Nodal Processor Module (NPM)

The Nodal Processor Module (NPM) is a microprocessor-based system controller that runs the software for controlling the IGX. The NPM communicates with the other system cards over the control bus. Figure 3-1 illustrates the relation of the NPM to other parts of the system. The NPM performs the following major functions:

• Runs the software for controlling, configuring, diagnosing, and monitoring the IGX
  
  
• Sends configuration and control commands over the control bus to other cards in the node
  
  
• Receives statistics, status, and alarm messages from the other cards in the node
  
  
• Generates all system bus control signals for directing the interpretation of address buses and controlling data transfers
  
  
• Communicates with other nodes in the network
  
  

The NPM communicates with all other nodes through a trunk that uses a reserved data link at about 600 packets per second (pps). The NPM communication link with other nodes carries information about new connections, topology changes, and rerouting.

One version of the NPM exists for the NPM-32 and two versions of the NPM exist for the NPM-64. They are the NPM-32, NPM-64, and NPM-64B. In addition, the B versions use +5 VDC flash memory. Both versions of the NPM can reside in the same node if the resident software version supports the NPM-B version. The next section, titled "NPM Processor and Memory Capacity ," describes NPM memory.

NPM Processor and Memory Capacity

The DRAM memory in an NPM holds the switch software for performing the regular functions of the NPM. The NPMs also have memory features that let you download new software releases over the network and maintain the system software and its configuration if the power fails. Non-volatile flash EEPROM supports software downloading over the network. Battery-backup RAM (BRAM) stores system configuration data. Table 3-5 shows the basic memory capacities of each NPM.

NPM Redundancy

An IGX has one NPM in a non-redundant system or two NPMs in a redundant system. In a non-redundant system, an NPM resides in either front slot 1 or front slot 2. For a redundant system, NPMs reside in slots 1 and 2. The NPM plugs into the system bus backplane. A utility bus in the backplane connects the NPMs in a redundant system.

NPM Faceplate and LEDs

The faceplate of the NPM has a green ACTIVE LED and a red FAIL LED. See Figure 3-2 . The NPM monitors its own activity and, if a failure is detected, the FAIL LED is lit. If the node has redundant NPMs, the on-line NPM is indicated by the lit ACTIVE LED, while the standby NPM has no lit indicators. In addition to the status LEDs on the NPM faceplate, information on any NPM can be displayed at a terminal by executing the dspcd command.

System Clock Module (SCM)

The System Clock Module (SCM) card provides the main clock generation function for the IGX. It generates the system clock and trunk synchronizing clocks. The SCM phase-locks the internal IGX timing to the selected clock source for network synchronization. Each IGX node must have an SCM. The SCM plugs into back card slot 1.

SCM Features and Functions

The NPM and SCM card sets are the backbone of the IGX: without an NPM and SCM, the node is inoperative. The NPM controls and monitors the SCM control buses. A single SCM can support redundant NPMs.

In addition, the SCM provides:

• Two low-speed communications paths for a control terminal, a printer, or one or two modems
  
  
• One LAN communication path for connecting the Network Management System to the IGX
  
  

The SCM circuits include the following:

• Internal clock generator for the node
  
  
• Clock detection, alarm status, and control from the NPM
  
  
• Phase lock loops
  
  
• External clock input
  
  
• Clock, power supply, temperature, and fan monitoring
  
  
• Bus expansion
  
  
• Reset circuitry
  
  
• Control terminal, printer/modem, and LAN AUI ports
  
  
• 2 EIA/TIA-232 serial port interfaces
  
  
• 1 Ethernet port interface
  
  

The two serial EIA/TIA-232 ports provide connection to control terminals and modems for remote access to the node. In conjunction with the SCM, the NPM also supports a high-speed Ethernet LAN port for faster system statistics transfer between the node and a StrataView Plus NMS workstation. This port conforms to the requirements of IEEE standard 802.3 for Ethernet.

The SCM has duplicates of the internal clock circuitry and its associated phase lock loops and NPM-related control circuitry. One clock circuit operates off the System A Bus, and the other operates off the System B Bus. Both circuits operate independently and are monitored separately to provide complete backup if a circuit fails (which would cause the FAIL LED to turn on). However, because both the System A bus and System B bus clock circuits exist on a single card, removing the SCM disrupts system operation. The lower priority SCM circuits are not duplicated. The lower priority circuits are the external clock input, control and auxiliary ports, and monitoring circuits for power supplies, cabinet temperature, and fans. A failure in a lower priority circuit does not cause a system failure, but the SCM reports the problem.

