Severe bridge issues. [SOLVED - bad switch]

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

Everything has been working fine for upwards of 6 months. Currently for wireless I am using an Atheros card with Madwifi. My network setup looks like this:

br0 (eth0, ath0), eth0 goes to switch/rest of LAN
eth1: internet

br0 has my internal IP address (192.168.0.1), I also run DHCP internally

About an hour ago, the wired computers suddenly lost all network access. DHCP fails to renew, and even the Linux boxes are getting some kind of bogus 169.254 IP address (which should only happen with Windows clients that fail to renew). If I set their IP's manually they can talk to the server, but DHCP fails. DHCP is still working normally on the wireless clients. dhcpd is set to serve on br0, so it shouldn't matter if wired/wireless, and in fact has been working for 6 months. From what I can see of the configuration, it should all work, there is no technical reason why it should not (server logs indicate that bridge is forwarding normally and should be working). I see it as a technical impossibility at this point, but there is obviously something wrong. As an absolute last resort, I rebooted the server (which I NEVER EVER do except to change the kernel), and still nothing. I'm completely lost, any assistance would be appreciated.

Paczesiowa · Posted: Sat Nov 17, 2007 6:09 pm Post subject:

do you use authoritative mode in dhcp software?

if it's not that, maybe some package update broke it? I can give you later my versions of software (I have the same setup)

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

I do use authoritative mode for DHCP, but DHCP itself isn't the problem. Even if I set the IP address manually, it still doesn't work. I have to start a ping to the server, then do another ping back from the server to the wired machine, then that one will communicate. Internet access works at that point, but I still cannot ping across the bridge (no communication with wireless systems even though they can see the server/internet also), and DHCP still fails. This is something in the kernel bridging itself that has to be wrong, but I haven't changed the kernel for quite some time.

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

I've confirmed that it is not a hardware issue. If I take the bridge out of the equation (put the IP on eth0) and run dhcpd on eth0, everything works as it did before. Of course, that does mean losing my wireless network. Previously, I had the IP address on br0, and had eth0 and ath0 set to null, and ran dhcpd on br0, that worked perfectly fine for a year, and suddenly stopped this morning when I had made no changes.

Paczesiowa · Posted: Sun Nov 18, 2007 3:01 am Post subject:

what is your

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

Paczesiowa · Posted: Sun Nov 18, 2007 6:46 am Post subject:

are you sure you have

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

I don't have that...but right now it's working and I still don't have that. I try not to use interfaces in iptables rules as a general rule, so my forwarding rules just refer to 192.168.0.0/24 instead of the interface.

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

Akaihiryuu · l33t Joined: 08 May 2003 Posts: 794 Location: Columbus, OH

Well, after lots of intermittent working and lots of pulling my hair out (especially since nothing changed between the working/not working states)...I finally found the source of the problem: my switch. Apparently it was dying and not consistently passing traffic. It stopped working entirely no matter what I did...and then I noticed that the light for one of the ports stayed on even if all ethernet cables were unplugged from it. Power cycle and it came back the same way. Replaced the switch and everything is fine again. So it was never a problem with the bridging setup at all, it was a flakey switch the entire time!