基于Clos网络的高阶路由器结构

A Clos network based high-radix router structure

路由器为高性能互连网络的关键组成部分,利用高阶路由器可灵活构建网络直径低、路由路径丰富、容错性能高的拓扑结构。分层结构将整个路由器分成多个子交叉开关实现,子交叉开关规模较小,典型实现为子交叉开关的数量等于路由器端口数,每个子交叉开关对应一个输入/输出端口。分层结构每个子交叉开关的输入和输出都设有缓冲区,导致分层结构路由器内部有大量缓冲区,扩展性受限。网络结构将用于构建系统的网络拓扑实现在片内,如通过网格、全互连或胖树连接较小的交换机,并通过集成电路技术实现在一个路由器中,对外表现为一个高阶路由器。网络结构成本低,构建系统网络后除了要考虑系统网络拓扑的性能,还需要考虑路由器本身的路由问题。提出基于Clos网络的分层结构路由器,综合了传统分层结构高性能和网络结构低成本的优点,并提出2种Clos网络的调度算法,在均匀流量模式下接近100%带宽,RTL综合评估其实现最多减少面积25.9%。

The router is a key component of the high performance interconnect network,which can flexibly build a topology with low network diameter,rich routing path and high fault tolerance performance.The hierarchical structure divides the entire router into multiple small subcrossbars.The typical number of sub-crossbar switches is equal to the number of router ports,and each sub-crossbar switch corresponds to an input and output port.The input and output of each subcrossbar are equipped with buffers,resulting in a large number of buffers inside the hierarchical router that limits the scalability.The network structure will be used to build the network topology of the system in a chip,such as connecting smaller switches through a grid,a full interconnect,or a fat tree implemented in a router through integrated circuit technology,which externally appears as a high radix router.Network structures have low costs and require consideration of not only the system network topology’s performance after building the system network but also the router’s own routing issues.This paper proposes a hierarchical structure router based on Clos network,combining the advantages of high performance and low cost of traditional hierarchical structure,and proposes two schedule algorithms for Clos network.In uniform traffic mode,they approach 100%bandwidth utilization,and the RTL synthesis evaluation achieves a maximum area saving of 25.9%.