結合Middlebox策略考量以改善軟體定義網路效能

Abstract

Middlebox在現今的網路中扮演著一個不可或缺的角色，諸如防火牆（firewall）、網路地址轉換（Network Address Translation，縮寫為NAT）、負載平衡器（load balancer）等。這些Middlebox提供了安全性、路由方式以及網路管理等功能，而如何確保封包正確的經過我們需要的service chain常需要極大的人力資源。軟體定義網路（Software-Defined Networking，縮寫為SDN），一種集中管理且可程式化的網路的出現，提供了一個可能的解決方案，就算如此，還是有著不少的可以改進的地方。 不同的Middlebox供應商通常有各自不同的部署方式，換句話說，沒有一種統一的使用者介面以便於設定。在送出封包之前，我們並不知道這些Middlebox將會對這些封包採取何種動作。因此，即使我們可以決定走哪條路、經過哪些Middlebox，我們也有可能因為不知道Middlebox會如何處理封包而遇到效能上的瓶頸，另外，在傳統網路中，要拿到網路的即時流量資訊十分的不容易，而有些Middlebox如果有了這方面的資訊，可能可以有更好的效能，負載平衡器便是一個例子。 這篇論文提出了一個結合Middlebox資訊來幫助路由之輕量且符合成本效益的方法。我們在SDN架構中加入一個模組來讓Middlebox給控制器一些REST (Representational State Transfe) API格式的路由相關資訊。藉由此方式，我們可以作出更好的路由決策。

Middleboxes such as firewalls, NAT, load balancer play an important role in the existing networks. They offer security, routing method, and network management, etc. Ensuring the traffic goes through the desired service chain requires plenty of manpower. In this regard, Software-Defined Networking (SDN) provides a centralized, programmable network that can dynamically provision so as to address the needs of businesses. However there are still some things we can do in order to improve the performance. Middleboxes are typically deployed by different vendors as standalone devices, i.e., there is no general user interface to access. The middleboxes may modify or drop the packets and we cannot know before we send the packet. Thus, even if we are able to decide the path to get to the middleboxes, we may meet the performance bottleneck due to the unknown policies of middleboxes. And some middleboxes such as load balancer may be able to have a better performance with the real time network information. Note that it is usually hard for legacy network to do dynamic routing in real time. To address these challenges, this thesis presents a lightweight, cost-effective, and middlebox policy-aware routing method. We add a module in SDN architecture to help middleboxes to give the controller some routing 'hints' in REST (Representational State Transfer) API format. Thus, we can make the proper routing decision.