Value,Meaning,Reference,Notes
0,Unknown,"[RFC8029, Section 3.4.1.2]",
1,Static,"[RFC8029, Section 3.4.1.2]",
2,BGP,"[RFC8029, Section 3.4.1.2]",
3,LDP,"[RFC8029, Section 3.4.1.2]",
4,RSVP-TE,"[RFC8029, Section 3.4.1.2]",
5,OSPF,"[RFC8287, Section 6]",To be used for OSPFv2 only.
6,ISIS,"[RFC8287, Section 6]",
7,OSPFv3,[RFC9214],
8-250,Unassigned,,
251-254,Reserved for Experimental Use,[RFC8287],
255,Reserved,[RFC8287],