Yes, that's why on my other switches (Procurve 2510-48), I have set up loop-detect parameters, in addition to spanning tree. I have it lock out the port for 10 minutes.
Kurt On Fri, Sep 20, 2013 at 10:53 AM, Reimer, Mark <[email protected]> wrote: > I've seen a wire with both ends plugged into a little 5/8 port switch that > caused the problem. But it was a long down time, until I found the wire. > > Mark > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Kurt Buff > Sent: Friday, September 20, 2013 10:59 AM > To: [email protected] > Subject: [NTSysADM] Semi-OT: Network problem > > All, > > In the past couple of weeks, $work has had a problem with network > interruptions - frequent gaps in network connectivity were all contact is > lost with servers for brief periods of time (1-2 minutes, usually). > > I could see the gaps in the graphs on my (very new and incomplete - long > story, don't ask) cacti installation. Unfortunately, I've been unable to get > cacti to graph CPU utilization for the switches, because they're Procurves, > and I couldn't find a working XML file or configuration for that. > > It's always happened while I've been unavailable, until today. > > Just now, I was able to show conclusively that our core layer3 switch > (Procurve 3400cl-48G), which was hit hardest, spikes its CPU to 99% during > these episodes. Volume of traffic is normal - ho huge spikes in that, just > normal variation, AFAICT, from the cacti graphs. I haven't had time to see if > other switches also spike their CPU, but given the gaps in the graphs, I > suspect that's the case. > > I suspect someone is doing something stupid to create layer2 loop, as we have > lots of little 5 and 8 port switches on desktops and in our engineering lab - > and in spite of the fact that I've set our core switch as the root of the > spanning tree. > > I'm setting up a box to do a tcpdump in a ring buffer with smallish files so > that I can do analysis on them more easily. > > I'm not a packet analysis guy, though I've done some looking on occasion. > > Anyone have thoughts on what to look for when I start my analysis? > > Kurt > >
