Configuring SRLG

Context

In the networking scenario where the hot standby CR-LSP is set up or TE FRR is enabled, configure the SRLG attribute on the outbound interface of the ingress node of the MPLS TE tunnel or the PLR and the other member links of the SRLG to which the outbound interface belongs.

Configuring SRLG includes:

Configuring SRLG for the link
Configuring SRLG path calculation mode for the tunnel
Deleting the member interfaces of all SRLGs

Perform the following configurations according to actual networking.

Procedure

Configuring SRLG for the link
Perform the following configurations on the links which are in the same SRLG.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
4. Run mpls te srlg srlg-number
  The interface is configured as an SRLG member.
  
  On a network with CR-LSP hot standby or TE FRR configured, the SRLG attribute can be configured for the outbound interface of the ingress node of the MPLS TE tunnel or the PLR and other members of the SRLG to which the outbound interface belongs. A link joins an SRLG after the SRLG attribute is configured on an outbound interface of the link.
Configuring SRLG path calculation mode for the tunnel
Perform the following configurations on the ingress node of the hot-standby tunnel or the TE FRR tunnel.
1. Run system-view
  The system view is displayed.
2. Run mpls
  The MPLS view is displayed.
3. Run mpls te srlg path-calculation [ strict | preferred ]
  The SRLG path calculation mode is configured.
  If you specify the strict keyword, CSPF avoids the following links when calculating the bypass CR-LSP or backup CR-LSP:
  - Link with the same SRLG attributes as SRLG attributes of the primary CR-LSP
  - All links along the primary CR-LSP regardless of whether the links are configured with SRLG attributes
  CSPF does not exclude the nodes that the primary CR-LSP passes.
  - If you specify the strict keyword, CSPF always considers the SRLG as a constraint when calculating the path for the bypass CR-LSP or the backup CR-LSP.
  - If you specify the preferred keyword, CSPF tries to calculate the path which avoids the links in the same SRLG as protected interfaces; if the calculation fails, CSPF does not consider the SRLG as a constraint.
Delete the member interfaces of all SRLGs.
Perform the following configurations to delete member interfaces of all SRLGs from a node of the MPLS TE tunnel.
1. Run system-view
  The system view is displayed.
2. Run mpls
  The MPLS view is displayed.
3. Run undo mpls te srlg all-config
  The member interfaces of all SRLGs are deleted from the MPLS TE node.
  
  The undo mpls te srlg all-config does not delete an SRLG-based path calculation mode configured in the mpls te srlg path-calculation command in the MPLS view.