Corey:
Please
see below:
-----Original
Message-----
From: McCormick,
Corey [mailto:Corey@xxxxxxxxx]
Sent: Friday, May 18, 2001 4:18
PM
To: Mike Bennett; Tricci
So; stds-802-3-hssg@xxxxxxxx
Subject: RE: Question on Jumbo Frame
support on 10 GbE
Mike,
Is there anything in the
current state of the standard that prevent Jumbo frames from being
utilized?
Well, technically yes since we agreed to keep MaxFrameSize
at 1518 octets.
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.
None
taken.
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.
The
question is why would we need to standardize jumbo frames? The reason would be so we can
reasonably assured that if vendors comply with the spec, there would be no
interoperability problem when using jumbo frames. In your environment, do you run jumbo
frames between different vendor’s equipment? While I haven’t personally done
interoperability testing for that feature I would be very surprised if there
is an interoperability issue there now.
The next question is in which standard do we include them? 802.3ae (too late now I believe)?
Previous versions (not even sure how we do that, perhaps a maintenance
revision)? Now, I agree that none
of these questions raise a sound technical reason not to do it, but there are
logistical reasons why it may not be worth the effort to do it. One technical point, albeit a minor
one these days, is that bridging between a segment that is not jumbo-frame
enabled and one that is puts additional burden on the bridging/switching
device to fragment the frames at a 6:1 ratio in the case of a 9K
framesize. Nonetheless, if there
really is a strong feeling that jumbo frames should be standardized, then
someone should do a Call For Interest to have a jumbo frames study group to
see if there is enough interest to standardize the frames for all of
Ethernet.
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.
As far
as I know, every time there is a new Ethernet standards activity the issue is
raised and so far has not made its way into the standard. I’m sure it will continue to be
raised, but I don’t believe it will get support unless it is proposed to be
done for all Ethernet standards. It’s a pleasure to discuss
this, but I’m going to let it die on the reflector, as it doesn’t pertain to
the completion of the 802.3ae standard.
Best
Regards,
Mike
Take care and thanks for
all the hard work. The stuff you folks design works
wonderfully,
Sincerely,
Corey
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
Tricci:
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.
Regards,
Mike
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
intent?
Many thanks in advance for
your help....
Tricci
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