My first guess would be that maybe the switches had been configured to turn VLANs on some time in the past, their configs saved to firmware, then the VLAN configurations were taken off but not saved. The power cycles then reverted the switches to that old saved state with the VLANs back on. Of course, that's just one avenue to check. Don't forget to rule out something causing a flood of the network, possibly broadcasts from a buggy box. Just don't make the mistake that a lot of people do and assume that it's some sort of attack without first checking out other possibilities and narrowing down the problem.
-Tim CMB wrote: > OK, I have one for you... > > Today, around 11:30 or so, my BAY 281XX switches and XLR1200 started > freaking out. No one could talk on network without dropping massive > packets. Novell Server was reporting that it had an ip conflict with > itself. > > Ethereal on Knoppix-STD reported no weird packets. EtherApe showed > healthy network activity. Cheops mapped out a partial network. > (Knoppix-STD really rocks, I brought it up on one of my dual CPU > machines and was impressed..) > > I shut down the net and took up back up slowly; the end of the net on > the other side of my backbone (LX) ports stabilized but my > 28XXX switches cycled cpu utilizations up and down ranging from 100% > to 50% (normal is 5%). It was nasty. I went through those and > isolated a connection on an expansion port. This sent utilizations > back to normal but I couldn't route between switches. > > Brought up some more and they put the network into chaos. I had to > power down three of my front office switches and leave up two that ran > vital services. > > All front office machines were offline. > > I went to verify the config on the nasties and noticed that all front > office 281XX switches had VLan enabled. (Even the ones that worked) > WTF? Huh? Fixed 'em and network started performing wonderfully. I > am still scratching my head as to how these got turned on and why the > setting mattered to the router....but I do have a theory as to what > caused them. > I'd like to know your ideas? > > Keep in mind, these are about 6 or 7 years old (were configured before > I got there), our main UPS feeding these is in bypass because its > fried itself (Thanks Toshiba), We've had a couple of unexpected power > offs, and the electricians were working on light-ballasts today. > > > > > > > > > _______________________________________________ > General mailing list > [email protected] > http://brlug.net/mailman/listinfo/general_brlug.net
