This document describes, surveys, classifies and compares the protocol mechanisms provided by existing IETF protocols, as background for determining a common set of transport services. It examines the Transmission Control Protocol (TCP), Multipath TCP, the Stream Control Transmission Protocol (SCTP), the User Datagram Protocol (UDP), UDP-Lite, the Datagram Congestion Control Protocol (DCCP), the Internet Control Message Protocol (ICMP), the Realtime Transport Protocol (RTP), File Delivery over Unidirectional Transport/Asynchronous Layered Coding Reliable Multicast (FLUTE/ALC), and NACK-Oriented Reliable Multicast (NORM), Transport Layer Security (TLS), Datagram TLS (DTLS), and the Hypertext Transport Protocol (HTTP) when used as a pseudotransport.