Wireshark-users: Re: [Wireshark-users] 8-10% packet error/loss is normal wired network?
From: Shawn T Carroll <[email protected]>
Date: Thu, 12 Jul 2012 14:20:13 -0700 (PDT)
+1.  And, for what it's worth, just hearing that the value of packet loss was 8-10% made it sound to me like a duplex mismatch was at fault, though this varies with the data rate and the direction that of the traffic (it's the full to half direction that causes collisions and loss)

Shawn


From: Kok-Yong Tan <[email protected]>
To: [email protected]
Sent: Thursday, July 12, 2012 5:15 PM
Subject: Re: [Wireshark-users] 8-10% packet error/loss is normal wired network?

On 7/11/12 15:56, Flako wrote:
>
> Hello Prigge, Jim
> The printer is at 100Mb / s FULL with autonegotiation disabled, the
> desktop was as 1Gb / s FULL with autonegotiation enabled.
> The swicth A (100Mb / s) and B (1Gb / s) are connected directly to each other.
>
>
> Now connect the Desktop Printer and a switch C (only two), then swich
> C connects directly to swicth A.
> I'm sniffer on the Desktop to see differences and discard things. I
> tell them when finished.
>
> Thank you for writing so far.
> (Examples of how to find a fault will serve me now or the next)
>

Are your statements above accurate (printer has autonegotiation *DISABLED* and desktop has autonegotiation *ENABLED*)?  Both devices *MUST* match, even if one has autonegotiation enabled.  i.e., If the desktop has autonegotiation enabled, then the printer *MUST ALSO* have autonegotiation enabled.  Otherwise autonegotiation will fail and the device with autonegotiation enabled will drop down to half duplex.  See this:

<http://en.wikipedia.org/wiki/Duplex_mismatch#Duplex_mismatch_due_to_autonegotiation>

Hansang Bae mentioned this in a session at a prior Sharkfest during one of his very illuminating "Deep Dive" packet analysis sessions.

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