# Configuration Tasks

To configure a channelized T3 interface:

1. Configure a T3 controller.
2. (Optional) Configure MDL settings.
3. (Optional) Configure other settings for the interface.
4. Configure T1 channels and subchannels.
5. Configure HDLC channels.

## Configuring a T3 Controller

To configure a T3 controller:

1. Access Controller Configuration mode by specifying the T3 controller.
   host1(config)#controller t3 0/1
2. Enable the T3 controller.

   T3 controllers are disabled by default.

   host1(config-controll)#no shutdown

controller t3

- Use to specify a T3 controller in slot/port format.
  - slot—Number of the slot in which the line module resides in the chassis
  - port—Number of the port on the I/O module
- Example
  host1(config)#controller t3 0/1
- There is no no version.
- See controller t3.

shutdown

- Use to disable a T3 controller.
- The T3 interface is disabled by default.
- Example
  host1(config-controll)#no shutdown
- Use the no version to restart a disabled interface.
- See shutdown.

### Configuring MDL Messages

You can configure a channelized T3 interface to send MDL messages. MDL messages are supported only when T3 framing uses C-bit parity, the default setting.

To configure a channelized T3 interface to send MDL messages:

1. Specify a T3 interface.
   host1(config)#controller t3 8/0
2. (Optional) Configure the interface to operate in an MDL carrier environment.
   host1(config-controll)#mdl carrier
3. Specify the MDL messages.
   host1(config-controll)#mdl string eic "ERX1410" host1(config-controll)#mdl string fic "FG786" host1(config-controll)#mdl string lic "Bldg 10" host1(config-controll)#mdl string pfi "Site 25" host1(config-controll)#mdl string port 0800 host1(config-controll)#mdl string unit 080001
4. Enable transmission of MDL messages.
   host1(config-controll)#mdl transmit path-id host1(config-controll)#mdl transmit idle-signal host1(config-controll)#mdl transmit test-signal

mdl carrier

- Use to specify that an interface is used in the carrier environment.
- Example
  host1(config-controll)#mdl carrier
- Use the no version to restore the default situation, in which the interface does not operate in the carrier environment.
- See mdl carrier.

mdl string

- Use to specify an MDL message.
- Example
  host1(config-controll)#mdl string port 0800
- Use the no version to restore the default value to the specified MDL message or to all MDL messages.
- See mdl string.

mdl transmit

- Use to enable transmission of MDL messages.
- Specify the keyword path-id to transmit path identifications every second.
- Specify the keyword idle-signal to send idle signals every second.
- Specify the keyword test-signal to transmit test signals every second.
- Example
  host1(config-controll)#mdl transmit test-signal
- Use the no version to disable transmission of the specified MDL message or all MDL messages.
- See mdl transmit.

### Other Optional Tasks

The following configuration tasks are optional when you configure a T3 controller:

- Specify a cable length.
- Change the clock source.
- Change the framing format.
- Enable or disable SNMP link status processing.
- Assign a text description or an alias to the interface.

cablelength

- Use to adjust the transmit power appropriate to the length of the T3 cable.
- Specify a cable length in the range 1–450 feet.
- The router supports two transmit powers, one for a cable length 1–225 feet and another for a cable length 226–450 feet. Therefore, it is not necessary for you to know the exact length of your cable. You only need to know if the cable length is greater than 225 feet. For example, if your cable size exceeds 225 feet, specify any number greater than 225 (and less than 451).
- Example
  host1(config-controll)#cablelength 300
- Use the no version to restore the default value, 0 feet.
- See cablelength.

clock source

- Use to configure the transmit clock source for a T3 controller.
- Configure one end of the line as internal and the other end as line.
- Specify the keyword line to use a transmit clock recovered from the line’s receive data stream.
- Specify the keywords internal module to use the line module’s internal clock as the transmit clock.
- Specify the keywords internal chassis to use the router’s clock as the transmit clock.
- Example
  host1(config-controll)#clock source internal module
- Use the no version to revert to the default, line.
- See clock source.

