Table of Contents

Channelized T3 Interface Processor (CT3IP-50) Installation and Configuration

Product Numbers: CT3IP-50(=)

Introduction

This configuration note contains instructions for installing and configuring the Channelized T3 Interface Processor (CT3IP-50) in the Cisco 7000 series routers and the Cisco 7500 series routers. For the CT3IP-50 to operate properly in the Cisco 7000 series routers, the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) must be installed.

This configuration note also contains basic configuration steps and examples. For complete descriptions of additional interface subcommands and configuration options available for your router, refer to the appropriate configuration publications listed in the section "If You Need More Information" on page 2. (Refer to the section "CT3IP-50 Software and Hardware Prerequisites," on page 7, for specific compatibility requirements.)

Contents

Sections in this document include the following:

If You Need More Information

The Cisco IOS software running your router contains extensive features and functionality. For information on Cisco IOS software and for general installation and maintenance information for your router, use the following resources:

Cisco documentation and additional literature are available in a CD-ROM package, which ships with your product. The Documentation CD-ROM, a member of the Cisco Connection Family, is updated monthly; therefore, it might be more up to date than printed documentation. To order additional copies of the Documentation CD-ROM, contact your local sales representative or call customer service. The CD-ROM package is available as a single package or as an annual subscription.

What Is the CT3IP-50?

The CT3IP-50, shown in Figure 1 and Figure 2, is a fixed-configuration interface processor based on the second-generation Versatile Interface Processor (VIP2-50).

The CT3IP-50 has the following features and physical characteristics:

CT3IP-50 Memory Configurations

The following is the default shipping CT3IP-50 SDRAM and SRAM configuration: 4 MB of SRAM, 32 MB of SDRAM.

The following additional SDRAM and SRAM upgrade products are available:

T3 Overview

T3 traditionally involves multiplexing 28 T1 lines on to a single higher-speed line (T3 line). Each of the 28 T1 lines in the T3 are asynchronous to one other. A T1 line accommodates 24 64-kilobit-per-second (kbps) DS0 channels. While the DS0s are byte multiplexed to each T1, the T1 lines are bit multiplexed to the T3 in a framing format called M23 or c-bit parity.

M13 multiplexing is done in two steps. First, four T1 lines are bit multiplexed together to form a DS2 line using M12 multiplexing. These seven DS2 lines are then bit multiplexed together to form the DS3/T3 using M23 multiplexing.

M13 multiplexing uses bit stuffing to bring each asynchronous DS1/DS2 up to a common data rate for transmission. The function of c-bit parity multiplexing is to force the seven DS2s to be synchronous to each other at a rate that causes 100-percent pulse stuffing in the M23 frame, allowing the "stuff" indicator bits in the M23 frame to be used as a maintenance link between the end points.

CT3IP-50 Overview

The CT3IP-50 functions very much like an M13 multiplexer with each T1 line terminating with or originating into or from an HDLC controller on the port adapter. The CT3IP-50 offers 28 individual T1 channels (bundled in the T3) for serial transmission of data. Each of the T1 channels uses a portion of the T1 bandwidth (fractional T1) or the entire T1 bandwidth for data transmission. Usable bandwidths for each T1 are n x 56 kbps or n x 64 kbps, where n is a number from 1 to 24. The unused portion of the T1 bandwidth, when not running at full T1 speeds, cannot be used and is filled with idle channel data.

The T3 section of the CT3IP-50 supports the maintenance data link channel (c-bit parity) as well as payload and network loopbacks. The T1 section of the CT3IP-50 supports facilities data link (FDL) in extended super frame (ESF) framing, as well as network and payload loopbacks. Bit error rate testing (BERT) is supported on each of the T1 links. The BERT testing is only done over a framed T1 signal. The M13 multiplexer performs M12 multiplexing on 4 four T1 signals. (There are seven M12 multiplexers available on board.)

The seven M12 multiplexers pass their data to the M23 multiplexer, which takes the seven tributaries and formats them into a DS3 stream. This transmit stream is passed on to the T3 line interface unit (LIU) for transmission out of the BNC connector into a 75-ohm coaxial line. The first three T1 channels of the channelized T3 can be broken out, under software control, to the three DB-15 connectors on the front of the CT3IP-50 for further demultiplexing via a MultiChannel Interface Processor (MIP). This allows three (the first three) of the 28 T1 streams in the channelized T3 to be a channelized T1 stream.