The Ext Clock connector on the faceplate of the SCM provides an interface for an external source for a high-stability clock. This clock is configurable as the primary, secondary, or tertiary clock. The input is 1.544 MHz for T1 systems and 2.048 MHz for CEPT systems. In addition, one of the trunk or circuit line inputs may also serve as a source of timing for the node. If no clock source is selected, the clock source is the internal IGX clock.

Figure 3-3 and Table 3-6 describe the SCM faceplate connectors and LEDs. When you correlate the descriptions in the table with the callouts in the figure, read from the top to the bottom.

In addition to the clock functions, the SCM provides a pair of low-speed, serial communications ports. The CONTROL TERMINAL port is a bi-directional port for connecting the IGX to a local network control terminal or to a modem for remote terminal connection. The AUXILIARY PORT connects to a maintenance log printer, an additional dumb terminal, an alarm message collector, external device window, or an auto-dial modem for automatic reporting of local IGX alarm conditions. You can program the modem can to dial into Customer Service for assistance when a network alarm occurs.

Table 3-7 lists the pin assignments for the LAN connector.

Using the Power Supply Monitor Connector

The Power Supply Monitor (PSM) is an RJ-45 connector with the following pinout:.

• Pin 1 = Digital Ground
  
  
• Pin 2 = AACFAIL*_OUT
  
  
• Pin 3 = BACFAIL*_OUT
  
  

Each AC power supply provides an open collector output that goes low if an AC power failure occurs. The inactive state of the status signals is high on the SCM. The signals go into a ALS244 driver, the outputs of which are connected directly to the RJ-45 connector as well as circuitry that communicates the status to the control card.

To use the PSM connector, you need a device that responds with a fail condition when a "0" TTL logic level is present on pin 2 or pin 3.

Optional Alarm Interface Cards

The alarm relay card set is optional. The set consists of an Alarm Relay Module (ARM) front card and an Alarm Relay Interface (ARI) back card. This card set provides alarm summary outputs by using relay contact closures.

The alarm outputs are typically wired to a telephone central office alarm system for remote alarm reporting to give an indication there is a problem in the associated equipment.

The alarm summary feature provided by the Alarm Relay cards provides both a faceplate visual indication of an IGX node alarm as well as a set of relay outputs (dry-contact) for indicating node and network alarm indications. A visual alarm history indication is also provided. This alarm reporting is separate and is in addition to the alarm output at the node's control port, which provides a data output to a control terminal, such as the StrataView Plus Network Management Station. Table 3-8 summarizes the alarm conditions and the resulting indications.

One set of alarm relays is used to signal a major alarm or minor alarm on the node. One pair of contacts on each relay is used for audible alarms. These contacts are in series with a faceplate alarm cut-off (ACO) switch. The other set of relay contacts are used for visual alarms and are not affected by the ACO switch. When the ACO switch is activated, a faceplate ACO indicator lights up as a reminder to the operator. If the ACO switch is activated to disable the node's audible alarm output and a second alarm occurs, the audible alarm is re-activated. Two faceplate LEDs provide local indication of network alarms.

A second, independent, set of alarm outputs are provided to report network alarms. If a major or minor alarm occurs anywhere in the network—not necessarily on a particular node—these alarm relays are activated.

Major alarm relays are normally energized, providing an open circuit, so that a complete power failure (relay de-energized) at the node will result in a contact closure and resulting major alarm output. Minor alarms, however, are normally de-energized to conserve power and both contact closures as well as contact openings are available for minor alarms.

When an alarm condition clears, the alarm relays return to their normal state to clear the alarm outputs. A faceplate history indicator is turned on for each node alarm occurrence. The indicator will remain on even though an alarm may have already cleared. The history indicator is manually cleared by pressing a faceplate switch.

Two additional relays are available under software control to report other conditions, but these relays are currently unassigned.

The alarm reporting feature requires a card set that includes an ARM front card and an ARI back card. This card set can reside in any slot except the reserved slots. However, Cisco recommends that the front card go in the slot on the far right. Since a failure of either of these cards does not affect service, card redundancy is not necessary.

