Forbes Mercy wrote: > Wow very interesting hypothesis since it happened right after a > lightning storm with heavy rain. Trouble is I shut off all six > backhauls and started turning them on one by one until I had a "IP > conflict" warning then turned that one off, the IP conflict happened > again, yes I did arp -d to clear the bouncing out of it but then it > happened on a different tower, I just can't seem to find it and yes > we're way too large to be bridged, that was our summer project to become > routed but that doesn't help today. It's a great idea but I have 54 > AP's so I don't know where to start. > > Forbes
Hi Forbes, I agree with Kurt (below), sounds like a layer2 issue. I had similar issues in the past, after storms. Typically a dumb switch on the network goes "bad", and causing arp problems. Now ... the hard part... how to find which device is causing the problem? Some ideas: 1) Try pinging a device on your network that you know is working fine. If you can't reach it, then good! Now immediately dump your arp table and look for the mac address of the ip you are trying to ping. This mac might be the "bad" device. Or at least it might point in the right direction (if you're doing proxy-arp on some of your links then the "bad" device may be located on the other side of this mac). 2) Start up wireshark (or tcpdump) and watch the arp packets. Look for a mac address which show up a lot. Dump your arp table and see what ip addresses match this mac address. Look for arp table entries which have the same mac, which is not normal (unless you're doing proxy-arp). Doing this may give some clues. If you have many different types of devices on your network, use one of the mac lookup tools to find out what kind of device it is, given the mac address: http://www.coffer.com/mac_find This might help narrow down the device. 3) Watch the stats on the radios to see which clients or radio links have high packet counts. If there is an arp storm, this may help you narrow down which client is causing the storm. (ideally do it at a time when your network is normally quiet, like early morning) 4) Focus on sites where you have dumb switches installed. I find these dumb switches often go berserk when zapped. 5) Focus on sites that have had problems in past storms. Chances are higher that they are causing your current problem. (in my case these sites are the ones which don't have shielded cat5 or are poorly grounded) 6) If your network covers a large geographical area and the storm was localized then focus on looking for the bad device in the area where the storm hit hard. Good luck. John > > On 8/1/2010 11:09 AM, Kurt Fankhauser wrote: >> Forbes, >> >> I remember seeing something similar to this on the list a few months back. >> Turned out he guy was running a bridged network and water got into the >> Ethernet connector on a Bullet and was causing Layer2 broadcast storms on >> the network. Very similar results to what you are reporting. >> >> Kurt Fankhauser -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