The broken-out T1(s) are sent to a T1 LIU, which transmits the T1(s) at the DSX-1 level. (DSX-1 refers to the cross connection point for DS-1 signals.) When operating in this mode, these ports are not CSU ports. They do not detect loop codes, provide ones-density requirements, or respond to any FDL messages. The receiving end (MIP) must provide the CSU functionality. Under software control, each external T1 port can be disabled or enabled. The CT3IP-50 does not support the aggregation of multiple T1s (called inverse muxing or bonding) for higher bandwidth data rates. CT3IP-50 supports Cisco HDLC, Frame Relay, PPP, and SMDS Data Exchange Interface (DXI) encapsulations over each T1 link. For SMDS only, DXI is sent on the T1 line so it needs to connect to an SMDS switch that has direct DXI input.

There is a special DB-15 connector on the CT3IP-50, labeled TEST. This test connector allows you to break out any T1 of the T3 stream, under software control. This functionality allows you to break out any of the 28 T1s within the T3 stream for testing (for example, 24-hour BERT testing as is commonly done by telephone companies before a line is brought into service), or for further channelization via a MIP card.

CT3IP-50 Microcode

The CT3IP-50 microcode is a software image that provides card-specific software instructions. Cisco 7000 series and Cisco 7500 series routers support downloadable microcode, which enables you to upgrade microcode versions by downloading new microcode images, storing them in Flash memory, and instructing the system to load an image from Flash memory. You can store multiple images for an interface type and instruct the system to load any one of them with a configuration command. All interfaces of the same type (all CT3IP-50s, and so on) will load the same microcode image from a single image stored in Flash memory. The Flash-based boot read-only memory (ROM) device on the CT3IP-50 contains a microcode boot image that instructs the system to load the full microcode image as described by the configuration.

Although multiple microcode versions for a specific interface type can be stored concurrently in Flash memory, only one image can load at startup. The show controller cbus command displays the currently loaded and running microcode version for each interface processor. The show microcode command displays the microcode images bundled with the Cisco IOS software.

An example of the show microcode command follows:

In the preceding example, the CT3IP-50's microcode is listed as VIP2 because the CT3 port adapter is attached to a VIP2-50 motherboard and uses its microcode image. (For a complete description of microcode and downloading procedures, refer to the section "Upgrading Microcode" on page 42.)

CT3IP-50 Agency Compliance and Electrical Interface Specifications for T3 and T1

The T3 line interface unit (LIU) is designed to meet the following specifications:

The T3 LIU is compliant for the above specifications for input jitter tolerance, pulse shape/amplitude (DSX3), line termination, and jitter. The LIU has a flat transfer function so jitter introduced by the LIU is insignificant.

The CT3IP-50 T3 port is designed to receive and transmit at the DSX-3 level while driving and receiving from a 75-ohm coaxial cable (ATT 728A type coax). It connects directly to any equipment with DSX-3 level BNC connectors. The T3 front end is designed to meet the following specifications:

The T1 LIU is designed to meet the following specifications. (See also Table 1.)

The T1 LIU is designed to meet the preceding specifications for input jitter tolerance, pulse shape/amplitude (DSX1), line termination, and jitter. The LIU has a relatively flat transfer function so jitter introduced by the LIU is minimal.

The CT3IP-50 T1 ports are designed to receive and transmit at the DSX-1 level while driving and receiving from a 100-ohm twisted-pair cable. It connects directly to any equipment with DSX-1 level input/output. The T1 front end is designed to meet the following specifications:

Table 1  

T1 Channel Data Rates

CT3IP-50 Installation Prerequisites

Before you begin the installation, review the guidelines in this section to assure proper system operation, avoid injuring yourself, or damaging the equipment.

CT3IP-50 Software and Hardware Prerequisites

The Cisco IOS software recommended for use with a CT3IP-50 in a Cisco 7000 series or Cisco 7500 series router is Cisco IOS Release 11.1(14)CA or later.

For the CT3IP-50 to operate properly in the Cisco 7000 series routers, the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) must be installed. The CT3IP-50 will not operate properly in Cisco 7000 series routers with the Route Processor (RP) and Switch Processor (SP) (or Silicon Switch Processor [SSP]) installed.

The show version command displays the current hardware configuration of the router, including the system software version that is currently loaded and running. The show controller cbus command lists all electrical interfaces and includes the currently loaded and running microcode version for each.

