The interconnection network is a key element in High-Performance Computing (HPC) and Datacenter (DC) systems whose performance depends on several design parameters, such as the topology, the switch architecture, and the routing algorithm. Among the most common topologies in HPC systems, the Fat-Tree offers several shortest-path routes between any pair of end-nodes, which allows multi-path routing schemes to balance traffic flows among the available links, thus reducing congestion probability. However, traffic balance cannot solve by itself some congestion situations that may still degrade network performance. Another approach to reduce congestion is queue-based flow separation, but our previous work shows that multi-path routing may spread congested flows across several queues, thus being counterproductive. In this paper, we propose a set of restrictions to improve alternative routes selection for multi-path routing algorithms in Fat-Tree networks, so that they can be positively combined with queuing schemes.

互连网络是高性能计算（HPC）和数据中心（DC）系统中的关键元素，其性能取决于几个设计参数，例如拓扑，交换器体系结构和路由算法。在HPC系统中最常见的拓扑中，胖树提供了任意一对末端节点之间的最短路径路由，这允许多路径路由方案在可用链路之间平衡流量，从而降低了拥塞概率。但是，流量平衡无法单独解决某些可能仍然降低网络性能的拥塞情况。减少拥塞的另一种方法是基于队列的流分离，但是我们先前的工作表明，多路径路由可能会将拥塞的流分布到多个队列中，从而适得其反。在本文中，