Value,Protocol ID,References
0,RESERVED,[RFC2407]
1,PROTO_ISAKMP,[RFC2407]
2,PROTO_IPSEC_AH,[RFC2407]
3,PROTO_IPSEC_ESP,[RFC2407]
4,PROTO_IPCOMP,[RFC2407]
5,PROTO_GIGABEAM_RADIO,[RFC4705]
6-248,Unassigned,
249-255,Reserved for private use,