If the displays indicate that the running system software is earlier than Cisco IOS Release 11.1(14)CA or later, check the contents of Flash memory to determine if the required images are available on your system. The show flash command displays a list of all files stored in Flash memory.

The show microcode command displays a list of all the microcode images currently bundled with the Cisco IOS software. If these displays indicate that the required system software and microcode are not available, contact a service representative for upgrade information. (Refer to the section "Upgrading Microcode," on page 42, for more information. For information on additional show commands, refer to the section "Command Descriptions and Examples" on page 28.)

CT3IP-50 Interface Cables

For T1, two standard serial cables, null-modem and straight-through, are available from Cisco Systems and other vendors for use with the CT3IP-50. The CT3IP-50 T1 interface cables are used to connect your router to external CSUs or a MIP card. The CT3IP-50 T1 interface cables have two male 15-pin DB connectors at each end to connect the CT3IP-50's T1 interfaces.

Figure 3 shows the CT3IP-50 interface cable, connectors, and pinouts. Table 2 lists the signal pinout for the straight-through cable. Table 3 lists the signal pinout for the null-modem cable.

Table 2   T1 Straight-Through Cable Signals

Table 3   T1 Null-Modem Cable Signals

Guidelines for Installing and Removing Processor Modules

The processor modules for the Cisco 7000 series and Cisco 7500 series slide into slots in the rear of the chassis and connect directly to the backplane. The backplane slots are keyed so that the processor modules can be installed only in the slots designated for them. Figure 4 shows the ejector levers and captive installation screws on a typical interface processor. To remove an interface processor, loosen the captive screws and pull the ejector levers to the sides; then pull the module out using the handle.

To insert an interface processor, reverse the process, making sure to firmly seat the interface processor in its connectors on the backplane. For detailed directions, refer to the procedures in "Removing a CT3IP-50," on page 14, and "Installing a New or Replacement CT3IP-50 and Connecting Interface Cables" on page 15.

Caution Always use the ejector levers to remove or install the CT3IP-50. The ejectors help ensure that backplane connectors on the card are fully seated in, or fully ejected from, the backplane. Failure to use the ejector levers could result in a partial backplane connection, which can hang the system or could damage the backplane.

Caution The CT3IP-50 is made up of two parts: a dual-width port adapter and a motherboard. To prevent problems with the CT3IP-50 and with the system in which the CT3IP-50 is installed, do not attempt to separate the CT3IP-50's port adapter from its motherboard. The entire CT3IP-50 assembly is a field replaceable unit (FRU).

The captive installation screws on the ends (see Figure 4) of each faceplate, when tightened, provide EMI shielding and also help ensure proper seating in the backplane. After using the ejector levers to install a CT3IP-50, tighten the captive installation screws to prevent the CT3IP-50 from becoming partially dislodged from the backplane. These screws must be tightened to meet EMI specifications.

List of Parts and Tools

You need the following parts and tools to install the CT3IP-50. If you need additional equipment, contact your service representative for ordering information.

Safety Guidelines

This section lists safety guidelines you should follow when working with any equipment that connects to electrical power or telephone wiring.

Electrical Equipment Guidelines

Follow these basic guidelines when working with any electrical equipment:

Telephone Wiring Guidelines

Use the following guidelines when working with any equipment that is connected to telephone wiring or to other network cabling:

Preventing Electrostatic Discharge Damage

Electrostatic discharge (ESD) damage, which can occur when electronic cards or components are improperly handled, results in complete or intermittent failures. The CT3IP-50 comprises a printed circuit board that is fixed in a metal carrier. Electromagnetic interference (EMI) shielding, connectors, and a handle are integral components of the carrier. Although the metal carrier helps to protect the board from ESD, use a preventive antistatic strap whenever handling the CT3IP-50. Handle the carriers by the handles and the carrier edges only; never touch the boards or connector pins.

Following are guidelines for preventing ESD damage:

Caution For safety, periodically check the resistance value of the antistatic strap. The measurement should be between 1 and 10 megohms.

CT3IP-50 Installation Procedures

The following sections describe the procedures for removing or installing a CT3IP-50 in a Cisco 7000 series or 7500 series router. The online insertion and removal feature allows you to install and remove a CT3IP-50 without turning off system power; however, you must follow the insertion instructions carefully. For example, failure to use the ejector levers or insert the CT3IP-50 properly can cause system error messages indicating a board failure.

