Re: forwarding didn't work if wlan0 is member of a bridge

After weeks of troubleshooting, at last I found how to reproduce this
problem ;-)

Here is the setup:

LAN0 <--> [(re0) fbsd router (bridge0 addm re1 addm wlan0)] <--> Wireless
LAN

If interface re1 (bridge0 member with wlan0) is in "active" status
(=ethernet cable plugged to something): I don't have any problem, all is
working great for my wireless clients connected to wlan0: They can ping
devices in LAN0.
But once I've unplug the ethernet cable connected to re1 (bridge member
with wlan0) and re1 state switch to "no carrier", Wireless LAN clients are
not able to reach LAN0.

Here is my rc.conf with simple subnetting for Adrian ;-)

wlans_ath0="wlan0"
ifconfig_wlan0="hostap channel 6"
create_args_wlan0="wlanmode hostap"
cloned_interfaces="bridge0"
ifconfig_re0="inet 1.0.0.1/24"
ifconfig_re1="up"
ifconfig_bridge0="inet 1.1.1.1/24 addm re1 addm wlan0 up"
gateway_enable="YES"

And an example with re1 in "no carrier" status:

root_at_fbsd-router:~ # ifconfig bridge0
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu
1500
        ether 02:6b:c0:de:b8:00
        inet 1.1.1.1 netmask 0xffffff00 broadcast 1.1.1.255
        nd6 options=9<PERFORMNUD,IFDISABLED>
        groups: bridge
        id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
        maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
        root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
        member: wlan0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 5 priority 128 path cost 33333
        member: re1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 2 priority 128 path cost 55


root_at_fbsd-router:~ # ifconfig re1
re1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
mtu 1500

options=82099<RXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
        ether 00:0d:b9:3c:ae:25
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (none)
        status: no carrier

=> from a wireless LAN client (1.1.1.2) I'm trying to ping a host on LAN0
(1.0.0.2):

root_at_fbsd-router:~ # tcpdump -pni re0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on re0, link-type EN10MB (Ethernet), capture size 262144 bytes
23:38:04.466866 ARP, Request who-has 1.0.0.2 tell 1.0.0.1, length 28
23:38:04.467052 ARP, Reply 1.0.0.2 is-at 00:08:a2:09:c4:a2, length 46
23:38:04.467090 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 1,
length 64
23:38:04.467226 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 1, length
64
23:38:04.467300 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
36
23:38:05.483053 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 2,
length 64
23:38:05.483259 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 2, length
64
23:38:05.483318 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
36
23:38:06.387304 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 3,
length 64
23:38:06.387466 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 3, length
64
23:38:06.387514 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
36
^C
11 packets captured
11 packets received by filter
0 packets dropped by kernel
root_at_fbsd-router:~ # arp -na
? (1.1.1.1) at 02:6b:c0:de:b8:00 on bridge0 permanent [bridge]
? (1.1.1.2) at fc:64:ba:97:c0:ff on bridge0 expires in 1168 seconds [bridge]
? (1.0.0.1) at 00:0d:b9:3c:ae:24 on re0 permanent [ethernet]

=> The FreeBSD router answers "unreacheable" to the host: My wireless LAN
client never get the ICMP reply.

=> Now I plug eth1 to a dummy machine (just for changing its status):

root_at_fbsd-router:~ # ifconfig re1
re1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
mtu 1500

options=82099<RXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
        ether 00:0d:b9:3c:ae:25
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active

=> and I restart the same ping from the wireless LAN client:

root_at_fbsd-router:~ # tcpdump -pni re0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on re0, link-type EN10MB (Ethernet), capture size 262144 bytes
23:44:08.597429 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 1,
length 64
23:44:08.597660 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 1, length
64
23:44:09.604447 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 2,
length 64
23:44:09.604683 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 2, length
64
23:44:10.609711 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 3,
length 64
23:44:10.609874 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 3, length
64

=> It's works :-)

How the status of a member of the bridge can impact the routing behavior of
other interfaces ?
How to fix this problem ?

Thanks