Research And Implementation Of Key Technologies Of TCP Acceleration-Oriented Protocol Stack

With the rapid devoplement of network and communication technologies, the bandwidth of the network doubles every six months, and now the 10G Ethernet is being deployed. Until now, the processing of TCP/IP over Ethernet is accomplished by software running on the host CPU. It is well established that one herts of CPU processing is required for every one bit per second of network data processed. So the protocol processing can consume large amounts of CPU capacity, and CPU becomes the bottleneck in the end-system. To relieves the host CPU from heavy protocol handling, TCP acceleration has been a hotpot of current research, and the technology TOE (TCP/IP Offload Engine) is proposed.Firstly, this paper introduces the basic principle of TOE, offloading the processing of TCP/IP from the host processor to the hardware on the adapter. Full offload and partial offload are two modes of protocol offload. A TOE implementation consists of hardware and software. The TOE hardware can be implemented with a embedded system, ASICs, or FPGA. And the TOE software can be implemented as two ways, High Performance Sockets and TCP/IP Stack Replacing.Secondly, the paper studies the General Model of Protocol Offloading to capture many of the factors governing the effectiveness of TCP/IP offload, such as application, bandwidth of network path, the capacity of TOE NIC, etc. According to the modeling study, the paper supports that TOE is worthwile, ascertains the appropriate application for TOE, and proposes some advice on how to implement TOE. The modeling study indicates that the time-to-market of TOE NICs should be shorten, considering the long time-to-market for complexy TOE NICs leaves them at the risk of being outstripped by advances in host CPU speeds. It is also realized that TOE fits the application in which the bulk of the overhead is in data transmission and reception.So we decide to offload data path to ease the time-to-market pressure and to relieve the host from the pivotal handling. The paper designs a simple-stuctured TOE software named YH-TOE for a TOE NIC, and studies several key technologies amply to implement the YH-TOE software, which are TCP connection offloading, dual stack cooperation, hardware connection management and high efficient data transmission.In succession, the paper introduces the implementation of YH-TOE software which consists of TOE Offload Module, TOE Net Core Layer and TOE NIC Driver.TOE Offload Module is compatible with existing applications, and in charge of starting the TCP connection offloading. TOE Net Core Layer functions as the interface between TOE NIC Driver and TOE Offload Module. TOE NIC Driver manages TOE NIC to perform the protocol processing. As test has indicated, TOE can relieves the host CPU from heavy protocol handling, remarkably reduces the utilization of host CPU, effectively enhance the performance of data transmission.