The function of the ejector levers on the CT3IP-50 is to align and seat the card connectors in the backplane. Failure to use the ejectors and insert the interface processor properly can disrupt the order in which the pins make contact with the backplane. Follow the CT3IP-50 installation and removal instructions carefully, and review the following examples of incorrect insertion practices and results:

Use the ejector levers when removing a CT3IP-50 to ensure that the board connector pins disconnect from the backplane in the logical sequence expected by the system. Any RSP or interface processor that is only partially connected to the backplane can hang the bus. Detailed steps for correctly installing or removing a CT3IP-50 are included with the following procedures.

Caution To avoid erroneous failure messages, remove or insert only one interface processor at a time. Also, after inserting or removing an interface processor, allow at least 15 seconds before removing or inserting another interface processor so that the system can reinitialize and note the current configuration of all interfaces.

Removing a CT3IP-50

You need not shut down the interface or the system power when removing a CT3IP-50 or other interface processor.

If you have a Cisco 7507 or a Cisco 7513 with an RSP2 configured as the system slave, we strongly recommend that you use the following procedure to remove and replace an interface processor:

Step 2   Wait 15 seconds.

Step 3   Remove and replace the interface processor using the procedures in this publication.

Step 4   Wait 15 seconds.

Step 5   Reinsert the slave RSP2.

If you are replacing a failed CT3IP-50, remove the existing board first, then replace the new CT3IP-50 in the same slot. If you are replacing a currently installed interface processor with a CT3IP-50, remove the existing board first, then install the new CT3IP-50 in the same slot.

Figure 5 shows proper handling of an interface processor during installation.

Use the following procedure to remove the CT3IP-50:

Step 2   Loosen the captive installation screws at the top and bottom of the CT3IP-50. (See Figure 4a.)

Caution Always use the ejector levers to remove or install the CT3IP-50. Failure to do so can cause erroneous system error messages, indicating a board failure.

Step 3   Place your thumbs on the upper and lower ejector levers and simultaneously push the top ejector lever up and the bottom ejector lever down (in the opposite direction from that shown in Figure 4c) to release the CT3IP-50 from the backplane connector.

Step 4   Grasp the CT3IP-50 handle with one hand and place your other hand under the carrier to guide the CT3IP-50 out of the slot. (See Figure 4.) Avoid touching the board or any connector pins.

Step 5   Carefully pull the CT3IP-50 straight out of the slot, keeping one hand under the carrier to guide it. (See Figure 4.) Keep the CT3IP-50 parallel to the backplane.

Step 6   Place the removed CT3IP-50 on an antistatic mat or foam pad, or place it in an antistatic bag if you will return it to the factory.

Step 7   If the interface processor slot is to remain empty, install an interface processor filler
(MAS-7000BLANK=) to keep dust out of the chassis and to maintain proper airflow through the interface processor compartment.

Installing a New or Replacement CT3IP-50 and Connecting Interface Cables

The CT3IP-50 slides into any available interface processor slot and connects directly to the backplane. The backplane slots are keyed so that the CT3IP-50 can be installed only in an interface processor slot. Interface processor fillers, which are blank interface processor carriers, occupy empty slots to maintain consistent air flow through the interface processor compartment.

If you are installing a new CT3IP-50, you will have to first remove the interface processor filler from the available interface processor slot. Figure 4 shows the functional details of inserting an interface processor and using the ejector levers. Figure 5 shows proper handling of an interface processor during installation.

Caution Remove or insert only one interface processor at a time. Allow at least 15 seconds for the system to complete the preceding tasks before removing or inserting another interface processor. Disrupting the sequence before the system completes its verification can cause the system to interpret hardware failures.

Use the following procedure to install the CT3IP-50:

Step 2   Choose an available interface processor slot for the CT3IP-50, and ensure that the CT3IP-50 interface cable is of a sufficient length to connect the CT3IP-50 with the CSU.

Step 3   Interface processors and interface processor fillers are secured with two captive installation screws. (See Figure 4a.) Use a flat-blade screwdriver to loosen the captive installation screws and remove the interface processor filler (or the existing CT3IP-50) from the slot. If you remove the CT3IP-50, immediately place it into an antistatic bag to prevent damage from electrostatic discharge.

Step 4   Hold the CT3IP-50 handle with one hand, and place your other hand under the carrier to support the CT3IP-50 (see Figure 4) and guide it into the slot. Avoid touching the card or any connector pins.

