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Thread: difference between Layer 3 switch and Router

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    Default difference between Layer 3 switch and Router

    Dear All.

    Does anybody know what is difference between Layer 3 switch and Router ?

    I want technical answer.

    sorry for out of topic question.

    Regards.
    Puppen
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    Is that all you got? rockdalinux's Avatar
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    Default

    Layer 3 switch are almost same as a router with following differences
    Layer 3 switch is optimized to data as fast as layer2 switch but it makes the decision on how to transmit traffic at layer 3 (just like a router)

    Perfect in Lan environment as it is built on switching hardware. Another thing is it is faster than a router in LAN environment. Layer 3 use route once switch many policy. It means when it search for specific destination using a routing table, it creates a cache entry in a switch RAM. So next time it does not have to search again for a routing table for same source and destination address. It also picks up hop information from cache.
    So you can say that Layer 3 switch has the ability to reprogram the hardware dynamically with the current Layer 3 routing information. That is why it is faster than a router.

    To be frank many of Cisco’s layer 3 switch’s are actually routers

    Layer 3 switch good for LAN

    Routers good for WAN

    Router has some advanced routing functionality which is not available in Layer 3 switch at all.

    For more info see: http://www.foundrynet.com/services/f...ingRouter.html
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    The main difference is how an IP packet is routed using a router or Layer 3 switch.
    According to Cisco: the process of routing an IP packet can be divided into two distinct processes:

    => Control plane
    => Data plane

    A traditional router uses the same general purpose CPU used to perform control plane operations to also implement data plane operations, meaning data plane operations are handled in software. A Layer 3 switch on the other hand uses an ASIC to perform data plane operations because it is very easy to program the very simple operations required for the data plane into an ASIC. In this respect, the data plane is implemented in hardware because a series of hardware operations are programmed into the ASIC that perform the data plane operations required for routing a packet.

    If you don’t understand Control plane/ Data plane then I recommend studying following URL (above text is actually copied from same url):

    http://www.ciscopress.com/articles/a...?p=102093&rl=1

    Hope this helps.

    PS:I think we need separate forum for networking discussion. Right now it is Linux only thingy. I hope vivek will add it sooner or later.

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    Never say die nixcraft's Avatar
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    Default

    In lay mans language:
    * A router may have more functions than a layer 3 switch like filtering, wan stuff, advanced routing options etc etc
    * Generally a layer3 switch will route traffic between two subnets only

    Tom / puppen ====> Ok I will create another sub-forum here to discuss networking related issues and I will move this topic.
    All [Solved] threads are closed by mods / admin to avoid spam issues. See Howto mark a thread as [Solved]


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    Done

    Topic moved to Computer Networking and Internet/broadband discussions. If you guys need other sub forum ping me back

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    Default Physical implementation

    Tom you are right and URL is also correct. To sum up I can say:

    1) ROUTER : In general-purpose routers, packet switching takes place using a microprocessor.

    2) LAYER 3 SWITCH: In a Layer 3 switch performs this using application specific integrated circuit (ASIC) hardware

    This is the major difference between the packet switching operation of a router and that of a Layer 3 switch is the physical implementation.

    Topic moved to Computer Networking and Internet/broadband discussions. If you guys need other sub forum ping me back
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    @monk, done as per your suggestion

    … Stay tuned for new changes, sooner or later I will upgrade this forum to PHPBB v3.0. Once software upgraded, forum will automatically redirect all of you to new url/location forum.cyberciti.biz.
    All [Solved] threads are closed by mods / admin to avoid spam issues. See Howto mark a thread as [Solved]


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