Date: Sun, 17 Oct 2010 16:17:01 +0000 (UTC) From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: Nikolay Denev <ndenev@gmail.com> Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org, FreeBSD virtualization mailing list <freebsd-virtualization@freebsd.org> Subject: Re: ifconfig, vnets and interface names Message-ID: <20101017161256.U10185@maildrop.int.zabbadoz.net> In-Reply-To: <7051D018-684F-417A-AAA0-00603B2FDCD4@gmail.com> References: <7051D018-684F-417A-AAA0-00603B2FDCD4@gmail.com>
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On Sun, 17 Oct 2010, Nikolay Denev wrote: > Hello, > > While playing with vnet jails I've discovered the following oddity, which probably is not what's expected to happen : > ... > And that's what ifconfig shows after this : > > [16:52]root@nas:/home/ndenev# ifconfig > <... snip lo0 and physical interface ...> > epair0a: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > ether 02:8c:53:00:03:0a > epair1a: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > ether 02:b6:49:00:05:0a > eth0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > ether 02:8c:53:00:04:0b > ether 02:b6:49:00:06:0b > > Instead of two interfaces, I'm seeing one with to lladdrs, because of the interface names being the same. > > Then I'm trying to destroy them : > > [16:52]root@nas:/home/ndenev# ifconfig eth0 destroy > [16:53]root@nas:/home/ndenev# ifconfig > <... snip lo0 and physical interface ...> > epair1a: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > ether 02:b6:49:00:05:0a > eth0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > ether 02:b6:49:00:06:0b > [16:53]root@nas:/home/ndenev# ifconfig eth0 destroy > > > So in this case there may be not a clean way to address one of the interfaces specifically (i.e. destroy only the second one)? > > I've not investigated further, but I'm thinking probably this is just a "bug" in ifconfig interpreting/parsing the information from the kernel. > Maybe a solution is to extend ifconfig to be able print the interface list along with the ifIndex values and also manage the interfaces by index? > Auto renaming also is also probably a possible solution (i.e. eth0_1 , eth0_2 ) as these are interfaces coming from destroyed vnet's and are not likely to be in use. (but still sounds scary :) ) It's actually a bug in sys/net/if.c:if_vmove* we know about and that's on the todo list. I am not sure when the behaviour of ifconfig changed as previousy it would only show you one of the two interfaces with the single ether address. ifconfig -l however had shown eth0 twice. Neither is really what one would expect thus needs changing. /bz PS: freebsd-virtualization@ is the best list to report "VIMAGE" or "vnet" related problems. -- Bjoern A. Zeeb Welcome a new stage of life.
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