Configuring an IS-IS SR-MPLS TE Tunnel (Path Computation on the Controller)

An SR-MPLS TE tunnel is configured on a forwarder. The forwarder delegates the tunnel to a controller. The controller generates labels and calculates a path.

Usage Scenario

Currently, each LSP of a TE tunnel is allocated with a label stack, and tunnel creation and LSP generation are both completed by forwarders. This increases the burden on forwarders and consumes a lot of forwarder resources. To address this issue, SR-MPLS TE can be used to manually create tunnels. This method offers the following benefits:

A controller generates label stacks, reducing the burden on forwarders.
The controller computes paths and allocates a label stack to each route, reducing both the burden and resource usage on the forwarders. As such, the forwarders can focus more on core forwarding tasks, improving forwarding performance.

Pre-configuration Tasks

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

Configure IS-IS to enable LSRs to communicate at the network layer.

A controller must be configured to generate labels and compute an LSP for the SR-MPLS TE tunnel to be established.

Enabling MPLS TE: Enabling MPLS TE on each node in an SR-MPLS domain is the prerequisites for configuring an SR-MPLS TE tunnel.

Enabling SR Globally: Enabling SR globally on forwarders is a prerequisite for SR-MPLS TE tunnel configuration.

Configuring IS-IS SR-MPLS TE and Topology Reporting: Before an SR-MPLS TE tunnel is established, IS-IS SR-MPLS TE and topology reporting must be enabled.

Configuring an SR-MPLS TE Tunnel Interface: A tunnel interface must be configured on an ingress so that the interface is used to establish and manage an SR-MPLS TE tunnel.

Configuring the UCMP Function of the SR-MPLS TE Tunnel: When multiple SR-MPLS TE tunnels are directed to the downstream device, the load balancing weights can be configured to perform the Unequal Cost Multi-Path Load Balance (UCMP) on the SR-MPLS TE tunnels.

(Optional) Configuring SR on a PCC: Configure SR on a PCE client (PCC), so that a controller can deliver path information to the PCC (forwarder) after path computation.

Verifying the IS-IS SR-MPLS TE Tunnel Configuration: After configuring an automatic SR-MPLS TE tunnel, verify information about the SR-MPLS TE tunnel and its status statistics.