Class-based traffic engineering in an IP network

Techniques are described for class-based traffic engineering in an IP network. For example, routers of an IP network may establish one or more constrained traffic engineered paths using a link-state protocol (e.g., IGP) without using signaling protocols, such as RSVP or SPRING, or encapsulating packets over MPLS. For example, an egress router of the IP network may receive a capability message specifying the capability of routers to compute a constrained path to the egress router, wherein the capability message comprises path computation information including an identifier of a path computation algorithm to be used by the one or more of the plurality of network devices to reach the egress network device. The egress router may advertise a reachability message including a destination IP prefix and the identifier of the path computation algorithm to cause routers in the IP network to compute the constrained path to reach the egress router.