An Implementation of Packet-In Buffer Plugin for OpenFlow Switches

• Main Authors: Ding-Syuan Jhuang, 莊定軒
• Other Authors: Shang-Juh Kao
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/96598928851729593425

碩士 === 國立中興大學 === 資訊科學與工程學系 === 105 === The drastically multimedia applications increased traffic may cause management complexity in the newly developed Software-Defined Networking (SDN). With SDN, when an OpenFlow switch receives a packet, it searches the flow table for a flow match, and forwards the packet to the next hop once the flow is matched in the table. However, a mismatch may result in the packet to be directed to the controller as a packet-in message. When the number of packet-in messages increases, a newly arrived packet may suffer from long latency before it is processed. The packet could be even dropped in case of the packet-in buffer being full. To speed up the processing time of packet-in messages, instead of sending mismatched packets to the controller, we propose a packet-in buffer plugin between OpenFlow switches and the controller as a middle box. Only the header of the mismatched packet is extracted and directed to the controller for the purpose of forwarding determination. The plugin structure includes three modules: packet-in module, packet-out module and packet-buffer storage module. The packet-in module detaches the header and data from the mismatched packet and forwards the new packet containing header and buffer unique identifier (BUID) to the controller as well as stores the data and BUID into the packet-buffer storage. The packet-out module combines the packet-out message, as corresponding to the BUID, with the original data from packet-buffer storage and sends to the destined OpenFlow switch. Our experimental results show that by cutting the size of a packet-in message to 92bytes, we can successfully reduce the congestion occasions at the controller and improve the throughput of the controller. As a result, a single controller is able to manage more switches, and the network can be easily scaled out. However, if the scale of the network is not large enough, then the cost of going through an intermediate buffering device may result in increased latency.