On Saturday, April 15, 2006 02:05:52 PM +0200 Harald Barth
<[EMAIL PROTECTED]> wrote:
While tracing a one-way performance problem with our AFS server (MTU
1500), I found that on the client side (MTU 8000), every few packets it
tried to send a jumbogram, overriding the negotiated MTU of 1500.
* rx can pack more than one rx message into a datagram.
* rx can make datagrams > MTU.
Both these "features" have been called jumbogram. I think
the second one is not making things better with todays
computers (fast enough CPUs) and network structure
(fragmentation and MTU discovery often broken).
And to make matters worse, _neither_ of them is what people outside the AFS
community mean when they say "jumbogram". Those people are referring to
the practice of using "oversized" ethernet packets, such as the original
poster's interface MTU of 8000 octets. That practice _can_ be beneficial,
as long as such oversized packets are used only when the path MTU is
actually that large.
-- Jeffrey T. Hutzelman (N3NHS) <[EMAIL PROTECTED]>
Sr. Research Systems Programmer
School of Computer Science - Research Computing Facility
Carnegie Mellon University - Pittsburgh, PA
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