> There are all sorts of people spouting all sorts of lies around Windows
> newsgroups about why small MTUs are good; I think novice users are simply
> getting drawn in by supposed experts.
Such as?
I don't think it's an issue of lies about why small MTUs are good, but the
fact that if joe random user is told "576 is good", then they assume that
anything different is _bad_. We all know that there's good reasons for all
sorts of different MTUs, mainly because of the different types of traffic you
could have - there's always going to be a tradeoff between efficient transfer
of large blocks of data and immediaecy (sp?) of response time. The problem with
anything Microsoft may put forth is that it'll read like "576 is good. It is
the best. We do it. So should everybody. If 576 is good, all else must be
bad." And that's simply not the case.
eric
Somehow this has become a MS bashing thread (gee, imagine that), but from
personal experience it is not only Windows that experiences MTU issues.
Don't ask me why or how it was happening, but about a year ago I had a
Frame T-1 that the only way I could get it to work was to set my routers
MTU to no higher than 1476 and then every machine on the network had to
have an MTU of one less than the router or they could not get past it.
My assumption was that the issue was with my router (a Linux box with a
SDL csu board), but once I figured out a way around the problem I just
fixed it and didn't worry about it.
The only point to that was just an FYI, beyond that I have noticed what
appears to be a general "Internet-wide" issue lately where smaller packets
have much less trouble than larger packets, obviously adjusting your MTU
downwards in that situation has benefits.
What I would like to know is: is there a MTU that is best to use IN
GENERAL, or should we all just trust discovery and live with it?
Ron
---------------- Ronald J. Fitzherbert, President ---------------
Flying Penguin Productions Limited
Arlington, Virginia & Austin, Texas (USA)
-------------------- http://www.penguin.net/ --------------------
Eric Osborne <osborne@notcom.com> writes:
We all know that there's good reasons for all sorts of
different MTUs, mainly because of the different types of
traffic you could have - there's always going to be a
tradeoff between efficient transfer of large blocks of
data and immediaecy (sp?) of response time.
I know no such thing. My understanding of MTU is that the
Maximum Transmission Unit indicates the largest IP
datagram a logical transport medium is able to carry
without fragmentation.
There are, however, reasons why one might choose to send a
datagram (which may contain a TCP segment or some other
traffic) at smaller sizes than the transport medium or
media may support.
Sean.
Ron Fitzherbert <ron@penguin.net> writes:
What I would like to know is: is there a MTU that is best to use IN
GENERAL, or should we all just trust discovery and live with it?
MTUs should reflect the largest datagram size transport
media can carry, period.
Small MTUs, whether by design or configuration,
limit the flexibility of end systems in choosing to send
appropriately large datagrams without introducing
IP fragmentation.
Sean.