Configuring the Shortcut Function for SRv6 TE Policies

Enable the shortcut function for SRv6 TE Policies so that an IGP uses an SRv6 TE Policy that is up to perform enhanced SPF calculation.

Prerequisites

Before configuring the shortcut function for SRv6 TE Policies, complete one of the following tasks:

Context

Currently, SRv6 TE Policies are mainly deployed in specific network areas for purposes such as traffic acceleration and load balancing. Sometimes, traffic traversing network areas cannot be effectively steered into the desired SRv6 TE Policy, resulting in an SLA guarantee failure.

An IGP uses an SRv6 TE Policy as a local direct link to perform enhanced SPF calculation. If the headend and endpoint of the SRv6 TE Policy match the ingress and egress of a physical link on the SPF tree, respectively, the IGP uses the SRv6 TE Policy to replace the physical link, implementing the shortcut function for the SRv6 TE Policy.

Although a device on which the shortcut function for SRv6 TE Policies is enabled uses an SRv6 TE Policy as an outbound interface, it does not advertise the SRv6 TE Policy to its neighbors. As such, other devices cannot use the SRv6 TE Policy.

Procedure

Run system-view
The system view is displayed.
Run segment-routing ipv6
SRv6 is enabled, and the SRv6 view is displayed.
Run srv6-te policy name-value endpoint endpoint-ip color color-value
The SRv6 TE Policy view is displayed.
Run encapsulation-mode { encaps | insert-encaps }
An SRv6 TE Policy encapsulation mode is configured.

When forwarded data enters an SRv6 TE Policy, new SID stack encapsulation is required. If no service SID is available, the SRv6 TE Policy needs to use the encaps encapsulation mode. Otherwise, the endpoint cannot remove the SRv6 encapsulation. The headend of the SRv6 TE Policy encapsulates IPv6 header and SRH information into data when the data enters the SRv6 TE Policy, and the endpoint implements the USD flavor to remove the encapsulated IPv6 header and SRH information.

The shortcut function of SRv6 TE Policies does not support the Insert mode.
Run igp shortcut isis [ route-policy route-policy-name ]
The shortcut function is enabled for the SRv6 TE Policy.

If the route-policy route-policy-name parameter is not configured, only 128-bit host routes can recurse to SRv6 TE Policies by default. However, if the route-policy route-policy-name parameter is configured, the specified route-policy is used to selectively recurse routes to SRv6 TE Policies after path calculation is complete.
Run isis ipv6 enable [ instanceId ]
IS-IS IPv6 is enabled for the SRv6 TE Policy, and the ID of the IS-IS process to be associated is specified.
(Optional) Run igp metric { relative relativeValue | absolute absoluteValue }
An IGP metric value is configured for the SRv6 TE Policy used for SPF calculation.

Configure an appropriate IGP metric value for the SRv6 TE Policy to ensure that the SRv6 TE Policy can be correctly advertised and used. For example, the metric value of an SRv6 TE Policy should be less than the metric value of the IGP route that is not expected to be used by traffic.
Run commit
The configuration is committed.

Verifying the Configuration

After the configuration is complete, verify the configuration.

Run the display isis route [ process-id ] ipv6 [ topology topology-name ] [ verbose | [ level-1 | level-2 ] | ipv6-address [ prefix-length ] ] ^* [ | count ] command to check IS-IS routing information.
Run the display ipv6 routing-table ipv6-address [ prefix-length ] [ longer-match ] verbose or display ipv6 routing-table brief command to check IPv6 routing table information.