Protocol Number (decimal),Protocol Number (hex),Description,References
0000,0000,reserved,[RFC9542]
0001,0001,MARS Data Messages (short form),[RFC2022]
0002,0002,reserved for future NHRP use,[RFC2332]
0003,0003,MARS/NHRP Control Messages,[RFC2022][RFC2332]
0004,0004,MARS Data Messages (long form),[RFC2022]
0005,0005,SCSP - Server Cache Sync Protocol,[RFC2334]
0006,0006,VRID - Virtual Router MAC Address,[S_Knight]
0007,0007,L2TP,[RFC3070]
0008,0008,Virtual Private Network ID,[RFC2684]
0009-0065,0009-0041,Unassigned,
0066,0042,Documentation Use,[RFC9542]
0067-65534,0043-FFFE,Unassigned,
65535,FFFF,Reserved,[RFC9542]