Alarm Relay Module (ARM)

The alarm relays are controlled by system software through Control Bus commands. The ARM interface with the Control Bus allows the card to receive alarm signals from the NPM and to send status signals back to the NPM. The firmware on the ARM decodes the alarms. The ARM does not connect to the Cellbus because it does not packetize user-data.

The ARM faceplate contains the alarm LEDs, ACO and History Clear push buttons, and the active and fail LEDs indicating the status of the ARM card (see Figure 3-4 and Table 3-9). The ARM card is used in conjunction with an ARI card. The ARI card connects to the ARM at the P2 connector. Relay drive signals originate in the ARM to operate relays on the ARI.

The ARM periodically runs a background self-test to determine the state of the card. If the card fails this self-test, the faceplate FAIL LED turns on, and the ACTIVE LED turns off.

Figure 3-4: ARM Faceplate

Table 3-9: ARM Faceplate Controls and Indicators

The installation of the ARM cards requires the removal of the node from service. The ARM can be physically installed in any front slot except slots normally reserved for the node processor cards (NPMs). For standardization, Cisco recommends that the ARM reside in the slot at the far right side of the card cage. The corresponding back slot must have an ARI card. The ARI card plugs directly in the ARM card.

User-Commands

Three commands affect the ARM card set:

• addalmslot
  
  
• delalmslot
  
  
• dspcd
  
  

Alarm Relay Interface Description (ARI)

The Alarm Relay Interface (ARI) card contains the alarm relays and their associated relay drivers. Alarm outputs are dry contact closures or opening contacts from Form C relays. The user must supply the voltage source to be switched by the IGX. Any source or load can be switched as long as it meets the following requirements.

• Voltage source, max. 220 Volts
  
  
• Steady-state current, max. 0.75 Amps
  
  
• Power dissipation, max. 60 Watts
  
  

A female DB37 connector resides on the faceplate for connection to the customer's office alarm or alarm-reporting system. Refer to Figure 3-5 for an illustration of the ARI faceplate.

Maintenance and Troubleshooting

The following paragraphs describe the maintenance and troubleshooting features associated with the ARM card set. Preventive maintenance is not necessary.

Card Self Test

Diagnostic routines periodically run to test the card's performance. These diagnostics run in the background and do not disrupt normal traffic. If a failure is detected during the self test, the faceplate red FAIL LED turns on. In addition, you can check the status of the card by using the Display Card (dspcd) command at the control terminal. If a card failure is reported, the report remains until cleared. To clear a card failure, use the Reset Card (resetcd) command.

Two types of resets are exist. They are hardware and failure. The reset failure clears the event log of any failure detected by the card self test and does not disrupt card operation. The hardware reset reboots the firmware and resets the card, which momentarily disables the card.

Card Replacement

ARM card set replacement is the same as other card replacement. For these procedures, refer to the repair and replacement description in the Cisco IGX 8400 Series Installation.

Adapter Cards

Cisco can upgrade StrataCom IPX service/interface cards for use in an IGX. This allows the IGX to provide all the services of the IPX with cards of proven efficiency, functionality, and reliability. The upgrade is available only as a factory upgrade. The factory upgrade consists of an adding one of three possible Adapter Card Modules (ACM) and possible firmware or hardware modifications. Due to the complexity of the ACM, field upgrades of IPX cards are not possible.

Connecting IPX front cards to their corresponding back cards on the IPX requires the use of a utility or local bus. On upgraded IPX cards (IGX cards), the local or utility bus is not necessary.

The following IPX cards can be adapted for use in the IGX:

• NTC
  
  
• AIT
  
  
• CDP
  
  
• FRP
  
  
• FTC
  
  
• SDP
  
  
• LDP
  
  
• ARC
  
  

Trunk Interface Cards

The IGX supports the following types of trunk cards:

• Network Trunk Module (NTM)
  
  
• Broadband Trunk Module (BTM)
  
  
• ATM Line Module B (ALM/B)
  
  

The NTM works with the following back cards:

• Back Card/T1 (BC-T1)
  
  
• Back Card/E1 (BC-E1)
  
  
• Back Card/Subrate (BC-SR)
  
  
• Back Card/Y1 (Japan) (BC-Y1)
  
  

The BTM works with the following back cards:

• T3 Back Card for BTM (AIT-T3)
  
  
• E3 Back Card for BTM (AIT-E3)
  
  
• E2 Back Card for BTM (AIT-E2)
  
  
• HSSI Back Card for BTM (AIT-HSSI)
  
  

The ALM/B works with the following back cards:

• Back Card/Universal ATM Interface T3 (BC-UAI-1T3)
  
  
• Back Card/Universal ATM Interface E3 (BC-UAI-1E3)
  
  

Trunk Card Maintenance

Trunk cards require no maintenance except for replacement after a confirmed failure. The tstcon command does not work on an AIT, BTM, or ALM/B because the card cannot be isolated from the BPX or other connecting ATM trunk.

Loopback Test

A trunk loopback test runs when an ATM trunk detects an integrated alarm. The loopback test indicates if the line or the card is faulty. A loopback test "pass" means the line is faulty, and a line alarm is indicated. A loopback test "fail" means the card is faulty. If the card is faulty, a switch occurs to an available Y-Cable equipped redundant card.

Network Trunk Module (NTM)

The Network Trunk Module (NTM) manages FastPacket transmission across a trunk line. NTM functions include the following:

• Receives FastPackets from the CELLBUS and queues them in separate queues for transmission on the selected trunk
  
  
• Arbitrates access to the trunk for the traffic type
  
  
• Monitors the age of each timestamped FastPacket, updates the timestamp for FastPackets at intermediate nodes, and discards FastPackets that exceed age limit
  
  
• Receives and checks FastPackets from the trunk and queues them for transmission to the System Bus
  
  
• Provides packet alignment based on the CRC in the FastPacket header
  
  
• Extracts clocking from the trunk that can be used as a clock source on the node or as a clock path
  
  
• Collects trunk usage statistics
  
  

An NTM can occupy any available front service card slot in the range 3 to 32. The choice of back card depends on the trunk interface type.

For fractional T1 trunk lines, the NTM and BC-T1 card set can provide the interface. Fractional trunk interfaces use a group of 64-Kbps channels, which constitute a partial T1 trunk. For example, a 512-Kbps fractional T1 trunk might use every third channel from 1 through 24. Fractional trunks use the basic trunk frequency (such as 1.544 Mbps for T1) for the clock rate. The network operator makes the channel assignments.

Fractional E1 is the same as fractional T1 except that the channels are 1 to 15 and 17 to 31 (0 and 16 reserved) and the clock rate is 2.048 Mbps).

The NTM supports subrate trunks if a BC-SR back card and appropriate local bus are present. Subrate trunks interface to the digital transmission facility at trunk rates in the range 256 Kbps through 2.048 Mbps. Three interface connections are provided. These are EIA/TIA-449, X.21, and V.35.

NTM and Back Card Redundancy

The NTM can be configured for 1:1 redundancy by using a second, identical, card group in an immediately adjacent slot, and a Y-cable for connection to the trunk. All of the back cards support redundancy.

NTM Status

The faceplate of the NTM has four LEDs. The first two in the following list apply to the NTM front card. Each of the other two LEDs is a summary alarm for the back card conditions. When lit, these LEDs have the following significance:

• The green ACTIVE LED indicates the NTM is active and functioning normally.
  
  
• The red FAIL LED indicates an NTM card failure was detected.
  
  
• The yellow MINOR LED indicates non-service-interrupting faults or when statistical errors have exceeded a preset threshold.
  
  
• The red MAJOR LED indicates a service-affecting failure was detected.
  
  

For more information on the significance of alarm LEDs, see the Cisco IGX 8400 SeriesInstallation publication.

The alarms and line conditions that the NTM monitors include those in the list that follows. To view errors on a trunk, use the dsptrkerrs command. To see a list of the (user-specified) errors that dsptrkerrs can display, use dsptrkstatcnf.

• E1 CRC4 errors
  
  
• T1 Bipolar violations
  
  
• Near end and far end frame alarms
  
  
• Alarm Information Signal (AIS)
  
  
• Loss of signal
  
  
• Line signal frame sync losses
  
  
• Packet out of frame
  
  

T1 Interface Card (BC-T1)

The T1 Trunk Interface Card (BC-T1) card terminates a single 1.544 Mbps T1 trunk line on the NTM. The BC-T1 can reside in any rear slot 3-8 in an IGX 8410, 3-16 of the IGX 8420, or 3-32 of the IGX 8430. The BC-T1 connects directly to the NTM.

