Configuring BGP SR

A controller orchestrates IGP SIDs and BGP SR-allocated BGP peer SIDs to implement inter-AS forwarding over the optimal path.

Context

BGP is a dynamic routing protocol used between ASs. BGP SR is a BGP extension for SR and is used for inter-AS source routing.

BGP SR uses BGP egress peer engineering (EPE) to allocate Peer-Node and Peer-Adj SIDs to peers or Peer-Set SIDs to peer groups. These SIDs can be reported to the controller through BGP-LS for orchestrating E2E SR-MPLS TE tunnels.

Procedure

Configure BGP EPE.
1. Run system-view
  The system view is displayed.
2. Run segment-routing
  SR is enabled.
3. Run quit
  Return to the system view.
4. Run bgp { as-number-plain | as-number-dot }
  BGP is enabled, and the BGP view is displayed.
5. Run peer ipv4-address as-number { as-number-plain | as-number-dot }
  A BGP peer is created.
6. Run peer ipv4-address egress-engineering [ label static-label ]
  BGP EPE is enabled.
7. Run peer ipv4-address egress-engineering link-down { relate-bfd-state | label-pop }
  BGP EPE fault association is enabled.
  
  The relate-bfd-state and label-pop parameters are mutually exclusive. Therefore, you can configure only one of them.
  - With the relate-bfd-state parameter configured, if the inter-AS link corresponding to a BGP EPE label fails, BGP EPE triggers SBFD for SR-MPLS TE tunnel in the local AS to go down. This enables the ingress of the involved SR-MPLS TE tunnel to rapidly detect the failure and switch traffic to another normal tunnel.
  - With the label-pop parameter configured, if the inter-AS link corresponding to a BGP EPE label fails, the ASBR in the local AS pops the BGP EPE label from the received data packet and searches the IP routing table based on the destination address of the packet.
8. (Optional) Configure a peer set.
  1. Run egress-engineering peer-set peer-set-name [ label static-label ]
    A BGP peer set is created.
  2. Run peer ipv4-address peer-set name peer-set-name
    A specified peer is added to the BGP peer set.
  3. Run egress-engineering peer-set peer-set-name link-down { relate-bfd-state | label-pop }
    Link fault association is configured for the BGP peer set.
9. Run commit
  The configuration is committed.
10. Run quit
  Return to the system view
Configure BGP-LS.
BGP-LS provides a simple and efficient method of collecting topology information. You must configure a BGP-LS peer relationship between the controller and forwarder, so that topology information can be properly reported from the forwarder to the controller. This example provides the procedure for configuring a BGP-LS peer relationship on the forwarder. The procedure on the controller is similar to that on the forwarder.
1. Run bgp { as-number-plain | as-number-dot }
  BGP is enabled, and the BGP view is displayed.
2. Run peer ipv4-address as-number as-number-plain
  A BGP peer is created.
3. Run link-state-family unicast
  BGP-LS is enabled, and the BGP-LS address family view is displayed.
4. Run peer { group-name | ipv4-address } enable
  The device is enabled to exchange BGP-LS routing information with a specified peer or peer group.
5. Run commit
  The configuration is committed.

Verifying the Configuration

After configuring BGP SR, verify the configuration:

Run the display bgp egress-engineering command to check BGP EPE information.