From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH v2] net: Allow ethtool to set interface in loopback mode. Date: Tue, 4 Jan 2011 16:36:45 -0800 Message-ID: <20110104163645.0b3a3687@nehalam> References: <1294187401-4662-1-git-send-email-maheshb@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , Ben Hutchings , Laurent Chavey , Tom Herbert , netdev To: Mahesh Bandewar Return-path: Received: from mail.vyatta.com ([76.74.103.46]:43715 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751641Ab1AEAgr (ORCPT ); Tue, 4 Jan 2011 19:36:47 -0500 In-Reply-To: <1294187401-4662-1-git-send-email-maheshb@google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 4 Jan 2011 16:30:01 -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 > Reviewed-by: Ben Hutchings Since this is a boolean it SHOULD go into ethtool_flags rather than being a high level operation. --