Black Bus Transmission Technology-based Wormhole Routing Design

With the Multi-processor system on chip (MPSoC) becoming the mainstream design of SoC, Network-on-Chip (NoC) is increasingly focused. NoC is a kind of flexible and scalable micro-network on chip, of which the two main guild lines are the network throughput and the delay.After the retrospection of the basic knowledge of Network-on-Chip (NoC), the data switching mechanism and routing method are analyzed. The wormhole routing in which the data packet is divided into flits and transferred with flits is chosen. This mechanism can not only reduce the delay at each switch, but also occupy few buffers.To solve deadlock, several strategies are discussed. The deterministic routing combining black-bus transfer technique is adopted to solve this"deadlock"problem.In black-bus, a local identifier (ID) is attached to each raw data as the routing information. Unlike traditional packet transfer, the local ID is transferred on a dedicated wire attached to data lines to remove complicated packet generation producers in a node.Only a small sized local ID is required to specify routing tags to destination. And intermediate routers change it to solve the local ID conflicts between path and physic channel.In node design, the traditional wormhole routing and the black-bused wormhole routing are modeled respectively. Packet format in later one omits the data packet header and tail, only using a local ID to tag the flit direction, which reduces the un-packing procedure and enhances the transfer efficiency.To evaluate the network performance between traditional one and black-bused one, 2D-mesh topology was selected to simulate on and results show that the newly method increase 30% efficiency on both network delay and throughput.