[15054] in North American Network Operators' Group
Re: MTU of the Internet?
daemon@ATHENA.MIT.EDU (Per Gregers Bilse)
Fri Feb 6 08:18:33 1998
From: Per Gregers Bilse <pgb@EU.net>
Date: Fri, 6 Feb 1998 13:50:27 +0100
In-Reply-To: <19980205204529.32468@blackrose.org>
To: nanog@merit.edu
On Feb 5, 20:45, "Dorian R. Kim" <dorian@blackrose.org> wrote:
> > 512 544 576 1024 1536 2048 2560 3072 3584 4096 4608
> > .010 .006 .120 .000 .099 .197 .000 .000 .000 .000 .000
> >
> > It's been up for some weeks and the sample size is, well, OK. As
> > expected, large number at the low end, but I'm not sure what to think
>
> Bug. I believe counters a shifted by one slot from 1024. As you'll note
> that that slot is empty.
Yes, that's what one would suspect, but it's been like that ever since
flowswitching was first introduced (which, of course, doesn't
necessarily mean anything). In any case, the interesting part is that
30% of all packets would still be larger than 576, with probably close
to 20% being larger than 2*576, meaning that an "enforced" MTU of 576
would lead to a very substantial increase in packet count. This would
be a big step in the wrong direction. (On that note, I'm actually not
sure about the wisdom of MTU discovery in the Internet, given the large
number of dial-up users. The way to go is to send big packets and
fragment in the access server if the user has negotiated a small MRU.)
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