Abbreviated as TSO, TCP segmentation offload is used to reduce the CPU overhead of TCP/IP on fast networks. TSO breaks down large groups of data sent over a network into smaller segments that pass through all the network elements between the source and destination. This type of offload relies on the network interface controller(NIC) to segment the data and then add the TCP, IP and data link layer protocol headers to each segment. The NIC must support TSO. TSO is also called large segment offload (LSO).
See “Understanding The Data Link Layer” in Webopedia’s Did You Know section.