Value,Meaning,Reference
0,Reserved,[RFC9041]
1,MPLS Echo Request,[RFC8029]
2,MPLS Echo Reply,[RFC8029]
3,MPLS Proxy Ping Request,[RFC7555]
4,MPLS Proxy Ping Reply,[RFC7555]
5,MPLS Relayed Echo Reply,[RFC7743]
6-247,Unassigned,
248-251,Reserved for Experimental Use,[RFC9041]
252-255,Reserved for Private Use,[RFC8029]