The BC-T1 provides the following:

• Trunk line interfaces to T1 trunks at 1.544 Mbps
  
  
• Software selectable AMI or B8ZS (bipolar 8 zero suppress) line code
  
  
• Software selectable D4 or ESF (extended super-frame) framing format
  
  
• Configuration as either full or fractional T1 service
  
  
• Extraction of receive-timing from the input signal for use as the node timing
  
  
• Software selectable line buildout for cable lengths up to 655 feet
  
  
• Passes line event information to the front card
  
  

B8ZS supports clear channel operation because B8ZS eliminates the possibility of a long string of 0s. B8ZS is preferable whenever available, especially on trunks.

The BC-T1 supports two clock modes. The clock modes are normal clocking and loop timing. You select the mode through software control. With normal clocking, the node uses the receive clock from the network for the incoming data and supplies the transmit clock for outgoing data. The node can use the receive clock to synchronize itself with the network.

With loop timing, the node uses the receive clock from the network for the incoming data and redirects this receive clock to time the transmit data.

BC-T1 Faceplate Description

Figure 3-6 and Table 3-10 provide information on the faceplate of the BC-T1. When you correlate the descriptions in the table with the callouts in the figure, read from the top of the table to the bottom. The standard port connector is a female DB15.

E1 Interface Back Card (BC-E1)

The E1 Trunk Interface Card (BC-E1) provides an E1 trunk interface for the Network Trunk Module (NTM). The BC-E1 connects directly to the NTM and can reside in any rear slot 3-8 in an IGX 8410, 3-16 in an IGX 8420, or 3-32 in an IGX 8430. The BC-E1 provides the following:

• Interfaces to CEPT E1 lines (CCITT G.703 specification)
  
  
• Support for both Channel Associated Signalling and Common Channel Signalling
  
  
• Support for unframed 32 channel (2.048 Mbps), framed 31 (1.984 Mbps), or 30 (1.920 Mbps) channel operation, or any n x 64 Kbps rate down to 256 Kbps
  
  
• Configuration of either full or fractional E1 lines
  
  
• CRC-4 error checking
  
  
• Support for HDB3 (clear channel operation on E1 lines) or AMI
  
  
• Passes E1 line events (Frame loss, Loss of signal, BPV, frame errors, CRC errors, CRC synchronization loss, etc.) to the front card
  
  
• Detection of loss of packet sync when used with the NTM
  
  
• 120-ohm balanced or 75-ohm balanced or unbalanced physical interfaces
  
  

The BC-E1 supports two clock modes. The clock modes are normal clocking and loop timing. You select the mode through software control. With normal clocking, the node uses the receive clock from the network for the incoming data and supplies the transmit clock for outgoing data. The node can use the receive clock to synchronize itself with the network.

With loop timing, the node uses the receive clock from the network for the incoming data and redirects this receive clock to time the transmit data.

Statistics are kept on most line errors and fault conditions, including the following:

• Loss of signal
  
  
• Frame sync loss
  
  
• Multi-frame sync loss
  
  
• CRC errors
  
  
• Frame slips
  
  
• Bipolar violations
  
  
• Frame bit errors
  
  
• AIS, all-1's in channel 16 (CAS mode)
  
  

Figure 3-7 shows and Table 3-11 lists status LEDs and connections on the BC-E1 faceplate. When you correlate the table and figure items, read from the top to the bottom.

Subrate Interface Card (BC-SR)

The Back Card/Subrate (BC-SR) terminates subrate trunks on the NTM. A subrate trunk uses part of the E1 or T1 bandwidth. The BC-SR typically functions in tail circuits or where little traffic exists.

A subrate trunk facility interface operates in DCE mode, and the subrate channel functions like a synchronous data channel. Therefore, the IGX BC-SR always operates in DTE mode. Only leased lines are supported (no dial-up lines). Subrate trunks cannot pass clock signals between nodes.The BC-SR provides the following:

• Trunk line interfaces to subrate trunks
  
  
• Trunk rates of: 256 Kbps, 384 Kbps, 512 Kbps, 768 Kbps, 1.024 Mbps, 1.536 Mbps, 1.920 Mbps
  
  
• V.11/X.21, V.35, and RS-449 interfaces
  
  
• Synchronization of the trunk clocking with looped clock option (not applicable to X.21)
  
  
• A limited set of EIA control leads monitored by the system
  
  

Figure 3-8 and Table 3-12 describe the BC-SR faceplate. When you correlate the figure and table, read from the top down.

