netdev - Re: e1000 driver problems

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.0712041043520.15251@tesla.psc.edu>
Date:	Tue, 4 Dec 2007 11:02:23 -0500 (EST)
From:	Matt Mathis <mathis@....edu>
To:	Lukas Hejtmanek <xhejtman@....muni.cz>
cc:	NetDev <netdev@...r.kernel.org>
Subject: Re: e1000 driver problems

This is probably not an e1000 problem, but a general Ethernet "feature".  If 
you defeat auto-negotiation to force the data rate, you implicitly defeat 
duplex negotiation as well.  You need to explicitly set the duplex mode.

In full duplex mode, send and receive are are fully independent, and packets
can flow concurrently in both directions.

In half duplex mode the receiver assumes it is hearing its own transmission, 
and ignores (or errors) frames that are partially overlapped by it's 
own transmission.

See for example: S. Shalunov and R. Carlson. "Detecting Duplex Mismatch on 
Ethernet"
http://www.springerlink.com/content/vapet12x584e6wyn/

Best regards,
--MM--

On Tue, 4 Dec 2007, Lukas Hejtmanek wrote:

> Another problem at my own machine. If I force speed to 100Mb on 1GE network,
> I can reach 95Mbps bidirectional using UDP (0.34% loses) but only 1.2Mbps
> using TCP. A bug? If I enable autonegotiation and run at 1GE, I can got 95Mb
> on TCP to the target machine (the target machine has only 100Mb connection).
>
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html