Configuring T1 Channels on T3 Interfaces

To configure T1 and fractional T1 channels over T3 interfaces:

1. Configure the T1 path.
2. Configure the clock source.

   You must coordinate this setting with the other end of the line to establish which end is the transmit (internal) clock and which is the receive (line) clock.

3. (Optional) Assign a text description or an alias to the interface.
4. (Optional) Configure the framing format.
5. (Optional) Enable processing of SNMP link status information about an interface.
6. Configure the T1 line parameters.

   You can specify parameters for a single channel, multiple individual channels, ranges of channels, or any combination of the three types of specifications. For example:

   host1(config-controll)#path 12 ds3 1 t1 25-28

7. (Optional) Enable processing of SNMP link status information about a channel group.

path ds3 t1

• Use to create and configure the T1 path over SONET and SDH interfaces.
• Example

  host1(config-controll)#path 12 ds3 1 t1 25-28

• Use the no version to delete a path.
• See path ds3 t1.

path ds3 t1 clock source

• Use to configure the transmit clock source for the T3 line.
• Use a transmit clock recovered from the line’s receive data stream, except in rare cases such as back-to-back router tests. When performing back-to-back router tests, 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.
• Specify the keywords internal chassis to use the router’s clock.
• On a cOC3/STM1 I/O module, you can configure some ports with internal clock sources and others with line clock sources. However, all ports with internal clock sources must use either the router’s clock or the module’s clock. You cannot configure some ports on the I/O module to use the router’s clock and others to use the module’s clock.
• To change the clock source of the ports on a cOC3/STM1 I/O module from the router’s clock to the module’s clock or vice versa, change the clock source of all ports first to the line setting, and then to the new internal clock setting.
• Example

  host1(config-controll)#path 12 ds3 1 t1 28 clock source internal chassis

• Use the no version to restore the default value, line clocking.
• See path ds3 t1 clock source.

path ds3 t1 description

• Use to assign a text description or an alias to a T1 or fractional T1 channel on a T3 (DS3) over channelized SONET/SDH 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 sonet ds3 to display the text description.
• Examples

  host1(config-controller)#path 12 ds3 1 t1 28 description boston_t1_on_t3

  host1(config-controller)#path 12 ds3 1 t1 28/5
  description washington_fractional_t1_on_t3

• Use the no version to remove the text description or alias.
• See path ds3 t1 description.

path ds3 t1 framing

• Use to configure the T1 framing format for a T3 interface.
• 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)#path 12 ds3 1 t1 28 framing sf

• Use the no version to restore the default value, esf framing.
• See path ds3 t1 framing.

path ds3 t1 shutdown

• Use to disable T1 channels or a subchannel.
• T1 channels and subchannels are enabled by default.
• Examples

  host1(config-controll)#path 12 ds3 t1 5,9,14-17 shutdown

  host1(config-controll)#path 12 ds3 t1 28/5 shutdown

• Use the no version to restart a disabled interface.
• See path ds3 t1 shutdown.

path ds3 snmp trap link-status

• Use to enable SNMP link status processing for T1 channels or a subchannel.
• The default disables SNMP link status processing.
• Examples

  host1(config-controll)#path 2 ds3 3 t1 28 snmp trap link-status

  host1(config-controll)#path 2 ds3 3 t1 28/5 snmp trap link-status

• Use the no version to disable SNMP link status processing for a T1 channel.
• See path ds3 snmp trap link-status.

path ds3 t1 timeslots

• Use to assign a range of DS0 timeslots to a subchannel as a single data stream.
• You can specify a line speed for all DS0 timeslots assigned to a subchannel.
• Examples

  host1(config-controll)#path 2 ds3 1 t1 28 timeslots 1-10

  host1(config-controll)#path 2 ds3 1 t1 28/1 timeslots 1-10 speed 56

• Use the no version to delete the fractional T1 circuit.
• See path ds3 t1 timeslots.

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