1 Implementation of a Software-based TCP/IP Offload Engine Using Standalone TCP/IP Stacks without an Embedded OS

A number of TCP/IP offload engines have been developed to reduce the CPU load of processing TCP/IP, but most of them are implemented in hardware. Although hard-ware-based TOEs have a high performance, they lack the flexibility to accept changes in the TCP/IP. To preserve flexibility, we implemented a software-based TOE, called HL-TCP (High-performance Lightweight TCP/IP). The HL-TCP is a standalone TCP/IP stack with-out an embedded OS. The TOE using the HL-TCP has features of a zero-copy sending me-chanism and an efficient DMA mechanism for TCP retransmission. It also fully utilizes of-fload features in the Ethernet. Our experimental results show that the TOE using the HL-TCP can achieve a bandwidth of 453 Mbps with almost zero CPU utilization, compared with a general gigabit Ethernet, which has a CPU utilization of approximately 23%