寬頻的到來使得家庭用戶能從Internet使用多媒體資料。Home gateway為提供家中電腦及資訊家電存取Internet的寬頻設備，在Home gateway相關的研究中包含了為連接Home network使用多種網路技術，保全，服務資訊提供及網路品質保證(QoS)等。當越來越多種設備都經由home gateway連上Internet時，QoS就越顯得重要。若home gateway沒有適當的機制配合，對VoIP一類有即時資料需求的使用端會因競爭產生packet loss或jitter等影響。然而，目前大部分的home gateway尚未將QoS內建。本研究的目的即為設計並實作一具備QoS功能的home gateway。本研究假設在core network端已有Diffserv來支援由home gateway出去的封包。其面臨的困難在於找出一個有效支援QoS的queuing方法，同時此方法還要能在有限的硬體資源上實現。主要的queuing採用了CBQ，選用的原因是根據在NS2中模擬分析後得到的結果。硬體平台使用了FPGA處理封包，另連接兩張乙太網路卡。軟體部分使用了小型的embedded OS及IP stack，並加入CBQ的功能。最後也建立了一個測試環境來檢驗結果。 The broadband technologies such as ADSL have enabled delivering multimedia streams to the residential users. A home gateway is a broadband network device that provides Internet access for home equipments, including PCs, IAs (Information Appliances), and telecommunication devices. Critical issues for a home gateway have been under investigation, such as new network interface, security, resource discovery, and QoS. Without a QoS mechanism on the home gateway, packet loss and jitter can significantly affect the multimedia sessions such as VoIP. Most existing home gateways provide preliminary functions such as NAT, firewall, but they do not support QoS enable functions. This thesis designs and implements a QoS supported home gateway. The contributions of this thesis include analyzing the appropriate queuing disciplines, and implementing a CBQ engine on an embedded resource limited platform. A CBQ engine, with three queues, is implemented based on the result of our model and simulation in NS-2. This home gateway hardware is implemented on a FPGA board, with two Fast-Ethernet interfaces. An embedded OS and a light weight IP stack were adopted and modified to adapt to our QoS mechanism. Several multimedia stream application experiments are performed to validate the functionality.
