[c-nsp] Ethernet Freezeup

[Ed Ravin]

On Tue, Apr 08, 2008 at 08:36:57PM +0200, Andre Beck wrote:
> Hi Jon,
> 
> On Tue, Apr 08, 2008 at 10:35:36AM -0500, jon.hartman at verizon.com wrote:
> > Is it possible that your interface is getting wedged?
> > 
> > http://www.cisco.com/en/US/products/hw/iad/ps397/products_tech_note09186a0
> > 0800a7b85.shtml
> 
> Hard to say without having a "sh int fa0/0" from when the issue hit. The
> description says that only a reload would clear this kind of problem,
> but it's old and things may have changed. My Fa0/0 input queue looks like
> 
>   Input queue: 0/75/0/2 (size/max/drops/flushes); Total output drops: 0
> 
> and I ponder what the two flushes may be. I did indeed have exactly two
> occasions of the interface hanging that could be cleaned with a clear int.

Compare that with my 7200 :

  Input queue: 0/75/19755/291735 (size/max/drops/flushes); Total output drops: 715217
  ...
   Received 23535684 broadcasts, 0 runts, 233 giants, 4480 throttles
   568580 input errors, 0 CRC, 0 frame, 396581 overrun, 171629 ignored


That's after around 5 weeks of uptime.  We had a DoS attack a couple of
weeks ago, that might explain the crazy numbers.

BTW, it's not memory, neither of my two routers that have the problem
are memory constrained nor do they have a lot of routes.

> Further, just giving it a clear int when it is running normally doesn't
> increment that counter. When it strikes again (hopefully auto-healed by my
> new EEM applet) and that counter increments, it's probably indeed an input
> queue overrun (wedged).

Will the EEM applet leave something in your log when it resets the
interface?  Otherwise, if the auto-heal happens fast enough, you might
not know that it kicked in.

> BTW, there's also a chance of the switch being involved.

I've checked this a couple of times and never found anything.
Also, the two routers affected are in wildly disparate environments.