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I have two interfaces em1 and em2. I use the following config:

ifconfig_lagg0="laggproto failover laggport em1 laggport em2 192.168.1.99 netmask
255.255.255.0"

lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 08:00:27:78:54:9e
        inet 192.168.1.99 netmask 0xffffff00 broadcast 192.168.1.255
        media: Ethernet autoselect
        status: active
        laggproto failover
        laggport: em2 flags=0<>
        laggport: em1 flags=5<MASTER,ACTIVE>

When I ping 192.168.1.1 everything goes fine. I move to another console and take down the em1 interface

ifconfig em1 down
ifconfig lagg0
...same...
        laggport: em2 flags=4<ACTIVE>
        laggport: em1 flags=1<MASTER>

Ping 192.168.1.1 doesn't work anymore. I waited for some 5 minutes and it wouldn't budge. Then I brought em1 up. Hello sunshine ! It was working. Brought it down again - stopped working. What's more, I brought em0 up with some ip and it STILL wouldn't ping 192.168.1.1.

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 08:00:27:37:ca:72
        inet 192.168.1.121 netmask 0xffffff00 broadcast 192.168.1.255
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active

So I start thinking freebsd gave up on me with a I-wont-ping-your-stupid-ip attitude. On 192.168.1.1 tcpdump shows it's pinging it (packets coming from 192.168.1.99). Back on freebsd it shows the same (it actually shows outgoing packets - from 192.168.1.99 - and orderly replies). But ping doesn't show ANYTHING, 100% packet loss wohooo. So I decide to really look into tcpdump.

I see icmp requests originating from 08:00:27:78:54:9e to the mac on 192.168.1.1. And I see icmp replies originating on 192.168.1.1 to the mac 08:00:27:78:54:9e. Then I see it's the MAC of em1 and lagg0.

So, although I took the interface down, it still sends packets with the same source mac. (And so it doesn't work in a very creative way. I can ping from 192.168.1.1 but not the other way around.

Mind you, the same happens when instead of taking down the interface I unplug the cable. This way I can't see how failover works. How can I solve this problem ? Any help is appreciated.

share|improve this question
    
So you have 3 addresses from one subnet on all three interfaces? –  SaveTheRbtz Aug 10 '10 at 8:16
    
Initially there was some other address on em0. I then added it for testing. Also, I don't think they should be considered "three interfaces". After all, the only interfaces that have ip addresses are lagg0 and em0. –  nc3b Aug 12 '10 at 7:53
    
Where the heck did 192.168.1.1 come from? I see absolutely no explanation of where it is at all. If it's on the same machine, then these pings will never leave the machine; but tcpdump wouldn't show anything for interface em0, em1, or lagg0. In any case, the question doesn't make sense. –  Chris S Aug 6 '11 at 2:35
    
@Chris S It's a different (non-BSD) machine. See the paragraph "When I ping 192.168.1.1 everything goes fine". –  nc3b Aug 6 '11 at 9:49
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