Bridge suddenly only passes traffic if in promiscuous mode
Hello,
I have a bridge to various interfaces. There is an IP address on the bridge, and hosts on the interfaces connected to the bridge use the bridge's IP address as a gateway. STP is off and the forwarding delay is set to 0.
This has been working fine, however, today I needed to change around some IPv6 addresses on the connected hosts. I made the IPv6 changes and rebooted those boxes, only to find that suddenly no traffic -- IPv4 *or* IPv6 -- was passing through the bridge.
When I pulled up tshark to see what was going on, traffic suddenly started flowing again. And even as I type this, as long as tshark is running on that interface (no matter what the capture filter is), traffic is flowing. The moment I stop tshark from running, traffic stops. IOW, the bridge is only passing traffic while in promiscuous mode.
I didn't change the IP address on the bridge itself. As far as I can tell I didn't do anything odd whatsoever. But I have no idea what's causing this and I'd really like to not reboot the box if at all possible.
Does anyone have any idea what might be causing this and/or how to troubleshoot this?
Thanks,
Jeff
Quoted 18 lines · Jeff Mitchell
Hello,
I have a bridge to various interfaces. There is an IP address on the bridge, and hosts on the interfaces connected to the bridge use the bridge's IP address as a gateway. STP is off and the forwarding delay is set to 0.
This has been working fine, however, today I needed to change around some IPv6 addresses on the connected hosts. I made the IPv6 changes and rebooted those boxes, only to find that suddenly no traffic -- IPv4 *or* IPv6 -- was passing through the bridge.
When I pulled up tshark to see what was going on, traffic suddenly started flowing again. And even as I type this, as long as tshark is running on that interface (no matter what the capture filter is), traffic is flowing. The moment I stop tshark from running, traffic stops. IOW, the bridge is only passing traffic while in promiscuous mode.
Quoted 6 lines
I didn't change the IP address on the bridge itself. As far as I can tell I didn't do anything odd whatsoever. But I have no idea what's causing this and I'd really like to not reboot the box if at all possible.
Does anyone have any idea what might be causing this and/or how to troubleshoot this?
What kernel version?
And, you are sniffing the physical interface, or the bridge?
Maybe send us output of brctl show, and ifconfig -a?
Promisc bit is sometimes hard to detect properly, so if you can, please post /sys/class/net/[iface-name]/flags
If bit 0x100 is set, the NIC is actually promisc, regardless of what ifconfig -a shows.
Thanks,
Ben
Quoted 7 lines
Thanks,
Jeff
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Signature · 2 lines
Ben Greear <[email protected]> Candela Technologies Inc http://www.candelatech.com
Quoted 28 lines · Ben Greear
Quoted 18 lines · Jeff Mitchell
Hello,
I have a bridge to various interfaces. There is an IP address on the bridge, and hosts on the interfaces connected to the bridge use the bridge's IP address as a gateway. STP is off and the forwarding delay is set to 0.
This has been working fine, however, today I needed to change around some IPv6 addresses on the connected hosts. I made the IPv6 changes and rebooted those boxes, only to find that suddenly no traffic -- IPv4 *or* IPv6 -- was passing through the bridge.
When I pulled up tshark to see what was going on, traffic suddenly started flowing again. And even as I type this, as long as tshark is running on that interface (no matter what the capture filter is), traffic is flowing. The moment I stop tshark from running, traffic stops. IOW, the bridge is only passing traffic while in promiscuous mode.
Quoted 6 lines
I didn't change the IP address on the bridge itself. As far as I can tell I didn't do anything odd whatsoever. But I have no idea what's causing this and I'd really like to not reboot the box if at all possible.
Does anyone have any idea what might be causing this and/or how to troubleshoot this?
What kernel version?
Quoted 8 lines
And, you are sniffing the physical interface, or the bridge?
Maybe send us output of brctl show, and ifconfig -a?
Promisc bit is sometimes hard to detect properly, so if you can, please post /sys/class/net/[iface-name]/flags
If bit0x100is set, the NIC is actually promisc, regardless of what ifconfig -a shows.
I found other funky behavior (sendmsg denied when trying to ping via IPv6) and users had trouble accessing services on the box, so I already initiated a reboot of the box -- I need those services up. :-|
If it happens again I'll be sure to get you that info.
However, here's what I *can* provide:
2.6.36 kernel, and sniffing the bridge. (There's actually no physical interface on the bridge -- this is on purpose, to prevent any problems on the bridge from affecting the one physical interface on the box, and thus my ability to get in and fix things.)
--Jeff