PRDT（2，1）架构的NoC系统容错路由算法

链路和节点的故障会导致网络中许多节点无法相互通讯,因此容错性是NoC系统设计中的一个重要问题。基于一种新的NoC网络拓扑结构PRDT（2,1）,提出一种PRDT（2,1）容错路由算法以及相应的节点失效算法。节点失效算法通过使较少数量的无故障节点失效来构造矩形故障区域,PRDT（2,1）容错路由算法仅使用了最小数量的虚拟通道并提供足够的自适应性以实现无死锁容错路由。只要故障区域没有断开网络,这一算法能够保证路由的连通性。算法在不同故障率的PRDT（2,1）网络中仿真,结果显示这一算法具有良好的平滑降级使用特性。     

Mesh网络耐故障虫孔路由

耐故障是互连网络设计中的一个重要问题。本文提出了一种新的耐故障路由算法,并将其应用于使用虫孔交换技术的Mesh网络。由于使用了较低的路由限制,这一算法具有很强的自适应性,可以在各种不同故障域的Mesh网络中保持路由的连通性和无死锁性;由于使用了最小限度的虚拟通道,这一算法所需的缓冲器资源很少,非常适宜构建低成本的耐故障互连网络;由于根据本地故障信息进行绕行故障节点的决策,这一算法的路由决策速度较快并且易于在互连网络中实现。最后网络仿真试验显示,这一算法具有良好的平滑降级使用的性能。     

Torus网络中基于标志位的容错路由

针对Torus结构的多处理机系统中容错路由的问题,提出标志位概念,给出一个基于标志位的容错路由算法。存储于Torus网络中各节点的标志位记录系统中的故障信息,用于判定消息的源节点和目的节点之间是否存在最优通路。标志位的赋值可以通过与邻节点间的信息交换完成。     

基于扩展安全级的Torus网络容错路由算法研究

在存在故障结点的网络中如何设计最小容错路由是网络容错研究中的一个热点问题。以存在矩形故障块的二维Torus网络为例,将扩展安全级运用到Torus中,对于网络中任意一对结点,给出存在最小路径的充要条件;并且结合扩展安全级的概念,给出建立最小通路区的方法,并用实验验证了方法的可行性。研究为存在故障结点的Torus网络寻找最小容错路径提供了理论依据。     

Torus网络中容错路由算法的设计与概率分析

基于k-Torus子网的概念提出了一个简单的Torus网络容错路由算法。假设结点出错相互独立,计算出路由算法成功路由的概率。对于几十万个结点以上的Torus网络,提出的路由算法构造通路的概率可达99%,且所提出的路由算法具有线性的特点。     

具有混合故障广义超立方体中的容错路由

针对广义超立方体网络中的同时具有大量结点和链路故障模式,提出了两类新的局部连通性概念。在这两类局部连通性概念的基础上给出了两个广义超立方体网络的分布式容错路由算法。基于两类新的局部连通性概念的广义超立方体网络容错路由算法与基于局部连通性的广义超立方体网络容错路由容错路由算法相比较,新算法提高了容错能力。     

基于故障节点再利用的细粒度NoC容错路由算法

针对传统NoC容错算法中容错粒度过粗造成资源浪费的问题,提出了一种细粒度的自适应容错路由算法,对带有部分故障的节点重新利用。算法将各种故障映射为一种功能故障模型,结合新提出的路由端口优先级策略和嵌入的奇偶转向模型,实现数据包的无死锁容错路由。实验表明,随着负载和故障数目的增加,该算法具有更优越的容错性能,证明了算法的有效性。     

一种无虚通道NoC负载均衡容错路由算法

随着芯片复杂度的不断增大,设计一个高效的片上网络容错路由算法面临着巨大的挑战。由于芯片面积开销的限制,拥有低面积开销的无虚通道片上网络路由器受到学术界的广泛关注。但目前对无虚通道片上网络容错路由算法的研究却停留在容错性能上,而忽略了容错路由算法的路由路径过于单一所造成的负载不均、数据包平均延迟较大等问题。文章在借鉴已有的奇偶转向容错路由算法的基础上,对算法的故障模型和故障绕行策略进行优化,并在算法中融入负载均衡策略,以形成新的容错算法缓解上述问题。在9x9的2D mesh网络中对新提出的算法和参考算法的仿真结果表明：与参考算法相比,新算法在降低数据延迟和吞吐量方面有着明显的优势,在最优情况下能减少8.92%数据延迟和增加10.46%的吞吐量。     

