Wireless Access

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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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  • 1.  MTU issure

    Posted Dec 08, 2015 09:15 AM

    Hi guys,

     

    How does the layer 2 switch process the packet when the packet is bigger than the MTU of the switch's interface?

    There are 2 situations:

    1, How does the layer 2 switch process the ingress packet.

    2, How does the layer 2 switch process the egress packet.

     

    For the first question, I'm sure we all know the answer. And it proves that the layer 2 switch would check the FCS field of the frames, because the layer 2 switch would drop the frame whose size is bigger the MTU of the interface.

     

    But how would the switch act if the interface's MTU are different?

    MTU.jpg

     

    I asked another question about this, and thanks to Armand Wang,what  I really should ask.

    Like the Pic above, How does the switch's port 2 process the packet port 1 received a frame whose size is bigger  than the Port 2's MTU?



  • 2.  RE: MTU issure
    Best Answer

    Posted Dec 08, 2015 01:19 PM

    In my experience, it would depend on the switch, and the way the software on it is written.

     

    Most I've worked with check MTU on ingress, and not egress.

     



  • 3.  RE: MTU issure

    Posted Dec 09, 2015 07:34 AM

    I did the experiment today, and the result just liked the Pic shown.

     

    So it should be like the way you said. Only check the ingress, and don't check the egress.