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[H-source-users] Ethernet flow control


From: Luis A.
Subject: [H-source-users] Ethernet flow control
Date: Sun, 30 Mar 2014 14:45:30 -0600

Hi!,

I've been using and building some LTSP systems now, and  i have found
some hardware/standard issue that is somehow problematic.

I'm talking about the flow control on the Ethernet NICs, this is a not
so good feature of the TCP/IP protocol (802.3x), that would tell the LAN
neighbor that it's getting more data that it can process, so it sends a
pause signal to the sender to stop sending data.

This is mostly experienced on mixed networks that has 100 Mbps and
Gigabit devices on it, forcing the Gigabit speed down to 100 Mbps.

This feature can be disabled on managed switchs (which are really
expensive) or on the network card directly, but there is very few
information about the network cards that support control flow disabling.

So i'm here asking for your kind collaboration to identify those cards.
The tool used to disable flow control on the networkcard is ethtool, and
the command is, 

sudo ethtool -A eth0 autoneg off rx off

where, eth0 is the gigabit network card adapter, it would tell you if
your card is supported or not to disable flow control.

If you could add this info to h-node site it would be even better,
thanks again for your cooperation and time.

-- 
Luis A. Guzmán García
¡Se Libre! - http://fsfla.org/selibre
The Hardware Database Project - http://www.h-node.org
GPG Key: EB153FAF

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