[Cialug] Basic Networking ARP and Routers

[Zachary Kotlarek]

On Jul 24, 2014, at 1:43 PM, Nick Graber <nick at graber.me> wrote:

> Oh,  I forgot to ask if it was an issue that the Ethernet frame check
> sequence was incorrect?
> 
> Sample ARP summery from wireshark:
> 1 0.000000000 Schniede_10:ea:16 Broadcast ARP 64 Who has 172.20.87.235?
> Tell 10.1.88.250 [ETHERNET FRAME CHECK SEQUENCE INCORRECT]


That’s usually nothing. The FCS comes out wrong for a whole variety of reasons, including the underlying hardware simply not providing the FCS to the higher layers or appending data that wasn’t actually on the wire. With most hardware if the FCS was *actually* wrong on the wire the frame would not be delivered to Wireshark in the first place.

You can disable validating the FCS to suppress the warnings.

	Zach

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