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Re: Ethernet NAPs (was Re: Miami ...)

  • From: Miquel van Smoorenburg
  • Date: Thu Aug 23 11:17:25 2001
  • Distribution: cistron
  • Newsgroups: lists.nanog

In article <[email protected]>,
RJ Atkinson  <[email protected]> wrote:
>At 10:18 23/08/01, John Kristoff wrote:
>>Certainly.  In a nutshell, it might be best to take steps to avoid
>>fragmentation elsewhere in the network.  Perhaps a rule of thumb that
>>should be stressed is to use jumbo frames if you know for sure the other
>>end system(s) support it, otherwise default to 1500.
>Or just use Path MTU Discovery.  

Ofcourse, for path MTU discovery to work, a router must know that the
outgoing link has a smaller MTU than the packet so that it can send
back an ICMP error to the sender.

On a GigE interface with jumbo frames where the other side on the
same ethernet might not support jumbo frames that is probably not
the case. The packet will simply get dropped and the sender will
never know why it was dropped.

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