Caution To prevent ESD damage, handle interface processors by the handles and carrier edges only.

Step 5   Place the back of the CT3IP-50 in the slot and align the notch on the bottom of the carrier with the groove in the slot. (See Figure 4a.)

Step 6   While keeping the CT3IP-50 parallel to the backplane, carefully slide the CT3IP-50 into the slot until the back of the faceplate makes contact with the ejector levers, then stop. (See Figure 4b.)

Caution Always use the ejector levers when installing or removing processor modules. A module that is partially seated in the backplane will cause the system to hang and subsequently crash.

Step 7   Using the thumb and forefinger of each hand to pinch each ejector lever, simultaneously push the top ejector lever down and the bottom ejector lever up until both are parallel to the faceplate. (See Figure 4c.)

Step 8   Tighten the captive screws on the interface processor faceplate to prevent the interface processor from becoming partially dislodged from the backplane and ensure proper EMI shielding. (These screws must be tightened to meet EMI specifications.)

Caution Always tighten the captive installation screws on each new interface processor before installing additional interface processors. These screws prevent accidental removal and ensure proper EMI protection for the system.

Step 9   Attach the CT3IP-50 network interface cables between the CT3IP-50 interface ports and the CSU. This includes up to four T1 cables and two DS1 BNC cables. (See Figure 6.) Proceed to the following section to check the cable connections.

This completes the procedure for installing a CT3IP-50 and attaching interface cables.

Using LEDs to Check CT3IP-50 Status

The CT3IP-50 has several status LEDs on its faceplate. (See Figure 7.)

Following are the functions of the CT3IP-50 LEDs:

For additional functions of the status and alarm LEDS, refer to the section "Using Status and Alarm LED Indications" on page 38.

The individual 1, 2, 3, and test LEDS next to each T1 port will go on when the respective port is enabled. When the port is not enabled, the green LED is off.

The remaining five LEDs, between the TEST and T3 ports, indicate the following:

Observe the LED states and the console displays as the router initializes. When the system has reinitialized all interfaces, the enabled LED on the CT3IP-50 should go on.

The console screen will also display a message as the system discovers each interface during its reinitialization. After system initialization, the enabled LED goes on to indicate that the CT3IP-50 is enabled for operation.

The following conditions must be met before the CT3IP-50 is enabled:

If any of these conditions is not met, the enabled LED does not go on.

Use the following procedure to verify that the CT3IP-50 is connected correctly:

Step 2   When the reinitialization is complete, verify that the enabled LED on the CT3IP-50 is on and remains on. If the LED does stay on, proceed to Step 5. If the enabled LED does not stay on, proceed to the next step.

Step 3   If the enabled LED on the CT3IP-50 fails to go on, suspect the that the CT3IP-50 board connector is not fully seated in the backplane. Loosen the captive installation screws, then firmly push the top ejector down while pushing the bottom ejector up until both are parallel to the CT3IP-50 faceplate. Tighten the captive installation screws. After the system reinitializes the interfaces, the enabled LED on the CT3IP-50 should go on. If the enabled LED goes on, proceed to Step 5. If the enabled LED does not go on, proceed to the next step.

Step 4   If the enabled LED still fails to go on, remove the CT3IP-50 and try installing it in another available interface processor slot.

Step 5   Use the show interfaces or show controllers cbus command to verify the status of the CT3IP-50's interfaces. (If the interfaces are not configured, you must use the procedures in the section "Configuring the CT3IP-50," which are not available until you configure them.)

If an error message displays on the console terminal, refer to the appropriate reference publication for error message definitions. If you experience other problems that you are unable to solve, contact a service representative for assistance.

Configuring the CT3IP-50

This section describes the procedures required to configure the T1 and T3 interfaces on a CT3IP-50. If you want to change the configuration of an interface, you must enter configuration mode. If you replaced the CT3IP-50 that was previously configured, the system will recognize the new CT3IP-50 and bring it up in the existing configuration.

After you verify that the new CT3IP-50 is installed correctly, use the privileged-level configure command to configure the new CT3IP-50 controller. Be prepared with the information you will need, such as the following:

For a complete summary of the configuration options available and more detailed instructions for configuring the CT3IP-50 controller, refer to the appropriate configuration publications, which are listed in the section "If You Need More Information," on page 2.

