xns-idp 22 XNS-IDP # Xerox NS IDP
rdp 27 RDP # "reliable datagram" protocol
iso-tp4 29 ISO-TP4 # ISO Transport Protocol class 4 [RFC905]
+dccp 33 DCCP # Datagram Congestion Control Protocol [RFC4340]
xtp 36 XTP # Xpress Transfer Protocol
ddp 37 DDP # Datagram Delivery Protocol
idpr-cmtp 38 IDPR-CMTP # IDPR Control Message Transport