UDT

UDT stands for the UDP-based Data Transfer Protocol. It is a high-performance transport protocol built on top of the User Datagram Protocol (UDP) designed to move large data sets over wide-area networks efficiently, especially where long round-trip times and high bandwidth are involved. UDT aims to achieve high throughput while avoiding some of the limitations of TCP in such environments.

The protocol provides reliable, ordered data delivery and flow control using its own congestion control and error-handling mechanisms. UDT runs in user space and uses control messages to manage retransmissions, acknowledgments, and window sizing. By using its own scheme for reliability and congestion control, UDT can adapt to varying network conditions and optimize data transfer rates on high-speed paths.

UDT is commonly used for bulk data distribution, scientific data transfers, and other scenarios where large volumes of data must be moved efficiently between locations connected by wide-area networks. There is a reference open-source implementation, often referred to as the UDT library, which provides the core protocol and bindings for various programming languages and platforms.

Security and interoperability considerations are important when using UDT. Since it operates over UDP, UDT itself does not provide built-in encryption; encryption or authentication must be handled at the application layer or via network-layer tools such as IPsec/TLS. UDP traffic can be blocked or filtered by some firewalls and NAT devices, which can affect transfer feasibility. UDT complements TCP by offering an alternative transport option for suitable high-bandwidth, long-latency transfer tasks.