A Congestion Aware Multi-Path Label Switching Scheme in Data Centers Based on SDN

• Main Authors: Hung-YenWang, 王泓硯
• Other Authors: Yeim-Kuan Chang
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/6y38um

碩士 === 國立成功大學 === 資訊工程學系 === 107 === Multi-rooted topologies like leaf-spine, and fat-tree are used in data center networks to provide multiple equal-cost paths between ToR switches. The most commonly used routing protocol to achieve load balance in data centers is equal-cost multi-path routing (ECMP), which routes flows based on the hash value of packet’s headers. Since ECMP makes routing decisions without the network’s congestion status, it may cause significant imbalance between paths, thus leading to low bisection bandwidth utilization. According to the literatures, the traffic pattern in data centers follows a heavy-tailed distribution, that is, a small fraction of flows contribute to most of the bytes in the network. Thus, we decide to carefully route the elephant flows to the least congested path, while we route other flows in a proactive way like ECMP. In this thesis, we propose a routing protocol based on Software-Defined Networking (SDN) architecture, which enables load balancing. This routing protocol aims to provide a better average link utilization for fat-tree. Switches adopt an ECMP like method to route all flows by default. At the same time, we follow the idea of In-band Network Telemetry (INT) to collect link congestion status in data center networks. Edge switches are responsible for detecting elephant flows by running a heavy hitter detection algorithm. When an elephant flow is reported to the controller by an edge switch, our controller will use the collected congestion status to find a least congested path for it. In order to make the switches forward packets more efficiently and reduce the number of rules in switches’ forwarding table, we adopt label switching. Programming Protocol-independent Packet Processors (P4) is an emerging switch describing language. With P4, network developers are able to design the logic how P4 switches process packets. In this thesis, we develop a P4 program to design our novel routing scheme, which contains a heavy hitter detection algorithm. We further validate that our heavy hitter detection algorithm can run on Banzai Machine.We also write a python controller to communicate with P4 switch through P4 Runtime protocol. We use Mininet to construct our testbed, and choose BMv2 as our simulated software P4 switch.