Configuring an SR-MPLS TE Policy (Dynamic Delivery by a Controller)

SR-MPLS TE Policy is a tunneling technology developed based on SR.

Usage Scenario

An SR-MPLS TE Policy can either be manually configured on a forwarder through CLI or NETCONF, or be delivered to a forwarder after being dynamically generated by a protocol, such as BGP, on a controller. The dynamic mode facilitates network deployment.

The candidate paths in an SR-MPLS TE Policy are identified using <Protocol-Origin, originator, discriminator>. If SR-MPLS TE Policies generated in both modes exist, the forwarder selects an SR-MPLS TE Policy based on the following rules in descending order:

Protocol-Origin: The default value of Protocol-Origin is 20 for a BGP-delivered SR-MPLS TE Policy and is 30 for a manually configured SR-MPLS TE Policy. A larger value indicates a higher preference.
<ASN, node-address> tuple: originator of an SR-MPLS TE Policy's primary path. ASN indicates an AS number, and node-address indicates the address of the node where the SR-MPLS TE Policy is generated.
- The ASN and node-address values of a manually configured SR-MPLS TE Policy are fixed at 0 and 0.0.0.0, respectively.
- For an SR-MPLS TE Policy delivered by a controller through BGP, the ASN and node-address values are as follows:
  1. If a BGP SR-MPLS TE Policy peer relationship is established between the headend and controller, the ASN and node-address values are the AS number of the controller and the BGP router ID, respectively.
  2. If the headend receives an SR-MPLS TE Policy through a multi-segment EBGP peer relationship, the ASN and node-address values are the AS number and BGP router ID of the original EBGP peer, respectively.
  3. If the controller sends an SR-MPLS TE Policy to a reflector and the headend receives the SR-MPLS TE Policy from the reflector through the IBGP peer relationship, the ASN and node-address values are the AS number and BGP originator ID of the controller, respectively.
For both ASN and node-address, a smaller value indicates a higher preference.
Distinguisher: A larger value indicates a higher preference. For a manually configured SR-MPLS TE Policy, the value of Distinguisher is the same as the preference value.

The process for a controller to dynamically generate and deliver an SR-MPLS TE Policy to a forwarder is as follows:

The controller collects information, such as network topology and label information, through BGP-LS.
The controller and headend forwarder establish an IPv4 SR-MPLS TE Policy address family-specific BGP peer relationship.
The controller computes an SR-MPLS TE Policy and delivers it to the headend forwarder through the BGP peer relationship. The headend forwarder then generates SR-MPLS TE Policy entries.

Pre-configuration Tasks

Before configuring an SR-MPLS TE Policy, complete the following tasks:

Configure an IGP to ensure that all nodes can communicate with each other at the network layer.
Configure a routing protocol between the controller and forwarder to ensure that they can communicate with each other.

Configuring IGP SR: This section describes how to configure IGP SR.

Configuring BGP Peer Relationships Between the Controller and Forwarder: This section describes how to configure BGP peer relationships between a controller and a forwarder, so that the controller can deliver SR-MPLS TE Policies to the forwarder. This improves SR-MPLS TE Policy deployment efficiency.

Configuring a BGP Extended Community: This section describes how to add a BGP extended community, that is, the Color Extended Community, to a route through a route-policy, enabling the route to be recursed to an SR-MPLS TE Policy based on the color value and next-hop address in the route.

Configuring Traffic Steering: This section describes how to configure traffic steering to recurse a route to an SR-MPLS TE Policy so that traffic can be forwarded through the path specified by the SR-MPLS TE Policy.

Verifying the SR-MPLS TE Policy Configuration: After configuring SR-MPLS TE Policies, verify the configuration.