Source MAC addresses when bridge(4) used
Peter Jeremy
peterjeremy at optushome.com.au
Sat Jan 6 21:02:13 UTC 2007
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?
--
Peter Jeremy
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