Source MAC addresses when bridge(4) used
Sten Daniel Sørsdal
lists at wm-access.no
Mon Jan 8 00:20:20 UTC 2007
Peter Jeremy wrote:
> I've just noticed an number of unpexected "IP address changed MAC"
> messages on one of the hosts in my network. It is connected via a
> FreeBSD bridge to the rest of my network (there aren't enuf network
> ports in my son's bedroom). The configuration looks like:
>
> +---------+ +---------+
> | | | |
> | laptop1 |---------| desktop |------> Rest of network
> | |dc0 tl0| |rl0 via dumb switch
> +---------+ +---------+
>
> The desktop network configuration is:
> tl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
> ether 00:00:24:28:98:9a
> media: Ethernet autoselect (100baseTX <full-duplex>)
> status: active
> rl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
> options=8<VLAN_MTU>
> inet 192.168.123.36 netmask 0xffffff00 broadcast 192.168.123.255
> ether 00:20:ed:78:9c:a3
> media: Ethernet autoselect (100baseTX <full-duplex>)
> status: active
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> inet 127.0.0.1 netmask 0xff000000
> bridge0: flags=8043<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
> ether ca:a9:aa:1e:71:32
> priority 32768 hellotime 2 fwddelay 15 maxage 20
> member: tl0 flags=3<LEARNING,DISCOVER>
> member: rl0 flags=3<LEARNING,DISCOVER>
>
> laptop1 is regularly reporting that 192.168.123.36 (the IP address of
> the desktop) is switching between the two adapters in it:
> Jan 6 07:27:09 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 08:09:45 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 08:46:11 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 09:29:00 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 12:12:12 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 12:15:31 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 13:06:42 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 16:48:45 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 17:32:22 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 17:33:33 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 17:53:45 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 17:57:05 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 18:17:20 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 18:24:48 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 18:45:08 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 18:48:19 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 19:08:45 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 19:11:50 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 19:32:15 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 19:33:07 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 19:56:34 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 6 22:44:24 laptop1 kernel: arp: 192.168.123.36 moved from 00:20:ed:78:9c:a3 to 00:00:24:28:98:9a on dc0
> Jan 6 23:04:26 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
>
> Even more unexpectedly, laptop1 is repeating the same "moved" message:
> Jan 7 00:46:55 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 01:38:09 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 02:29:26 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 03:20:39 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 04:28:59 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 05:18:50 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 06:28:31 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
> Jan 7 07:16:05 laptop1 kernel: arp: 192.168.123.36 moved from 00:00:24:28:98:9a to 00:20:ed:78:9c:a3 on dc0
>
> Both hosts are running 6.1-STABLE:
> laptop1: FreeBSD laptop1.vk2pj.dyndns.org 6.1-STABLE FreeBSD 6.1-STABLE #0: Wed Nov 15 18:40:00 EST 2006 root at laptop1.vk2pj.dyndns.org:/usr/obj/usr/src/sys/laptop i386
> desktop: FreeBSD jashank.vk2pj.dyndns.org 6.1-STABLE FreeBSD 6.1-STABLE #15: Wed Aug 2 18:35:57 EST 2006 root at jashank.vk2pj.dyndns.org:/usr/obj/usr/src/sys/jashank i386
>
> I'm not seeing similar messages on other hosts in my network, it seems
> that the desktop is always sending traffic to the rest of my network
> via rl0. This leaves two questions:
>
> Firstly, why is laptop1 seeing packets coming from both interfaces on
> the desktop? I had expected that the desktop would always originate
> packets from the interface with the IP address ("netstat -r" on it
> shows laptop1 associated with rl0).
>
> Secondly, why is laptop1 reporting a list of "address moved" messages
> from tl0 to rl0 without matching movements from rl0 to tl0?
>
Does moving 192.168.123.36 to the bridge interface help?
--
Sten Daniel Sørsdal
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