As the Internet has evolved, there has been a significant amount of work to develop protocols that more effectively and efficiently move data. The central role transport protocols play in how the Internet works is reflected by the fact that Transport Area working groups often include participation by technologists involved in other Areas such as Security and Routing.
Recently, the QUIC Working Group has been developing a UDP-based, stream-multiplexing, encrypted transport protocol, based on pre-standardization implementation and deployment experience. Key goals for QUIC protocol are minimizing latency, improving performance, and providing always-secure transport that uses TLS 1.3 by default. Work on QUIC has been underway since 2016 and the first specifications are expected to be published as RFCs shortly. IETF has already launched multiple working groups to leverage the services that QUIC provides.
Even well-established transport protocols, such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), which have roots that pre-date the IETF itself, continue to be extended and refined to meet the needs of applications and users of the growing global Internet. One example is Low Latency, Low Loss, Scalable Throughput (L4S), which extends the Explicit Congestion Networking (ECN) framework to potentially lower latency by orders of magnitude. Another is TCP RACK, which seeks to modernize the way that TCP detects packet losses to allow faster recovery.
Another area of work understanding how to best make use of transport protocols to enable networking for devices with differing, and perhaps constrained, connectivity. For example, the DTN (Delay/Disruption Tolerant Networking) Working Group specifies mechanisms for data communications in the presence of long delays and/or intermittent connectivity. More broadly, the TAPS (Transport Services) Working Group is aiming to define how applications interface with underlying transport protocols to improve their ability to use available networking. The IPPM (IP Performance Measurement) Working Group creates standards for operators to safely measure the characteristics of their network. More information about work underway is available in this recent Transport Area introduction presentation.