----------------eredeti üzenet-----------------
Feladó: "Alexandre" <alxgomz@gmail.com>
Címzett: "PongráczI" <pongraczi@pongraczistvan.homelinux.com>
CC: "aoetools-discuss lists.sourceforge.net" <aoetools-discuss@lists.sourceforge.net>
Dátum: Sat, 6 Apr 2013 10:57:22 +0100
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Oh are you talking about iSCSI Digest?
 
If so I recommend you read this (only the the chapter should be enough to shced a ligth):
http://www.jdsu.com/ProductLiterature/Understanding-iSCSI-Digests-white-paper-30162803.pdf

 
To make the long story short, iSCSI digest is meant to protect against errors during protocol transitions on the hosts, which are highly used in iscsi ([data]/iSCSI-> TCP -> IP -> Ethernet) while aoe only uses ethernet as a carrier so is far less prone to this kind of error.

 
Moreover, the overhead introduced by digest seems to have lead people to disable it in most cases (most initiators disable it by default, and the document states that it is known to be a common practice in the iscsi world). Instead, integrity is ensured by Etherne qnd IP checksums (whle AoE only needs to check the Ethernet CRC).

 
If you're talking about another mechanism please let us know.
 


 

Alexandre, thank you for your valuable answer! Good to know, iscsi in practice has a good protection, which commonly disabled, great :)

So, as I checked the Layer2, it has error checking as you wrote. So, as I understand now, data corruption cannot happen on layer2, because this basic CRC protection handle layer 1 issues which can happen in the physical layer.

István