How L3 switching works.

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Jul 10th, 2007
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Hi Guys,

I am little bit confused about the term layer 3 switching i.e hardware based routing.can anyone explain or proivde a link which explains this.



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Jon Marshall Tue, 07/10/2007 - 23:32
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Hi Mahmood

Layer 3 switching as you say is routing done in hardware as opposed to software. Generally speaking a router will route packets in software ie. the intelligence to make the routing decision is contained within the IOS code.

A layer 3 switch however has dedicated ASIC ( Application Specific Intergrated Circuits ). These are a bit like the CPU of your PC except that they are specialized in what they do and hence more effecient. On a L3 switch it these chips that route the packets.

TO be honest you have pretty much summed up the major difference in your question and L3 switching was used primarily as a marketing term when it originally came as everybody knew Layer 2 switching was fast and routing was slow.




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