Date: Thu, 18 Feb 2010 12:02:55 -0500 From: Boris Kochergin <spawk@acm.poly.edu> To: freebsd-net@freebsd.org Subject: CARP vs. if_bridge Message-ID: <4B7D72BF.1040104@acm.poly.edu>
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Ahoy. I'm seeing what appears to be erroneous interaction between CARP
and if_bridge on multiple machines with a variety of Ethernet
controllers and architectures. I've observed it on 7.2-R and 8.0-R. The
test setup is simple enough:
CARP master:
FreeBSD t30 8.0-RELEASE-p1 FreeBSD 8.0-RELEASE-p1 #5: Sun Feb 14
20:22:41 EST 2010 root@t30:/usr/obj/usr/src/sys/T30 i386
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
dc0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
mtu 1500
options=8<VLAN_MTU>
ether 00:04:5a:a8:e0:bf
inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
inet 192.168.0.1 netmask 0xffffff00
carp: MASTER vhid 1 advbase 1 advskew 0
CARP backup:
FreeBSD ultra5 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Thu Feb 18 15:19:39
UTC 2010 boris@ultra5:/usr/obj/usr/src/sys/GENERIC.carp sparc64
hme0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
ether 08:00:20:f5:65:d4
media: Ethernet autoselect
xl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
mtu 1500
options=9<RXCSUM,VLAN_MTU>
ether 00:01:03:2c:06:6d
inet 192.168.0.3 netmask 0xffffff00 broadcast 192.168.0.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
inet 192.168.0.1 netmask 0xffffff00
carp: MASTER vhid 1 advbase 1 advskew 100
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu
1500
ether 3a:e6:09:2d:da:bc
id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
member: xl0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
ifmaxaddr 0 port 2 priority 128 path cost 200000
member: hme0 flags=8<SPAN>
ifmaxaddr 0 port 1 priority 128 path cost 200000
In summary, I have a basic CARP configuration and, on the backup CARP
machine, a bridge with the CARP device's physical interface in it. The
purpose of this setup is the ability to monitor traffic passing through
that interface using another machine. If the master CARP machine is
disconnected from the network, the CARP interface on the backup machine
correctly changes to the MASTER state, but does not act on traffic bound
for the shared IP address--192.168.0.1. tcpdump shows the traffic coming
in on the correct physical interface, but it is never replied to, or, in
the case of routing, forwarded. Removing xl0 from the bridge on the
backup machine instantly fixes this, and the shared IP address behaves
as expected. Adding xl0 back to the bridge while the backup CARP
interface is in the MASTER state keeps things running correctly, so the
problem is only observed when xl0 is part of the bridge during the CARP
transition from BACKUP to MASTER. Thoughts?
-Boris
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