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Re: [HSSG] Topics for Consideration: Jumbo Frames


Hi Arthur,

there is a nice little "tutorial" about the Pros and Cons
of jumbo frames at,
it also includes actual frame size distribution measurement on the
MCI backbone from 1998 in which you can see that there are a lot
of frames >1500B from FDDI and other sources, they mention that
more than 50% of all traffic (measured in Bytes and not in packets)
come from packets >1500B. But, larger packets also have a clear
benefit to TCP/IP performance. The difference in store-and-forward
latency between 1.5kB and 9kB is negligible at higher speeds, time
of flight is much, much higher ...


Arthur Marris wrote:
Joel, Mike,
   Don't jumbo frames increase latency in links where there is store and forward?

Both my position and that of the customers I deal with is that higher speeds, 10gbps included, is more efficient with the larger packets.
no argument from me on this one, although the actual efficiency gained comparing 1.5 K frames to 9 K frames is only ~ 2%, but when you're on the cutting/bleeding edge of technology, every bit counts.


Marcus Duelk
Bell Labs / Lucent Technologies
Data Optical Networks Research

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