軟體定義網路化的行動邊緣運算系統下佈建服務鏈時控制層延遲減少之機制

Abstract

服務鏈的配置能提升行動用戶網路傳輸的效能以及安全性。然而在SDN-enabled MEC系統下配置服務鏈比起在傳統雲端計算平台上配置方式來的複雜。由於一個服務鏈中的服務功能可能配置在Edge端或Core端，因此我們必須考慮配置時SDN控制層可能會產生的延遲包括Flow Entry設定到SDN Switch上的時間、處理SDN網路中Flow Table Overflow的時間，以及Edge端和Core端之間訊息交換的時間，一旦控制層的延遲過高就會使得使用者QoE下降，因此在本論文中，我們提出了Hash-based Group Management (HGM)這個服務鏈管理機制，透過這個機制，我們會根據使用者需要的服務鏈種類將使用者分群，每一個群會配置一組服務鏈，之後群中的成員就可共用此服務鏈。此外，我們還用了Hash-based List這種資料結構來管理所有群的資訊以加速分群的進行。與User-based服務鏈管理機制相比，使用HGM能夠減少約50%控制層的延遲。

Service chaining enhances the performance and security of mobile users' traffic. However, compared with traditional cloud computing platform, it is more complicated to deploy service chains in SDN-enabled MEC systems. Services in a chain may be deployed in edge network or core network, therefore, when deploying service chains we need to consider the latency in the SDN control plane including the delay of installing flow entries to SDN switches, the delay of handling flow table overflow in SDN network, and the delay of exchanging messages between edge and core network. High control plane latency degrades the users' QoE. Therefore, in this thesis we proposed a service chain management scheme, Hash-based Group Management (HGM). In this scheme, we assign users into groups according to the required service chain type. For each group, we deploy a service chain shared by group members. To speedup group assignment, we also use a Hash-based List data structure to maintain information of groups. Compared with User-based service chain management scheme, the proposed HGM can reduce 50% control plane latency.