Table 3-13 lists the data signals and EIA leads supported by the subrate interface.

Figure 3-8: BC-SR Faceplate

Table 3-12: BC-SR Connections and Status LEDs

Y1 Interface Back Card (BC-Y1)

The BC-Y1 back card provides a Japanese Y1 trunk interface for an NTM. The BC-Y1 can reside in any rear slot 3-8 in an IGX 8410, 3-16 in an IGX 8420, or 3-32 in an IGX 8430. The BC-Y1 provides:

• An interface to Japanese "Y" Trunk (Y1) lines
  
  
• Support for Y1 Trunk formatted signalling
  
  
• Support for 24 channel, 1.544 Mbps operation
  
  
• Support for fractional rates
  
  
• Coded Mark Inversion (CMI) line coding
  
  
• Statistics for Y1 line events (loss of framing, loss of signal, framing errors, etc.)
  
  
• Support for local and remote loopback at the Y1 interface as well as the local bus interface for fault isolation.
  
  

The BC-Y1 supports two clock modes. These are normal clocking and loop timing. The system operator selects the mode through software control. Normal clocking uses the receive clock from the network for incoming data and supplies the transmit clock for outgoing data. This clock can be used to synchronize the node.

Loop timing uses the receive clock from the network for the incoming data and turns the receive clock around for timing the transmit data.

Figure 3-9 and Table 3-14 provide descriptions of the BC-Y1 status LEDs and connections on the faceplate. When you correlate the items in the figure and table, read from the top to the bottom.

Broadband Trunk Module (BTM)

The BTM card set provides an Asynchronous Transfer Mode (ATM) trunk interface. With a BTM, the IGX can use the standard ATM cell relay protocol on a T3 or E3 line. However, the BTM has a maximum throughput of 16 Mbps. Therefore, its typical use is to have multiple T1 or E1 channels up to a maximum of 8 channels. The BTM's compatibility with T3/E3 trunks supports migration towards T3/E3 rates in T1/E1 increments. In addition, the BTM supports optional E2 and HSSI interfaces to T3 or E3 lines. The maximum E2 rate is 8 Mbps. A HSSI back card supports a rate of 50.84 Mbps, so a BTM with a HSSI can burst at a rate up to 50.84 Mbps. Note that the use of a HSSI interface requires an external, inverse multiplexer that serves as a DCE and provides clocking.

The BTM card set consists of the BTM front card and either an AIT-T3, AIT-E3, AIT-E2, or AIT-HSSI back card. The card set works in the following arrangements:

• IGX-to-IGX (BTM-to-BTM)
  
  
• IGX-to-BPX communication over broadband ATM trunks (BNI)
  
  
• IGX-to-IPX (BTM on the IGX to AIT on the IPX)
  
  
• IGX frame relay connections terminating on an AXIS (complex gateway)
  
  

Operating Modes

The BTM/AIT card set can operate in either simple gateway or complex gateway mode. For a description of tiered networks, trunks, ATM protocols, and cell and header formats, refer to the Cisco WAN Switching System Overview publication.

The simple gateway loads 24-byte FastPacket cells into ATM cells in ways that are consistent with each application. (Each of the two FastPackets loaded into the ATM cell is loaded in its entirety, including the FastPacket header). For example, two FastPackets can go into one ATM cell if both FastPackets have the same destination.

Complex gateway is supported by streaming the frame relay data into ATM cells, cell after cell, until the frame has been completely transmitted. Since only the data from the FastPacket is loaded, the Complex gateway is an efficient transmission mechanism. Additionally, discard eligibility information carried by the frame relay bit is mapped to the ATM cell CLP bit, and vice versa.

LED Indicators and Alarms

The faceplate of the BTM has four LEDs. The ACTIVE LED indicates the card is active and functioning. A BTM card failure triggers the FAIL LED. The other two LEDs are a summary alarm for the AIT back card conditions. A yellow MINOR LED indicates either a fault that does not interrupt service or that error statistics have exceeded a preset threshold. A red MAJOR LED indicates a service-affecting failure. See Figure 3-10 .

