Decimal,Name,Description,Reference
1,other,none of the following,[RFC4087]
2,direct,no intermediate header,[RFC2003][RFC4213]
3,gre,GRE encapsulation,[RFC1701][RFC1702][RFC7676]
4,minimal,Minimal encapsulation,[RFC2004]
5,l2tp,L2TP encapsulation,[RFC2661]
6,pptp,PPTP encapsulation,[RFC2637]
7,l2f,L2F encapsulation,[RFC2341]
8,udp,UDP encapsulation,[RFC1234][RFC8085]
9,atmp,ATMP encapsulation,[RFC2107]
10,msdp,MSDP encapsulation,[RFC3618]
11,sixToFour,6to4 encapsulation,[RFC3056]
12,sixOverFour,6over4 encapsulation,[RFC2529]
13,isatap,ISATAP encapsulation,[RFC5214]
14,teredo,Teredo encapsulation,[RFC4380]
15,ipHttps,IPHTTPS,"[Sean_Siler][Microsoft Corporation, ""IP over HTTPS (IP-HTTPS) Tunneling Protocol Specification]"
16,softwireMesh,softwire mesh tunnel,[RFC5565]
17,dsLite,DS-Lite tunnel,[RFC6333]
18,aplusp,A+P encapsulation,[RFC6346]
19,ipsectunnelmode,IpSec tunnel mode encapsulation,[RFC4301]