description

- Use to assign a text description or an alias to a channelized T3 interface.
- You can use this command to help you identify the interface and keep track of interface connections.
- The description or alias can be a maximum of 80 characters.
- Use show controllers t3 to display the text description.
- Example
  host1(config-controll)#description toronto ct3 interface
- Use the no version to remove the text description or alias.
- See description.

framing

- Use to configure the framing format for a T3 controller.
- Specify either m23 or c-bit framing.
- Choose the framing format that is compatible with the framing format of the Telco network device at the other end of the line.
- Select c-bit framing if you intend to configure MDL messages.
- Example
  host1(config-controll)#framing c-bit
- Use the no version to restore the default value, c-bit.
- See framing.

snmp trap ip link-status

- Use to enable SNMP link status processing on a T3 controller.
- Example
  host1(config-controll)#snmp trap link-status
- Use the no version to disable SNMP link status processing.
- See snmp trap ip link-status.

## Configuring T1 Channels

To configure T1 channels and subchannels:

1. From Global Configuration mode, specify the T3 controller in slot 0, port 1.
   host1(config)#controller t3 0/1
2. Assign a range of timeslots to a channel and subchannel.

   For example, assign the following range of timeslots: 1, 3–8, and 10 to channel 2, subchannel 1. Timeslots 2, 9, and 11–24 are available for other subchannels.

   host1(config-controll)#t1 2/1 timeslots 1,3-8,10

### Optional Tasks

The T1 channel configuration commands enable you to specify options for a single channel, multiple individual channels, ranges of channels, or any combination of the three types of specifications. For example:

host1(config-controll)#t1 2,4,6-15,20-25 clock source line

The following configuration tasks are optional when you configure T1 channels:

- Disable T1 channels.
- Change the clock source.
- Assign a text description or an alias to the interface.
- Change the framing format.
- Enable or disable SNMP link status processing.
- Configure FDL messages.

controller t3

- Use to specify a T3 controller in slot/port format.
  - slot—Number of the slot in which the line module resides in the chassis
  - port—Number of the port on the I/O module
- Example
  host1(config)#controller t3 0/1
- There is no no version.
- See controller t3.

t1 clock source

- Use to configure the transmit clock source for T1 channels.
- The router supports internal and line clocking.
  - If you specify internal clocking, the interface transmits data using the line module or the chassis as the internal clock. You must specify one of the following for internal clocking:
    - module—Specifies internal clock is from the line module itself
    - chassis—Specifies internal clock is from the configured router clock
  - If you specify line clocking, the interface transmits data with a clock recovered from the line’s receive data stream.
- Example
  host1(config-controll)#t1 2,4-10 clock source line
- Use the no version to restore the default value, line.
- See t1 clock source.

t1 description

- Use to assign a text description or an alias to T1 or fractional T1 channels on a CT3 module.
- You can use this command to help you identify the interface and keep track of interface connections.
- The description or alias can be a maximum of 80 characters.
- Use show controllers t3 to display the text description.
- Examples
  host1(config-controll)#t1 2 description london t1 interface host1(config-controll)#t1 2/1 description london first ft1 interface
- Use the no version to remove the text description or alias.
- See t1 description.

t1 framing

- Use to configure the framing format for T1 channels.
- You must specify either esf (extended superframe) or sf (superframe) framing.
- The framing format you choose must be compatible with the framing format at the other end of the line.
- Example
  host1(config-controll)#t1 2 framing sf
- Use the no version to restore the default value, esf.
- See t1 framing.

t1 shutdown

- Use to disable T1 channels or a subchannel.
- To disable channels or a subchannel, specify one or more T1 channels or a subchannel in channel or channel/subchannel format.
  - channel—One or more T1 channels, or a range of channels in the range 1–28
  - subchannel—Subchannel from 1–24
- The T1 interface is enabled by default.
- Example
  host1(config-controll)#t1 4-15,18,21,25-27 shutdown
- Use the no version to restart a disabled interface.
- See t1 shutdown.

