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RE: Question on Jumbo Frame support on 10 GbE

Title: RE: Question on Jumbo Frame support on 10 GbE


Is there anything in the current state of the standard that prevent Jumbo frames from being utilized? 

I mean no offense Mike so please note that this is not directed personally at you.  There would be no more of an issue with backward compatibility than there was with GigE supporting it following 100Mb...  There will always be issues such as these, when improving on deficiencies in older standards, but that is how we make progress.  

In our environment that has already been tuned with features like TCP Checksum Offloads, Large RFC-1323 scaled TCP windows, etc...  Making no other changes other than 1500 MTU -> 9000 MTU reduces our large data transfer times by ~35% with a similar drop in CPU overhead.

While there are many reasons to support Jumbo, other than a lack of knowledge of or experience with Jumbo, I have not yet been presented with *any* (IMHJ of course ;-) ) sound reason not to add it.  Deciding "since it is not there already it should not be supported", is only a self-fulfilling prophecy.  Jumbo is a great thing when used correctly (like most tools) and causes us no trouble at all.  TCP MTU discovery takes care of much of what we need, and we can work around other issues just fine.

I am not in any way implying or suggesting that it is or is not this committee's responsibility and/or scope to add it to the standard, just that it would serve the industry as a whole to not preclude the future use of Jumbo frames with on-going or future standards efforts.

Take care and thanks for all the hard work.  The stuff you folks design works wonderfully,



Corey McCormick
CITGO Petroleum Corp.

 -----Original Message-----
From:   Mike Bennett [mailto:mjbennett@xxxxxxx]
Sent:   Friday, May 18, 2001 5:07 PM
To:     Tricci So; stds-802-3-hssg@xxxxxxxx
Subject:        RE: Question on Jumbo Frame support on 10 GbE


Jumbo frames (with the exception of 1522 bytes for vlan tags) are not
specified in any 802.3 standard.  There would have been a serious problem
with backward compatibility with other than 10 GbE equipment if we had
included support in 802.3ae.  Since jumbo frames would have to have been
standardized throughout 802.3 it was declared outside the scope of 802.3ae.



Mike Bennett
Lawrence Berkeley National Lab

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of Tricci So
Sent: Friday, May 18, 2001 11:40 AM
To: stds-802-3-hssg@xxxxxxxx
Subject: Question on Jumbo Frame support on 10 GbE

Hi all,

If my understanding is correct, the support of Jumbo Frame is not currently
within the scope of 10GbE.  May I ask what is the rationale behind this

Many thanks in advance for your help....
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