利用軟體定義網路進行基於網路通道之有效多路徑 BGP 路由

Abstract

這篇論文中提出一個利用軟體定義網路進行基於網路通道之多路徑BGP路由的演算法。BGP是目前在網際網路上唯一一個被廣泛部署之域間路由演算法，且從該標準提出後多年至今的數十年間無大規模修改。BGP基於目的位置的路由方式導致網路中局部連結過載，而其他部分連結使用量過低。先前已有許多研究提出多路徑路由演算法，但這些研究專注於位置之可達性與路徑之傳播，而這些研究均無考慮到路徑之可乘載容量。 當雍塞發生時，封包遺失與控制雍塞機制會使傳送之頻寬下降，即時串流應用無法獲得足夠的頻寬，使服務無法使用。傳統域間流量規劃技術仍受BGP目的位置路由之限制，無法完全控制路由路徑。這篇論文中，目的端可以給予來源端路徑品質之回饋。這些回饋會被用來偵測路徑上之雍塞，來源端以此來調整路由。 透過建立跨越自治系統之網路通道來克服BGP之限制。在有明確網路通道之流量需求資訊下，實驗結果顯示出可以降低網路之雍塞程度。

This thesis presents a tunnel-based multi-path inter-domain routing algorithm under Border Gateway Protocol (BGP) environment using Software-defined Networking. BGP has been the only widely-deployed inter-domain routing protocol on the Internet, and remains little changes over decades. The destination-based routing nature of BGP is known to overload popular links on the Internet, while making some links under-utilized. Prior works had proposed multi-path inter-domain routing protocols. These works focus on reachability and propagation of multi-path information. None of them take the capacity of the path into consideration. In the presense of congestion, packet loss and congestion avoidance mechanisms can lead to inadequate bandwidth required for realtime streaming, making services unusable. Traditional traffic engineering techniques over inter-domain are still limited by destination-based nature of BGP, which is unable to fully control the route. In this thesis, destinations can provide feedback about path quality to the source. The feedback is used to detect congestions on routes and for source to adjust routes accordingly. Tunnels are allocated over Autonomous Systems to overcome the limitation of BGP. With explicitly knowing the demand of tunnels, evaluation shows reduced congestions over the networks.