Exchange_Type,Value,Reference
Reserved,0-3,[RFC4535]
Key Download Ack/Failure,4,[RFC4535]
Rekey Event,5,[RFC4535]
Reserved,6-7,[RFC4535]
Request to Join,8,[RFC4535]
Key Download,9,[RFC4535]
Cookie Download,10,[RFC4535]
Request to Join Error,11,[RFC4535]
Lack of Ack,12,[RFC4535]
Request to Depart,13,[RFC4535]
Departure Response,14,[RFC4535]
Departure Ack,15,[RFC4535]
Reserved to IANA,16-192,[RFC4535]
Private Use,193-255,[RFC4535]