請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/18990
標題: 以交換式以太網路為基礎實現IP交換技術之架構
IP Switching over EtherSwitch Architecture
作者: 劉俊吉
Liu, Jiun-Ji
關鍵字: Ethernet
以太網路
Switch
Router
Trunking Protocol
交換器
路由器
並聯式連線
出版社: 資訊科學學系
摘要: 交換式以太網路是一個架構簡單又高速的第二層的交換技術,適用於單一 網域,當網路的流量要跨越網域時,就必須經過路由器。路由器的速度很 慢且速度上難以改進,成為網路上的瓶頸。IP交換技術是一個突破性的技 術,以Cut-through的技巧在ATM的硬體環境上結合IP來實作,取代了傳統 的路由器,然而ATM是非常昂貴的設備且市場佔有率極低。我們認為IP交 換技術的概念可以在現在最廣泛使用且技術成熟的以太網路上實作,我們 提出了一個以交換式以太網路為基礎實現IP交換之技術(IP Switching overEtherSwitch, or IPS/ES),並對這個方法做了電腦模擬與效能分析 。我們的方法是讓以太網路交換器結合了第三層的功能,再以建立資料流 的方式達到第三層的Cut-through,讓第三層的網路流量可以用第二層的 交換技術來高速的傳遞。我們定義了一套IPS/ES交換器之間的通訊協定來 建立資料流,同時我們討論了IPS/ES交換器與傳統交換器或路由器之間互 相溝通的方式,提出了可行的相容方案。在這類的網路中,我們常常會需 要並聯數個連線來增加可使用的頻寬,這些並聯的連線在邏輯上可以視為 視同一個連線。這種情況必須有特定的軟體來支援,才能有良好的運作。 目前IEEE 802 Community正在制定一個關於Vendor-interoperable TrunkingProtocol(並聯式連線通訊協定)的標準,但截至現在尚未有它 的草稿發表。一般而言,有兩類方法來實作,一類是在Trunking Link上 傳送的封包額外加上Label,這個Label可能包含封包順序的資訊,在 Trunking Link的兩端必須都了解這樣的通訊協定﹔另一類是在Trunking Link上傳送的封包不額外加上Label。基本上,我們認為不額外加上Label 是比較好的策略。我們提出了一個不額外加上Label的可行方法,稱為 Trunking Table Algorithm。它是在盡量避免資料流改變路徑的情況下, 來做到並聯式連線的負載平衡。然後我們對這個方法做了電腦模擬與分析 。最後我們討論了我們提出的並聯式連線通訊協定在IPS/ES的架構下,提 出如何整合的方案。
The randomness nature of the network traffic patterns have turned the routerinto the bottleneck in the network infrastructure. IP switching, which usescut-through technique over ATM hardware and routes IP traffic, is atechnology breakthrough to enhance the performance of a router. Nevertheless, the ATM hardware is expensive and has a low market share. Wepropose to implement the concept of IP switching over the lower-cost andmature Ethernet switching technology. The resulting structure is called "IPswitching over EtherSwitch, or IPS/ES."IPS/ES puts layer three routing into an EtherSwitch and utilizes layer threecut-through by identifying flows. As a result, layer three traffic can beforwarded by layer two switching hardware with a high speed. We define aprotocol for neighboring IPS/ES switches to identify a flow and create acut- through path for it. The problems of compatibility between IPS/ ESswitches and traditional routers/switches are discussed and solutions areprovided as well.To reduce upgrade cost, the user might want to connect two switches/routerswith multiple lines when more bandwidth is needed. These parallelconnections are called Trunking Links. We can regard trunking links as onelogical connection. However, for this approach to work well, load balancingneeds to be provided for the parallel links while maintaining the order oftraffic flow. Currently, IEEE 802 community has an effort to standardize avendor-interoperable trunking protocol, but no result has come out of thecommunity yet. Generally speaking, there are two kinds of approaches fortrunking links. One approach adds an additional label that includes sequenceinformation to the packet. With this approach, both sides of switches musthave some agreed upon protocol for buffering and packet resequencing; theother does not use any additional labels. However, the conventionalapproaches that does not use labels, such as Modulo-N Hash, cannot achieveload balancing and maintain path consistency at the same time.We come up a trunking protocol called "Trunking Table Algorithm," which doesnot use any label and incurs much less path disruption to maintain thesequential delivery of data. Simulations show that Trunking Table Algorithmprovides a better load balance with minimum path changes for flows. The wayto apply the trunking protocol into IPS/ES is also discussed.
URI: http://hdl.handle.net/11455/18990
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