Using the EXEC Command Interpreter

Before you can use the configure command, you must enter the privileged level of the EXEC command interpreter with the enable command. The system will prompt you for a password if one has been set.

The system prompt for the privileged level ends with a pound sign (#) instead of an angle bracket (>). At the console terminal, enter the privileged level as follows:

Step 2   Enter the password (the password is case sensitive). For security purposes, the password is not displayed.

Step 3   When you enter the correct password, the system displays the privileged-mode system prompt (#) as follows:

Note To save your configuration changes to NVRAM, use the copy running-config startup-config command at the privileged-mode system prompt.

Proceed to the following sections to configure the CT3IP-50 controller.

Interface Port Numbering for T1 and T3

The interface numbering scheme for the CT3IP-50's T1 interfaces is in the form of slot/port-adapter/port:t1 channel: where slot refers to the chassis slot in which the CT3IP-50 is installed, port-adapter is always 0 (because the CT3IP-50 has only one dual-width port adapter); port refers to the physical port on the CT3IP-50 and is always 0; and t1 channel is a number between 1 and 28. (Refer to the section "Configuring the CT3IP-50," on page 20, for more specific interface configuration information.)

Designate and turn on an external T1 port (one of the three DB-15 connectors labeled 1 through 3) using the t1 external channel command, where t1 channel is a number between 1 and 3.

Designate and turn on the T1 test port (the DB-15 connector labeled TEST) using the t1 test channel command, where t1 channel is a number between 1 and 28.

Port Numbering Examples and Sample Displays

Following are examples of CT3IP-50 interface port numbering and sample displays:

The following sample display shows the events logged by the system as the CT3IP-50 was removed from slot 3; the system then reinitialized the remaining interface processors and marked as down the CT3IP-50 when it is installed in slot 4. When the CT3IP-50 was reinserted, the system marked the interfaces as down again because the CT3IP-50 interfaces were not shut down before the CT3IP-50 was removed.

When a new CT3IP-50 is inserted, or when a CT3IP-50 whose interfaces are shut down is moved to a new slot, the system recognizes the CT3IP-50 controller, but leaves its interfaces in a shutdown state until you configure them and change the state to up with the configure command. If you move a CT3IP-50 to a new slot and its interfaces were not shut down, the system recognizes them as not shut down when the CT3IP-50 is installed in the new slot.

The following example display shows the events logged by the system as a new CT3IP-50 is inserted in slot 4:

Configuration Guidelines and Configuration Command Examples

This section describes basic configuration guidelines and configuration command examples for the T3 and then T1 interfaces.

Configuring the T3 Interface

Use the following procedure to configure the T3 interface. (Press the Return key after each step.)

Step 2   Specify the controller to configure by entering the subcommand controller, followed by t1 or t3, and slot/port (interface processor slot number/interface port number). The example that follows is for the CT3IP-50 in interface processor slot 3 for T3 channel 0:

Step 3   At the prompt, specify the framing type using the framing [c-bit | m23 | auto-detect] command; set c-bit framing format, as follows:

At the prompt, request the CT3IP-50 to detect the framing type it is to receive from the far end, as follows:

Step 4   Specify the cable length using the cablelength feet command, where feet is expressed as a numeral from 0 to 450, with the default value of 224 feet. Issue the cablelength command as follows:

Note For the cablelength feet command, user-specified T3 cable lengths are structured into ranges as follows: 0-224 and 225-450. If a cable length value is entered that falls into one of these ranges, the range within which that value applies will be used.

In the preceding example, a cable length of 200 is specified. If it is changed to 220, then the 0-224 range applies in each case. Further, if you specify a cable length of 300, then change it to 400, the 225-450 range applies in each case; therefore, these changes have no effect. Only moving from one range to another has an effect. The actual number you enter is stored in the configuration file.

Step 5   Specify the clock source for the controller using the clock source [internal | line] command, which determines which end of the circuit provides the clocking.

Configuring MDL Messages

Maintenance Data Link (MDL) messages (which are defined in the ANSI T1.107a-1990 specification) can be configured on the CT3IP-50.

To configure MDL messages, use the following controller configuration commands:

mdl {transmit {path | idle-signal | test-signal} | string {eic | lic | fic | unit | pfi | port | generator} string}

no mdl {transmit {path | idle-signal | test-signal} | string {eic | lic | fic | unit | pfi | port | generator} string}

where the command arguments are defined as follows:

Use the no form of this command to remove MDL messages. The default is that no MDL message is configured.

