From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Hutchings <bhutchings@solarflare.com>
Subject: Re: [PATCH v3] Net-ethtool : Allow ethtool to set interface in
 loopback mode.
Date: Wed, 01 Dec 2010 20:17:03 +0000
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Cc: David Miller <davem@davemloft.net>,
	linux-netdev <netdev@vger.kernel.org>,
	laurent chavey <chavey@google.com>
To: Mahesh Bandewar <maheshb@google.com>
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On Wed, 2010-12-01 at 12:14 -0800, Mahesh Bandewar wrote:
> This patch enables ethtool to set the loopback mode on a given
> interface. By configuring the interface in loopback mode in conjunction
> with a policy route / rule, a userland application can stress the egress /
> ingress path exposing the flows of the change in progress and potentially
> help developer(s) understand the impact of those changes without even
> sending a packet out on the network.
> 
> Following set of commands illustrates one such example -
>    a) ip -4 addr add 192.168.1.1/24 dev eth1
>    b) ip -4 rule add from all iif eth1 lookup 250
>    c) ip -4 route add local 0/0 dev lo proto kernel scope host table 250
>    d) arp -Ds 192.168.1.100 eth1
>    e) arp -Ds 192.168.1.200 eth1
>    f) sysctl -w net.ipv4.ip_nonlocal_bind=1
>    g) sysctl -w net.ipv4.conf.all.accept_local=1
>    # Assuming that the machine has 8 cores
>    h) taskset 000f netserver -L 192.168.1.200
>    i) taskset 00f0 netperf -t TCP_CRR -L 192.168.1.100 -H 192.168.1.200 -l 30
> 
> Signed-off-by: Mahesh Bandewar <maheshb@google.com>
[...]
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.