Value,Meaning,Reference
0,Reserved,[RFC8029]
1,IPv4 Numbered,[RFC8029]
2,IPv4 Unnumbered,[RFC8029]
3,IPv6 Numbered,[RFC8029]
4,IPv6 Unnumbered,[RFC8029]
5-250,Unassigned,
251-254,Reserved for Experimental Use,[RFC8029]
255,Reserved,[RFC8029]