=== Support for Routing Metric

Contact: Pouria Mousavizadeh Tehrani <pouria@FreeBSD.org>

I have been working on the metric implementation since 2026Q1.
Routing metrics are configuration values used by a router to make routing decisions.
Router metrics help the routing stack to choose the best route among multiple feasible routes to a destination.
The route will go in the direction of the gateway with the lowest metric.
Support for metric in our routing stack is implemented and available in CURRENT.
Metric support requires numerous updates to both kernel and userland.

These are some highlights that were added:

* Support for metric in rtsock via rmx_metric.
* RTA_PRIORITY support for metric in netlink.
* The upper 8-bit weight reservation for metric has been removed.
* man:route[8] now shows the metric value.
* man:netstat[1] now shows the metric value of each route when -w is used.

You can also leverage metric using package:net/bird[] for your routing protocols.
