Type,Type of Next Hop,Address Length,IF Length,Reference
0,Unassigned,,,
1,IPv4 Numbered,4,4,[RFC8029]
2,IPv4 Unnumbered,4,4,[RFC8029]
3,IPv6 Numbered,16,16,[RFC8029]
4,IPv6 Unnumbered,16,4,[RFC8029]
5,Reserved,,,[RFC6426][RFC7555]
6,IPv4 Protocol Adj,4,0,[RFC7555]
7,IPv6 Protocol Adj,16,0,[RFC7555]
8-255,Unassigned,,,