From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: If bridge have no sub-interfaces, it's status may be still with
 'RUNNING'
Date: Fri, 13 Feb 2015 13:30:56 -0500
Message-ID: <20150213133056.3944c13e@uryu.home.lan>
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Cc: netdev <netdev@vger.kernel.org>,
	"Wu, Kuaikuai" <Kuaikuai.Wu@windriver.com>,
	"Tao, Yue" <Yue.Tao@windriver.com>
To: yzhu1 <Yanjun.Zhu@windriver.com>
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On Fri, 13 Feb 2015 17:57:45 +0800
yzhu1 <Yanjun.Zhu@windriver.com> wrote:

> Hi, all
> 
> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
> 
> 1. brctl addbr br0
> 
> 2. ifconfig br0 up
> 
> 3. ifconfig br0 (br0's status is with 'RUNNING')
> 
> 4. brctl addif br0 eth0
> 
> 5. brctl delif br0 eth0
> 
> 6. ifconfig br0 (br0's status is without 'RUNNING')
> 
> When there is no sub-interface, the flag "RUNNING" is missing after the 
> last sub-interface is removed.
> 
> As such, should we keep "RUNNING" flag after the last sub-interface is 
> removed?

This is intentional. If there are no active ports in bridge, then
we want to tell applications that packets will go nowhere.