NEXUS 5548

Posted on 2014-11-23
Last Modified: 2014-11-23
How do non Layer 3 devices such as l2 switches deal with MTU issues.
Question by:sectel
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Expert Comment

by:Don Johnston
ID: 40461042
You're going to have to provide more information.

The title of "Nexus 5548" gives no information as to what you're looking for.

How do non Layer 3 devices such as l2 switches deal with MTU issues.
What do you mean by "MTU issues"?  For most Layer 2 switches, the default MTU is 1500 bytes. Frames larger than that are discarded.

Author Comment

ID: 40461063
Today's networks are jumbo capable (9216) ....hence part of a network could be jumbo capable and another portion may only provide 1500 MTU capability.

What happens when a jumbo frame crossed the boundary and egresses a  L2 switch that can only pass packets that are 1500 bytes of smaller.  

The Switch would then have to fragment the packet..  Since l2 switches don't look at the l3 header how does the fragmentation work out.
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Expert Comment

by:Don Johnston
ID: 40461072
If a layer 2 is not configured for jumbo frames, it will just discard any frames larger than 1518 bytes.

Author Comment

ID: 40461076
So your saying a l2 switch will not fragment....correct?
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Accepted Solution

Don Johnston earned 500 total points
ID: 40461080

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