t1 snmp trap link-status

- Use to enable SNMP link status processing on T1 channels.
- To enable or disable SNMP on an interface, specify T1 channels or subchannel in channel or channel/subchannel format.
  - channel—One or more T1 channels, or a range of channels in the range 1–28
  - subchannel—Subchannel from 1–24
- Example
  host1(config-controll)#t1 2 snmp trap link-status
- Use the no version to disable SNMP link status processing.
- See t1 snmp trap link-status.

t1 timeslots

- Use to assign a range of DS0 timeslots to a subchannel as a single data stream.
- To configure a subchannel, specify a T1 channel in channel/subchannel format and a range of timeslots.
  - channel—T1 channel in the range 1–28
  - subchannel—Number from 1–24
  - dash—Represents a range of timeslots; a comma separates timeslots. For example, 1-10, 15-18 assigns timeslots 1–10 and 15–18.
- Example
  host1(config-controll)#t1 2/1 timeslots 1,3-8,10
- You can specify a line speed that applies to all DS0 timeslots assigned to a subchannel. The default line speed is 64 Kbps.
- Use the no version to delete the fractional T1 circuit.
- See t1 timeslots.

### Configuring FDL Messages

To configure T1 channels to send FDL messages:

1. Specify a T3 interface.
   host1(config)#controller t3 8/0
2. Specify the standard for transmission of FDL messages on both ends of the T1 connection.
   host1(config-controll)#t1 1 fdl ansi
3. (Optional) Configure one or more T1 channels to operate in an FDL carrier environment.
   host1(config-controll)#t1 1 fdl carrier
4. (ANSI signals) Specify the FDL messages.
   host1(config-controll)#t1 1 fdl string eic "ERX1410" host1(config-controll)#t1 1 fdl string fic "HY0019" host1(config-controll)#t1 1 fdl string lic "Bldg 10" host1(config-controll)#t1 1 fdl string unit 080001 host1(config-controll)#t1 1 fdl string pfi "Site 25" host1(config-controll)#t1 1 fdl string port 0800 host1(config-controll)#t1 1 fdl string generator "Test generator"
5. Enable transmission of FDL messages.
   host1(config-controll)#t1 1 fdl transmit path-id
6. (Optional) Specify that the router should generate yellow alarms for the T1 channels.
   host1(config-controll)#t1 1 yellow generate
7. (Optional) Specify that the router should detect yellow alarms for the T1 channels.
   host1(config-controll)#t1 1 yellow detect

t1 fdl

- Use to specify the FDL standard for the channel.
- Specify one or more T1 channels or a range of channels in the range 1–28.
- Specify the keyword ansi to support the ANSI FDL standard (see References).
- Specify the keyword att to support the AT&T FDL standard (see References).
- Specify the keyword all to support both the ANSI and AT&T standards
- Specify the keyword none to remove the current FDL mode settings
- You can configure a different standard on each T1 channel.
- Example
  host1(config-controll)#t1 14-20,24 fdl att
- Use the no version to restore the default, none.
- See t1 fdl.

t1 fdl carrier

- Use to specify that T1 channels are used in the carrier environment.
- Example
  host1(config-controll)#t1 6 fdl carrier
- Use the no version to restore the default situation, in which the T1 channels do not operate in the carrier environment.
- See t1 fdl carrier.

t1 fdl string

- Use to specify an FDL message as defined in the ANSI T1.403 specification.

  | Note: The router sends these FDL messages only if you have issued the t1 fdl command with the ansi or all keyword and then issued the t1 fdl transmit command.

- Example
  host1(config-controll)#t1 6 fdl string eic "ERX1440"
- Use the no version to restore the default value to the specified FDL message or to all FDL messages.
- See t1 fdl string.

t1 fdl transmit

- Use to configure the router to send the specified type of FDL message.
- By default, the router sends only FDL performance data messages.

  | Note: The router sends FDL messages specified with t1 fdl string only if you have issued the t1 fdl command with the ansi or all keyword. If you specified the att keyword with the t1 fdl command, the router sends only performance data.