Maintenance and Troubleshooting

The BTM card set requires no maintenance. If a card has a solid or a (confirmed) intermittent failure, replace it. The only indicators on the BTM faceplate are the ACTIVE and FAIL LEDs. For purposes of troubleshooting, you should view the BTM/AIT card set as a trunk. The tstcon command does not work on a BTM because the card cannot be isolated from the IGX or the other, connected BTM.

A trunk loopback test runs when the BTM detects an integrated alarm. The loopback test verifies if the line or the card is faulty. A loopback test "pass" means that the line is faulty, and a line alarm is indicated. A loopback test "fail" means that the card is faulty. In the case of a faulty card, a switch to a Y-Cable equipped redundant card occurs if available.

Descriptions of BTM Back Cards

A back card provides the interface to the trunk line and performs all CRC generation and checking. Its faceplate has six LEDs to indicate alarm conditions and the port status. The BTM back cards are:

• AIT-T3, which has a single T3 port (maximum throughput 16 Mbps)
  
  
• AIT-E3, which has a single E3 port (maximum throughput 16 Mbps)
  
  
• AIT-E2, which has a single E2 port
  
  
• AIT-HSSI, which carries aggregated T1 lines on a single connector
  
  

AIT-T3 Back Card

The AIT -T3 back card has two BNC connectors and six LED indicators, as Figure 3-11 shows. Table 3-15 lists these faceplate items. When you correlate the items in the figure and table, read from the top.

AIT-HSSI Back Card

The AIT-HSSI back card supplies a single HSSI interface to the AIT trunk. For its implementation, the AIT-HSSI requires an external DSU such as an inverse mux or a fractional T3 DSU. Figure 3-12 shows the faceplate of the AIT-HSSI. The HSSI connector has 50 pins.

The range of bit rates for the AIT-HSSI on a BTM is 4 Mbps to 16 Mbps. The range of rates is across aggregated T1 channels. The command that configures the rate is cnftrk. The dsptrkcnf command displays the existing parameters for a trunk. For specifications on HSSI, refer to the appendix titled "System Specifications."

AIT-E2 Back Card

The AIT-E2 back card supplies a single E2 interface to the 16-Mbps BTM front card. The line rate is 8.448 Mbps. The AIT-E2 operates between only StrataCom nodes, so it does not support a UNI interface. For specifications on this E2 line, refer to the appendix titled, "System Specifications." Figure 3-13 shows the AIT-E2 faceplate.

Y-Cable Redundancy

The BTM card set supports Y-cable redundancy on ATM trunks in IGX-to-IGX, IGX-to-IPX and IGX-to-BPX applications. Y-cable redundancy is an IGX feature that you can apply to ATM trunks. (In the Cisco WAN Switching Command Reference, see commands addyred, delyred, dspyred, and ptyred.) Before you assign Y-cable redundancy, you must have upped (uptrk) and added (addtrk) the trunks on both cards.

Y-Cable Redundancy Switching

The BTM performs a clock test on the input line source. If either the clock or the card fails, a switchover occurs to a Y-cabled, redundant BTM trunk card set if one is available. If the switchover occurs, the primary ATM trunk card acquires failed status, and the red FAIL indicator turns on. If Y-cable redundancy is not available, the ATM trunk switches to another clock source and marks the line as a failed clock source.

ATM Line Module B (ALM/B)

The ATM Line Module B (ALM/B) card set provides a trunk with a full T3 or E3 rate. Back cards for the ALM/B are the BC-UAI-1T3 and the BC-UAI-1E3. They support either a single T3 trunk or a single E3 trunk. For characteristics of T3 and E3 trunks, refer to the appendix titled "System Specifications." For information on how to bring up an ALM/B trunk, refer to the Cisco IGX 8400 Series Installation publication. Figure 3-14 illustrates an ATM cloud using the ALM/B.

