[132206] in North American Network Operators' Group
RE: mtu question
daemon@ATHENA.MIT.EDU (Brandon Kim)
Wed Nov 17 16:57:18 2010
From: Brandon Kim <brandon.kim@brandontek.com>
To: <nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org>
Date: Wed, 17 Nov 2010 16:57:13 -0500
In-Reply-To: <20101118081810.0675996b@opy.nosense.org>
Cc: nanog group <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Thanks for the 411 Mark!
Again=2C this NANOG list is such a valuable source of info and knowledge!
> Date: Thu=2C 18 Nov 2010 08:18:10 +1030
> From: nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
> To: brandon.kim@brandontek.com
> CC: jbates@brightok.net=3B deric.kwok2000@gmail.com=3B nanog@nanog.org
> Subject: Re: mtu question
>=20
> On Wed=2C 17 Nov 2010 16:23:54 -0500
> Brandon Kim <brandon.kim@brandontek.com> wrote:
>=20
> >=20
> > Jack brings up a good point. MTU is basically pointless since packets n=
ever traverse any real interface.......
> > So in theory the size can be anything...
> >=20
> >=20
>=20
> Not quite. You hit packet length field limits. IPv4 packets can't be
> larger than 65535=2C and IPv6 packets also can't be larger than 65 576
> (40 byte IPv6 header + 2^16 payload)=2C unless the jumbograms and the
> jumbo payload extension header is supported. Last time I checked=2C by
> setting the loopback MTU > 65 576=2C Linux=2C for example=2C doesn't supp=
ort
> the jumbo payload extension header (or if it does=2C I didn't spend
> enough time finding out how to switch it on - a very large MTU didn't
> trigger it).
>=20
> That being said=2C with a 64K MTU on loopback=2C you can legitimately cla=
im
> to get >10Gbps at home=2C as long as you don't mention how you're doing
> it =3B-)
>=20
> Regards=2C
> Mark.
=
