Configuring IGP SR

This section describes how to configure IGP SR.

Context

An SR-MPLS TE Policy may contain multiple candidate paths that are defined using segment lists. Because adjacency and node SIDs are required for SR-MPLS TE Policy configuration, you need to configure the IGP SR function. Node SIDs need to be configured manually, whereas adjacency SIDs can either be generated dynamically by an IGP or be configured manually.

In scenarios where SR-MPLS TE Policies are configured manually, if dynamic adjacency SIDs are used, the adjacency SIDs may change after an IGP restart. To keep the SR-MPLS TE Policies up, you must adjust them manually. The adjustment workload is heavy if a large number of SR-MPLS TE Policies are configured manually. Therefore, you are advised to configure adjacency SIDs manually and not to use adjacency SIDs generated dynamically.
In scenarios where SR-MPLS TE Policies are delivered by a controller dynamically, you are also advised to configure adjacency SIDs manually. Although the controller can use BGP-LS to detect adjacency SID changes, the adjacency SIDs dynamically generated by an IGP change randomly, causing inconvenience in routine maintenance and troubleshooting.

Procedure

Enable MPLS.
1. Run system-view
  The system view is displayed.
2. Run mpls lsr-id lsr-id
  The LSR ID is set for the local node.
  Note the following issues when setting an LSR ID:
  - LSR IDs must be set before other MPLS commands are run.
  - No default LSR ID is available.
  - Using the IP address of a loopback interface as the LSR ID is recommended for an LSR.
3. (Optional) Run mpls
  MPLS is enabled, and the MPLS view is displayed.
  
  SR-MPLS uses the MPLS forwarding plane, so MPLS needs to be enabled. However, the MPLS capability on the interface is automatically enabled when one of the following conditions is met, and there is no need to configure this step.
  - MPLS is enabled on the interface.
  - Segment Routing is enabled for IGP, and IGP is enabled on the interface.
  - The static adjacency label of the corresponding interface is configured in the Segment Routing view.
4. Run commit
  The configuration is committed.
5. Run quit
  Return to the system view.
Enable SR globally.
1. Run segment-routing
  SR is enabled globally.
2. (Optional) Run local-block begin-value end-value [ ignore-conflict ]
  An SRLB range is configured.
  
  If the system displays a message indicating that the SRLB is used, run the display segment-routing local-block command to view the SRLB ranges that can be set. Alternatively, delete unwanted configurations related to the used label to release the label space.
  
  When the ignore-conflict parameter is specified in the local-block command, if a label conflict occurs, the configuration is forcibly delivered but does not occupy label resources. This function is mainly used for pre-deployment, and the configuration takes effect after the device is restarted.
3. Run commit
  The configuration is committed.
4. Run quit
  Return to the system view.
Configure IGP SR.
In scenarios where SR-MPLS TE Policies need to be manually configured, you are advised to use manually configured adjacency SIDs. In scenarios where a controller dynamically delivers SR-MPLS TE Policies, you are advised to preferentially use manually configured adjacency SIDs. However, you can also use IGP to dynamically generate adjacency SIDs.
- If the IGP is IS-IS, configure IGP SR by referring to Configuring Basic SR-MPLS TE Functions.
- If the IGP is OSPF, configure IGP SR by referring to Configuring Basic SR-MPLS TE Functions.