Research And Design Of VIA-based Network Interface Card

The Performace of network storage system is not only relative to storage subsystem, but also network. Traditional network interface techniques do not provide zero-copy mechanism and have upper frequency of interrupts. These result in more load of CPU and have a negative affect on bandwidth and IOPS of storage subsystem. The VIA draft has given an effective resolvent. Analysis indicates that two issues bring in the redundant copy of data. When sending, continuous buffer data should be divided up and protocol heads appended, so temporary buffer is needed. When receiving, the received data frame must be kept in temporary buffer because protocol handler cannot decide which user buffer that is protected will be store the frame before receiving it completely. To solve these problems we have provided one hardware scheme that is compatible with VIA draft and designed a network card-based FPGA for verification. All the work is to improve the bandwidth and IOPS of network storage system.Message Window Mechanism is used to communicate between the Host and NIC. The messages include command, status and buffer descriptors. This is the base of solving above two problems.NIC extracts the protocol heads from the buffer descriptors and inserts it into the front of data that will be sent when being noticed. NIC divides the received frame into Protocol head and data and notice the Host that which user buffer is needed through early interrupt. In order to decrease the interrupt frequency and record burst received packet fragments during interrupt serve period, command queue is adopted.Function verification for some design unit has been done. Results indicate that established object is achieved.