Re: [Aoetools-discuss] Ethernet CRC-32 and Data integrity?

[Hilko B. <be...@hi...>]

* Adi Kriegisch:

> I think I did not get the question. What error point do you introduce
> using a switch?

A common setup uses a Switches to fan out a number of tagged VLANs from
a trunk port to multiple untagged port-based VLANs. In such a setup, the
switch has to add or remove VLAN tags and thus recalculate the CRC32
frame check sequences for almost every frame.

An error that might occur after the switch has verified the FCS for a
received frame and before it has sent out the modified frame can not be
detected by the receiving NIC. 

I have seen symptoms that could be explained by this in an AoE setup
with "cheap" (~100€/8 ports) switches that did not handle the
combination of high load and a tagged/untagged VLAN setup particularly
well.

Cheers,
-Hilko