從搜索效率看二層網絡與三層網絡的本質區別

龐文堯

摘要： 二層網絡以交換機為交換設備，以MAC地址表為搜索依據，其搜索次數很大。三層網絡以路由器和交換機聯合作為交換設備，其中路由器以路由表為搜索依據，將廣播域進行了分割，綜合搜索次數大大降低，從而使大型網絡的地址搜索時間減少到可接受的范圍。本文通過詳細的分析，比較了以交換機為主的二層網絡和以路由器為主的三層網絡之搜索差別，從而揭示二層網絡和三層網絡的本質差別。

關鍵詞： 交換機； 路由器； 二層網絡； 三層網絡； 搜索效率

中圖分類號：TP393.0文獻標志碼：A文章編號：1006-8228(2012)09-39-02

Essential difference between the two-layer network and the three-layer network due to search efficiency

Pang Wenyao

（Zhejiang University City College, School of Information & Electrical Engineering, Hangzhou, Zhejiang 310015, China）

Abstract： The two-layer network uses switch as switching equipment according to the MAC address table which requires a large number of searching times. The three-layer network uses router and switch together. The router splits the broadcast domain and searches the networks based on routing table, so that the total number of searching times are reduced to an acceptable range. The difference of searching times between two-layer switch-based network and three-layer router-based network is compared and their essential difference is revealed.

Key words： switch； router； two-layer network； three-layer network； search efficiency