Configuring the SONET/SDH Layers

When you configure ATM or POS on an interface, you automatically configure default settings at the SONET/SDH layer. To modify the default settings:

1. Select an interface on which you want to configure SONET or SDH.
2. Specify the type of interface: SONET or SDH.
3. Specify a clock source for the interface.
4. (Optional) Assign a text description or an alias to the interface.
5. Disable processing of SNMP link status information for the section and line layers of the interface.
6. Enable processing of SNMP link status information for the path layer of the interface.
7. (Not recommended) Overwrite the automatic setting for the path signal label (C2) byte.
8. Configure the router to use remote defect indications (RDIs) at the path layer to determine the operational status of a path.
9. (MPLS fast reroute over SONET/SDH interfaces) Specify the time that the router waits to set an alarm when the router records a defect at the path layer.
10. (MPLS fast reroute over SONET/SDH interfaces) Specify the time that the router waits to set an alarm when the router records a defect at the line or section layer.
11. Shut down (disable) an interface.

clock source

• Use to configure the transmit clock source for the interface.
• In most cases, accept the default option, line. This setting allows the interface to derive the transmit clock from the received clock. In certain circumstances, it might be appropriate to generate a clock from one of the internal sources (options module or chassis).
• Specify the keyword line to use a transmit clock on 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 firstly to the line setting, and then to the new internal clock setting.
• Example

  host1(config-controll)#clock source internal module

• Use the no version to revert to the default, line.
• See clock source.

controller sonet

• Use to select an interface on which you want to configure SONET or SDH.
• Use the interface specifier in slot/port:path-channel format (ERX-14xx models, ERX-7xx models, and the ERX-310 router) or slot/adapter/port format (E120 router and E320 router). The E120 and E320 routers do not support path channelization, and therefore does not support the path-channel specifier.
• Example 1—Selects a SONET interface on ERX-14xx models, ERX-7xx models, or the ERX-310 router

  host1(config)#controller sonet 4/0

• Example 2—Selects an SONET interface on the E320 router

  host1(config)#controller sonet 3/0/0

• There is no no version.
• See controller sonet.

description

• Use to assign a text description or an alias to an unchannelized SONET 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 64 characters.
• Use show controllers sonet to display the text description.
• Example

  host1(config-controll)#description boston-sonet-interface

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

path description

• Use to assign a text description or an alias to an unchannelized SONET path.
• 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 64 characters.
• Example

  host1(config-controll)#path description westford

• Use the no version to remove the description.
• See path description.

path overhead c2

• Use to overwrite the automatic setting for the path signal label (C2) byte.
• By default, the value of the C2 byte for the path is determined by the layers configured above the SONET/SDH interface and set automatically. The E-series router sets this default value in accordance with RFC 2558. (See References.)

  Caution: Use this command only if you know that the automatic setting does not match the setting on the remote device. Otherwise, the remote device might send an unexpected value, and the router might lose data.

• Do not specify a path identifier for unchannelized SONET/SDH interfaces.
• Example

  host1(config-controll)#path overhead c2 20

• Use the no version to restore the default setting, in which the value of the C2 byte is determined by the layers configured above the SONET/SDH interface.
• See path overhead c2.

path shutdown

• Use to disable a path.
• Paths are enabled by default.
• Example

  host1(config-controll)#path shutdown

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

path snmp trap link-status

• Use to enable SNMP link-status processing for the path layer of the interface.
• The default is disabled.
• Do not specify a path identifier for unchannelized SONET/SDH interfaces.
• Example

  host1(config-controll)#path snmp trap link-status

• Use the no version to disable SNMP link status processing.
• See path snmp trap link-status.

path trigger alarm prdi

• Use to configure the router to use remote defect indications (RDIs) at the path layer to determine the operational status of a path.
• Do not specify a path identifier for unchannelized SONET/SDH interfaces.
• Example

  host1(config-controll)#path trigger alarm prdi

• Use the no version to restore the default setting, in which the software uses loss of pointer and AIS defects at the path layer to determine the operational status of a path.
• See path trigger alarm prdi.

path trigger delay

• Use to set the time that the router waits to set an alarm when the router records a defect at the path layer.
• Change this value from the default only when you are using MPLS fast reroute over a SONET/SDH interface.
  • Specify a value of 0 milliseconds if the interface does not use APS/MSP or if you want MPLS to have priority over APS/MSP.
  • Specify a value of at least 100 milliseconds if this interface uses APS/MSP and you want APS/MSP to have priority over MPLS.
• Do not specify a path identifier for unchannelized SONET/SDH interfaces.
• Example

  host1(config-controll)#path trigger delay msec 1000

• Use the no version to restore the default setting, 2500 milliseconds.
• See path trigger delay.

sdh

• Use to specify that the interface supports SDH.
• Example

  host1(config-controller)#sdh

• Use the no version to revert to SONET operation on this interface.
• See sdh.

shutdown

• Use to disable a SONET/SDH interface.
• SONET/SDH interfaces are enabled by default.
• Example

  host1 (config-controll)#shutdown

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

snmp trap link-status

• Use to enable SNMP link-status processing for the section and line layers of the interface.
• The default is enabled.
• Example

  host1(config-controll)#no snmp trap link-status

• Use the no version to disable SNMP link status processing.
• See snmp trap link-status.

trigger delay

• Use to set the time that the router waits to set an alarm when the router records a defect at the line or section layer.
• Change this value from the default only when you are using MPLS fast reroute over a SONET/SDH interface.
  • Specify a value of 0 milliseconds if the interface does not use APS/MSP or if you want MPLS to have priority over APS/MSP.
  • Specify a value of at least 100 milliseconds if this interface uses APS/MSP and if you want APS/MSP to have priority over MPLS.
• Example

  host1(config-controll)#trigger delay msec 1000

• Use the no version to restore the default setting, 2500 milliseconds.
• See trigger delay.

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