[95965] in North American Network Operators' Group
Re: Thoughts on increasing MTUs on the internet
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Thu Apr 12 11:42:58 2007
In-Reply-To: <20070412132649.1C1CC766653@berkshire.machshav.com>
Cc: NANOG list <nanog@merit.edu>
From: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Thu, 12 Apr 2007 17:32:35 +0200
To: "Steven M. Bellovin" <smb@cs.columbia.edu>
Errors-To: owner-nanog@merit.edu
On 12-apr-2007, at 15:26, Steven M. Bellovin wrote:
> Last I heard, the IEEE won't go along, and they're the ones who
> standardize 802.3.
I knew there was a reason we use ethernet II rather than IEEE 802.3
for IP. :-)
> A few years ago, the IETF was considering various jumbogram options.
> As best I recall, that was the official response from the relevant
> IEEE folks: "no". They're concerned with backward compatibility.
Obviously keeping the same maximum packet size when moving from 10 to
100 to 1000 to 10000 Mbps is suboptimal. However, if the newer
standards were to mandate a larger maximum packet size, a station
connected to a 10/100/1000 switch at 1000 Mbps would be able to send
packets that a 10 Mbps station wouldn't be able to receive. (And the
802.3 length field starts clashing with ethernet II type codes.)
However, to a large degree this ship has sailed because many vendors
implement jumboframes. If we can fix the interoperability issue at
layer 3 for IP that the IEEE can't fix at layer 2 for 802.3, then I
don't see how anyone could have a problem with that. Also, such a
mechanism would obviously be layer 2 agnostic, so in theory, it
doesn't step on the IEEE's turf at all.