无虚拟通道的3D NoC ZoneDefense容错路由算法*

3D片上网络能有效解决片上系统的通信问题。本文针对3D Mesh NoC中的节点故障,提出了一种无虚拟通道容错路由算法,称为3D ZoneDefense容错路由算法(3D-ZDFT)。该算法建立在3D防御区域基础之上,3D防御区域能够提供故障体的位置信息。根据防御区域提供的故障体位置信息,3D-ZDFT可提前发现故障位置并改变转发端口,实现容错的同时避免引入死锁。实验结果表明,与HamFA相比,3D-ZDFT有较低的网络延迟和更高的可靠性。面积开销分析显示,3D-ZDFT比HamFA的面积开销高约3.1%。     

基于裂痕故障块的自适应容错路由表算法

基于裂痕故障块的二维网格自适应容错路由算法是一种有效的容错算法,不仅能够解决活锁问题,而且克服了传统故障块模型中状态良好的节点不能参与路由的缺陷,但同时具有明显的缺点：每次路由到以故障块边界节点为根节点的内部树时,都需要遍历此内部树,因此算法的路由长度并不是最短的。针对上述问题,提出基于裂痕故障块的自适应容错路由表算法,其中路由表由裂痕故障块内部树上的节点创建,通过路由表上保留的有用消息决定是否遍历内部树。实验结果证明,随着网格规模的扩大,该算法最大可减少70％的平均路由长度,并且其实现简单,可以有效地延长网络寿命。     

基于局部故障块三维mesh/torus网的容错路由

当系统包含很少的故障点时．mesh/torus网整个系统就有可能是不可靠的．该文采用扩展的局部可靠性信息来指导三维mesh／torus网的容错路由．扩展的局部可靠性信息在每个平面内部对无故障节点分类，所以系统中的故障块也是在不同的平面上构成的，而不是基于整个系统．很多基于整个系统不可靠的节点在二维的平面中都会变成可靠的节点．不管是在可靠的系统内，甚或不可靠的系统内，扩展的局部可靠性信息都能有效地指导容错路由．不同于以往的方法，作者的方法不会将任何无故障节点设置为无效节点．所有的故障块都是在平面内构成的，而不是基于整个系统；在一个平面内．任何包含在故障块里的无故障节点仍然可作为出发点或者目标点，这样将大大提高系统的计算能力和性能．模拟结果表明该文方法大大优于已有的方法．     

Routing in wormhole-switched clustered networks with applicationsto fault tolerance

This paper presents a novel technique for routing in wormhole-switched multiprocessor interconnection networks with clustered configuration. The network model used here consists of a set of clusters interfaced through a common central network. We assume that the central network and the clusters use independent algorithms to route messages between their internal nodes. A technique for deriving a global routing algorithm based on the local algorithms is presented, which allows the transfer of messages between any pair of nodes in the network. This proposed method is shown to be deadlock-free with two virtual channels. The clustered network model and the proposed routing technique can be used to enhance the fault tolerance capability of existing routing algorithms. In particular, we describe fault-tolerant routing methods for meshes, which can tolerate any arbitrary fault distribution without disabling connected healthy nodes     

Fault-Tolerant Wormhole Routing with 2 Virtual Channels in Meshes

In wormhole meshes, a reliable routing is supposed to be deadlock-free and fault-tolerant. Many routing algorithms are able to tolerate a large number of faults enclosed by rectangular blocks or special convex, none of them, however, is capable of handling two convex fault regions with distance two by using only two virtual networks. In this paper, a fault-tolerant wormhole routing algorithm is presented to tolerate the disjointed convex faulty regions with distance two or no less, which do not contain any nonfaulty nodes and do not prohibit any routing as long as nodes outside faulty regions are connected in the mesh network. The processors＇ overlapping along the boundaries of different fault regions is allowed. The proposed algorithm, which routes the messages by X-Y routing algorithm in fault-free region, can tolerate convex fault-connected regions with only two virtual channels per physical channel, and is deadlock- and livelock-free. The proposed algorithm can be easily extended to adaptive routing.     

