Module 5: Switches  
5.1 LAN Design 
   
5.1.1 LAN design goals  
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5.1.2 LAN design considerations 

As seen in Figure , enterprise servers should be placed in the main distribution facility (MDF). Whenever possible, the traffic to enterprise servers should travel only to the MDF and not be transmitted across other networks. However, some networks use a routed core or may even have a server farm for the enterprise servers. In these cases, network traffic travels across other networks and usually cannot be avoided. Ideally, workgroup servers should be placed in the intermediate distribution facilities (IDFs) closest to the users who access the applications on these servers. This allows traffic to travel the network infrastructure to an IDF, and does not affect other users on that network segment. Layer 2 LAN switches located in the MDF and IDFs should have 100 Mbps or more allocated to these servers.

由圖 可知，企業伺服器應該要放置在主要配線設施(MDF)中， 要儘可能的讓送往企業伺服器的流量只送到MDF而不要跨越到其他網路， 然而，有些網路運用核心路由或以伺服器群的方式建置企業伺服器， 在這種狀況下，通常無法避免跨越網路的流量。 工作群組伺服器在理想狀況下應該放置在靠使用其應用程式之用戶最近的中介配送設備(IDF)中， 這樣可以讓網路流量送往IDF且不會影響在同一個網路區段的其他用戶， 在MDF及IDF中的第二層交換器必須提供100Mbps或更高的速度給這些伺服器。

5.1.3 LAN design methodology 
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5.1.4 Layer 1 design 
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5.1.5 Layer 2 design  
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5.1.6 Layer 3 design 
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5.2 LAN Switches 
   
5.2.1 Switched LANs, access layer overview 
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5.2.2 Access layer switches  
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5.2.3 Distribution layer overview  
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5.2.4 Distribution layer switches 
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5.2.5 Core layer overview 
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5.2.6 Core layer switches 
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