- Specify the keyword path-id to transmit path identifications every second.
- Specify the keyword idle-signal to send idle signals every second.
- Specify the keyword test-signal to transmit test signals every second.
- Example
  host1(config-controll)#t1 28 fdl transmit path-id
- Use the no version to disable transmission of the specified FDL message or all FDL messages.
- See t1 fdl transmit.

t1 yellow detect

- Use to detect yellow alarm for T1 channels.
- By default, T1 channels detect alarms.
- Example
  host1(config-controll)#t1 6,10-14,19 yellow detect
- Use the no version to disable detection of yellow alarms.
- See t1 yellow.

t1 yellow generate

- Use to generate a yellow alarm when a loss of frame or loss of signal condition is detected on T1 channels.
- By default, T1 channels generate alarms.
- Example
  host1(config-controll)#t1 6,10-14,19 yellow generate
- Use the no version to disable generation of yellow alarms.
- See t1 yellow.

## Configuring an HDLC Channel

You must configure an HDLC channel for each group of fractional T1 lines and each full T1 line.

To configure an HDLC channel, specify a serial interface (for example, HDLC channel in slot 0, port 1, channel 1, subchannel 5).

host1(config)#interface serial 0/1:1/5

### Optional Tasks

The following configuration tasks are optional when you configure an HDLC channel on a channelized T3 interface:

- Configure the CRC.
- Specify the HDLC idle character.
- Enable data inversion on the interface.
- Set the time interval for monitoring bit and packet rates.
- Set the MRU.
- Set the MTU.
- Assign a text description or an alias to the serial interface.

crc

- Use to configure the size of the CRC.
- The CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data.
- 16 and 32 indicate the number of bits per frame that are used to calculate the frame check sequence (FCS). Both the sender and receiver must use the same setting.
- Use a 32-bit CRC when transmitting long streams at fast rates and to provide better ongoing error detection.
- Example
  host1(config-if)#crc 32
- Use the no version to restore the default value, 16.
- See crc.

idle-character

- Use to configure the HDLC idle character.
- The idle character is sent between HDLC packets.
- Specify one of the following idle characters:
  - flags—Sets the idle character to 0x7E
  - marks—Sets the idle character to 0xFF
- Example
  host1(config-if)#idle-character marks
- Use the no version to restore the default value, 0x7E (flags).
- See idle-character.

interface serial

- Use to configure a serial interface in the slot/port:channel/subchannel format.
  - slot—Number of the slot in which the line module resides in the chassis
  - port—Number of the port on the I/O module
  - channel—T1 channel
  - subchannel—Subchannel in the range 1–24
- Example
  host1(config)#interface serial 0/1:1/5
- Use the no version to disable the interface.
- See interface serial.

invert data

- Use to enable data stream inversion for the interface.
- Enable data stream inversion only if it is turned on at the other end of the line.
- Example
  host1(config-if)#invert data
- Use the no version to disable data inversion.
- See invert data.

load-interval

- Use to set the time interval at which the router calculates bit and packet rate counters.
- You can choose a multiple of 30 seconds, in the range 30–300 seconds.
- Example
  host1(config-if)#load-interval 90
- Use the no version to restore the default value, 300 seconds.
- See load-interval.

mru

- Use to configure the MRU size for the interface.
- Specify a value in the range 4–9996 bytes.
- You should coordinate this value with the network administrator on the other end of the line.
- If you configure a different MRU value in higher-level protocols, such as IP, the router uses the lower value. This can produce unexpected behavior in your network.
- Example
  host1(config-if)#mru 1600
- Use the no version to restore the default, 1600 bytes.
- See mru.

mtu

- Use to configure the MTU size for the interface.
- Specify a value in the range 4–9996 bytes.
- You should coordinate this value with the network administrator on the other end of the line.
- If you configure a different MTU value in higher-level protocols, such as IP, the router uses the lower value. This can produce unexpected behavior in your network.
- Example
  host1(config-if)#mtu 1600
- Use the no version to restore the default, 1600 bytes.
- See mtu.

serial description

- Use to assign a text description or an alias to a serial HDLC interface.
- You can use this command to help you identify the interface and keep track of interface connections.
- The description or alias can be a maximum of 80 characters.
- Use show interfaces serial to display the text description.
- Example
  host1(config-if)#serial description ottawa012 hdlc channel
- Use the no version to remove the text description or alias.
- See serial description.