基于Cayley图的三维六度环面网络研究

提出了一种三维六度环面Cayley图网络模型.针对该网络模型,给出了一种简单的三维节点编址方案,并利用该编址方案得到了任意两个节点间的最短距离公式;开发了一种简单的分布式最优路由算法,该算法可以运行于网络中的任意节点,可以建立任意两点之间的最短路由路径;基于陪集图(coset graph)理论,给出了一种新型的广播通信算法,并对该算法的效率进行了分析;给出了三维六度环绕网络模型直径的界限值.     

Enhanced fault tolerant routing algorithms using a concept of “balanced ring”

Fault rings can be used to guide messages bypass faulty nodes/links in a fault tolerant interconnection network. However, nodes on the fault ring become hot spots, thus causing uneven distribution of the traffic loads. To avoid such traffic congestion, a concept of the balanced ring is proposed in this paper. The proposed balanced ring, defined as concentric rings of a given fault ring, can be applied to the fault tolerant routing algorithms for mesh and torus topologies. By properly guiding messages to route on the balanced ring and the fault ring, more balanced link utilization and greatly reduced traffic congestion can be achieved on a fault tolerant network. Methods of applying the balanced ring concept to some published fault tolerant routing algorithms are discussed. Proof of deadlock and livelock freedom is also presented. The use of balanced ring does not need to add new virtual channels. The performance of two routing algorithms with and without the balanced ring is simulated and evaluated. The results indicate that routing algorithms with the balanced rings constantly yield larger throughput and smaller latency than those without.     

Routing performance enhancement in hierarchical torus network by link-selection algorithm

A hierarchical torus network (HTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 3D-torus networks that are hierarchically interconnected for higher-level networks. The static network performance of the HTN and its dynamic communication performance using the popular dimension-order routing algorithm have already been evaluated and shown to be superior to the performance of other conventional and hierarchical interconnection networks. In this paper, we propose a link-selection algorithm for efficient use of physical links of the HTN, while keeping the link-selection algorithm as simple as the dimension-order routing algorithm. We also prove that the proposed algorithm for the HTN is deadlock-free using three virtual channels. We evaluate the dynamic communication performance of an HTN using dimension-order routing and link-selection algorithms under various traffic patterns. We find that the dynamic communication performance of an HTN using the link-selection algorithm is better than when the dimension-order routing algorithm is used.     

Adaptive deadlock- and livelock-free routing with all minimal pathsin torus networks

This paper consists of two parts. In the first part, two new algorithms for deadlock- and livelock-free wormhole routing in the torus network are presented. The first algorithm, called Channels, is for the n-dimensional torus network. This technique is fully-adaptive minimal, that is, all paths with a minimal number of hops from source to destination are available for routing, and needs only five virtual channels per bidirectional link, the lowest channel requirement known in the literature for fully-adaptive minimal worm-hole routing. In addition, this result also yields the lowest buffer requirement known in the literature for packet-switched fully-adaptive minimal routing. The second algorithm, called 4-Classes, is for the bidimensional torus network. This technique is fully-adaptive minimal and requires only eight virtual channels per bidirectional link. Also, it allows for a highly parallel implementation of its associated routing node. In the second part of this paper, four worm-hole routing techniques for the two-dimensional torus are experimentally evaluated using a dynamic message injection model and different traffic patterns and message lengths     

A fault-tolerant wormhole routing scheme for torus networks with nonconvex faults

In this paper, we present a fault-tolerant routing algorithm for torus networks by using only 4 virtual channels. The proposed algorithm is based on the solid fault model, which includes rectangular faults and many practical nonconvex faults. Previous works need at least 6 virtual channels to achieve the same fault-tolerant ability.     

Multicast communication in wormhole-routed 2D torus networks with hamiltonian cycle model

In this paper, we propose an efficient multipath multicast routing algorithm in wormhole-routed 2D torus networks. We first introduce a hamiltonian cycle model for exploiting the feature of torus networks. Based on this model, we find a hamiltonian cycle in torus networks. Then, an efficient multipath multicast routing algorithm with hamiltonian cycle model (mulitpath-HCM) is presented. The proposed multipath multicast routing algorithm utilizes communication channels more uniformly in order to reduce the path length of the routing messages, making the multicasting more efficient. Simulation results show that the multicast latency of the proposed multipath-HCM routing algorithm is superior to that of fixed and dual-path routing algorithms.