ALM/B Features

The ALM/B supports the following:

• An aggregate throughput of 45 Mbps
  
  
• STI or NNI cell header format
  
  
• Buffer capacity of 65535 cells
  
  
• Support for all connection classes
  
  
• 1771 complex gateway (CGW) connections
  
  
• Optional Y-cable redundancy
  
  

The ALM/B card set consists of the ALM/B front card and either a BC-UAI-1T3 or a BC-UAI-1E3. The card set works in the following arrangements:

• IGX-to-IGX (ALM/B-to-ALM/B or ALM/B-to-BTM)
  
  
• IGX-to-BPX communication over broadband ATM trunks (BNI)
  
  
• IGX-to-IPX (ALM/B on the IGX to AIT on the IPX)
  
  
• IGX frame relay connections terminating on an AXIS (complex gateway)
  
  

Operating Modes

On a per-connection basis, the ALM/B operates in either simple gateway or complex gateway mode. Complex gateway supports network interworking. For a description of tiered networks, trunks, ATM protocols, and cell and header formats, refer to the Cisco WAN Switching System Overview publication.

The simple gateway loads 24-byte FastPacket cells into ATM cells in ways that are consistent with each application. (Each of the two FastPackets loaded into the ATM cell is loaded in its entirety, including the FastPacket header). For example, two FastPackets can be loaded into one ATM cell if both FastPackets have the same destination.

Complex gateway is supported by streaming the frame relay data into ATM cells, cell after cell, until the frame has been completely transmitted. Since only the data from the FastPacket is loaded, the Complex gateway is an efficient transmission mechanism. Additionally, discard eligibility information carried by the frame relay bit is mapped to the ATM cell CLP bit, and vice versa.

Maintenance and Troubleshooting

The ALM/B card set requires no maintenance. If an ALM/B card set has either a solid or an intermittent but confirmed failure, replace it. The only indicators on the ALM/B faceplate are the ACTIVE and FAIL LEDs. For purposes of troubleshooting, you should view the ALM/B card set as a trunk. The tstcon command does not work on an ALM/B because the card cannot be isolated from the IGX or the other, connected trunk card set.

A trunk loopback test executes when the ALM/B detects an integrated alarm. The loopback test determines if the line or the card is faulty. A loopback test "pass" means the line is faulty, so a line alarm is flagged. A loopback test "fail" means the card is faulty. If a card is faulty and a Y-cabled secondary is available, a switch to the secondary card occurs.

LED Indicators and Alarms

The faceplate of the ALM/B has four LEDs. See Figure 3-15 .The ACTIVE LED indicates the card is active and functioning. An ALM/B card failure triggers the FAIL LED. The other two LEDs are a summary alarm for the back card conditions. A yellow MINOR LED indicates either a fault that does not interrupt service or that error statistics have exceeded a preset threshold. A red MAJOR LED indicates a service-affecting failure.

Y-Cable Redundancy

The ALM/B card set supports Y-cable redundancy on ATM trunks in IGX to IGX, IGX to IPX and IGX to BPX applications. (In the Cisco WAN Switching Command Reference, see descriptions of addyred, delyred, dspyred, and ptyred.)

Y-cable redundancy requires that the trunks on both cards are upped (uptrk) and added (addtrk) before you assign redundancy with the addyred command.

Switchover to a Redundant ALM/B

The ALM/B performs a clock test on the input line source. If either the clock or the card fails, a switchover occurs to a Y-cabled, redundant ALM/B trunk card set if one is available. If the switchover occurs, the primary ATM trunk card acquires failed status, and the red FAIL indicator turns on. If Y-cable redundancy is not available, the ATM trunk switches to another clock source and marks the line as a failed clock source.

Interface Back Cards for the ALM/B

The back card provides the interface to the trunk line and performs all necessary CRC generation and checking. The following are the ALM/B back cards:

• Back Card/Universal ATM Interface T3 (BC-UAI-1T3)
  
  
• Back Card/Universal ATM Interface E3 (BC-UAI-1E3)
  
  

The trunk ports consist of one BNC connector for transmit data and one BNC connector for receive data. The back card faceplate has six LED indicators. The LEDs indicate the status of the port and various alarm conditions. See Figure 3-16 and Table 3-16 for details on the T3 card and Figure 3-17 and Table 3-17 for details on the E3 card. Correlate items in each figure and table as you read from the top down. For technical specifications on T3 and E3 lines, see the appendix titled "System Specifications."

Figure 3-16: BC-UAI-1T3 Faceplate

Table 3-16: BC-UAI-1T3 Connections and Indicators

Figure 3-17: BC-UAI-1E3 Faceplate

Table 3-17: BC-UAI-1E3 Connections and Indicators