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Wireshark-users: Re: [Wireshark-users] jumbo frames

From: "hans.loepfe" <hans.loepfe@xxxxxxxxxx>
Date: Sun, 16 Jul 2006 16:29:39 +0200
Hi Bruno

check for TCP frames larger than 1454 bytes on wire.
These must be Jumbo Frames, because TCP by default has a max size 1454
bytes.
If you don't find any larger than that value, Jumbo Frames is not enabled at
one of the devices involved during the transmission.
Check your NIC's and the Switch or Router your are using, that they support
Jumbo Frames and that the option is enabled.
Some devices allow various JB Frames settings (sizes). During transmission
the devices will try to agree on the common minimum size avaialble to all
devices involved.

So if one NIC is set to 7K Jumbo Frame size and the other supports 9K JBF
size, then they will use 7K max.
If in this case the Switch (router) does not support JBF then the default
TCP frame size value 'should' be agreed upon.
Though some devices cannot do that, hence such a configurtation might end up
in a chaos with lots of retransmitts or in other words decreased
transmission performance.

Jumbo Frames is not standardized thus the implementation for each device
involved may vary quite a bit - causing a headache.

Hope this helps.



-----Ursprungliche Nachricht-----
Von: wireshark-users-bounces@xxxxxxxxxxxxx
[mailto:wireshark-users-bounces@xxxxxxxxxxxxx]Im Auftrag von bindz
Gesendet: Sonntag, 16. Juli 2006 03:37
An: wireshark-users@xxxxxxxxxxxxx
Betreff: [Wireshark-users] jumbo frames


Hi gurus,

I'm capturing frames from a mirror port and I was very confident that I
would find jumbo frames, I recompiled wireshark from sources (latest
release) in a Fedora 5 "penguin" can anyone confirm me that I am able to
capture this type of traffic, or at least point me some directions.

Best Regards,
Bruno Fernandes
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