Examples of MDL Message Configuration

Following are examples of configuring MDL messages; enter controller configuration mode first, as follows:

Configuring the Logical T1 Interfaces

Use the following procedure to configure the logical T1 interfaces using controller configuration commands. (Examples follow each step.)

Examples follow:

Configure T1 0 for full T1 bandwidth as follows:

Configure the T1 20 to use timeslots 1 through 5 and timeslots 20 through 23 as follows:

Configure the T1 21 for 24 x 56 kbps as follows:

Step 2   Specify the T1 framing format using the t1 t1 channel framing [esf | sf] command. The default is the extended super frame (ESF) framing format, and the T1 channel is 1-28.

Examples follow:

Set super frame (SF) framing format for T1 6 as follows:

Note You can use the [no] t1 t1 channel yellow [detection | generation] command (where T1 channel is 1-28) to turn the detection or generation of a yellow alarm on and off. When you select SF framing, you should consider using the no t1 channel yellow detection command to turn off yellow alarm detection because the yellow alarm can be incorrectly detected with SF framing.

Set ESF framing format for T1 18 as follows:

Step 3   Specify remote T1 line code using the t1 t1 channel linecode [ami | b8zs] command. The default is b8zs, and the T1 channel is 1-28.

An example follows:

Note The default for the logical T1 interfaces is noninverted data; however, if the ami argument is selected with the linecode command, inverted data is required (using the invert data interface subcommand) because the T1 channel is bundled into the T3 signal, so there are no local T1 line drivers and receivers associated with it. Therefore, the t1 0 linecode ami command does not modify local line driver settings. Rather, it advises the CT3IP-50 what line code the remote T1 is using. The CT3IP-50 uses this information solely for the purpose of determining whether or not to enable the pulse density enforcer for that T1 channel.

When the argument b8zs is selected, the pulse density enforcer will be disabled. When the ami argument is selected, the pulse density enforcer will be enabled. To avoid having the pulse density enforcer corrupt data, the T1 interface should be configured for inverted data, as described above, when the ami argument is selected.

Step 4   Specify the T1 clock source using the t1 t1 channel clock source [internal | line] command, where the T1 channel is 1-28, and the default is network (line) clocking.

Examples follow:

Set internal clock source for T1 6 as follows:

Set network clock source for T1 1 as follows:

To remove a T1 channel, use the no t1 t1 channel timeslots 1-24 command, where the T1 channel is 1-28. For example, remove the channel for T1 20 as follows:

Configuring the External T1 Ports on a CT3IP-50

The following controller configuration commands are valid only to the first three T1 channels (T1 0 through 2) when they are broken out to the external T1 port. Configure a T1 Interface as an external port using the t1 external t1 channel [linecode {b8zs | ami}] [cablelength feet] command, where external T1 channels are 1-3, and the cable length range is 0-655 feet. The default values are as follows: line code is B8ZS; cable length is 133 feet.

(Use the show controller t3 command to check the status of the external ports; refer to the example of this command on page 31 of the section "Command Descriptions and Examples.")

For example, configure T1 1 to be an external port as follows:

To remove a T1 interface from an external port, use the no t1 external t1 channel command, where external T1 channels are 1-3.

For example, remove T1 1 from external port 1 as follows:

Configuring the T1 Test Port on a CT3IP-50

The following controller configuration commands are valid only to the T1 test port. Configure the T1 test port using the t1 test t1 test channel [linecode {b8zs | ami}] [cablelength feet] command, where the T1 test channels are 1-28, and the cable length range is 0-655 feet. The default values are as follows: line code is B8ZS; cable length is 133 feet.

(Use the show controller t3 command to check the status of the test port; refer to the example of this command on page 31 of the section "Command Descriptions and Examples.")

For example, bring T1 20 to the test port as follows:

To remove a T1 port from the test port, use the no t1 test t1 test channel command, where T1 test channels are 1-28.

For example, remove T1 20 from the test port as follows:

Additional Commands for CT3IP-50 Configuration

Following are additional commands required to complete the CT3IP-50 configuration:

Step 2   Add any additional interface subcommands required to enable routing protocols and adjust the interface characteristics.

Step 3   After including all of the interface subcommands to complete the configuration, press Ctrl-Z (hold down the Control key while you press Z) to exit configuration mode.

Step 4   Write the new configuration to memory as follows: