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Re: MTU path discovery and IPSec

  • From: Joe Maimon
  • Date: Thu Dec 04 16:46:24 2003



Tony Rall wrote:

On Wednesday, 2003-12-03 at 09:38 PST, David Sinn <dsinn@dsinn.com> wrote:


<snipped>

(And note that frag 1 often is not the first fragment to arrive at downstream nodes. In my example in (1), frequently frag 2 will reach places before frag 1 does (if any router along the path reorders its transmit queue based on packet size).)


I agree with all I have snipped.
I was wondering would it not be wiser for fraggers to frag in half instead of just the overflow?

For instance, suppose router has to fragment 1500 byte packet to go over 1476 GRE. Instead of having a big packet/little fragment why not just divide in half?
This would give them more equal buffer treatment, but an even bigger potential win is to avoid perhaps a second (maybe ipsec?) fragmenting later on down the pipe.

Once you are going to do it, do it right. It is not as if your decreasing header overhead by producing small fragment packets. And I am assuming the whole packet is already in buffer when it comes time to fragment it.

Tony Rall