We have seen this as well. We reported it to our carrier, since crc's
typically indicate line trouble. They called in the telco, who fumbled
with it for three weeks. They eventually made some line adjustments
(said the signal was too hot), and we went from outages like you
describe happening every few hours to outages happening once every
several days now. They usually are accompanied by a small number of
crc's like you describe. The telco's test equipment never reports any
errors, of course. I suppose that if I paid for my CSU/DSU what they
paid for their test equipment, my CSU/DSU would likely never have
trouble either. :-)
The telco swears there is nothing wrong with the line now, and the
carrier swears we should never get even one crc, since we are on fiber.
So who's not coming clean? I have replaced both the CSU/DSU and the
router twice now, so I do not believe it is broken hardware. We have a
new multi-port CSU/DSU coming in in a week or so, and then we will have
the opportunity to see if the errors go away, in which case it means
our Black Box CSU/DSU was at fault (compat/config/whatever).
FWIW, we ran without this kind of trouble too, for months. It began
September 4, when they upgraded our backbone from 128K to 256K. We will
be going to 512K in the next few weeks, so it should be interesting to
see what if anything happens to the problem then.
In our case, we almost never reset the port, because it recovers on its
own in a couple of minutes. Typically by the time we recognize the
freeze, confirm it and try to reset, it has come recovered. Like you say,
annoying but not a huge issue.
> Any one else seen this? BTW there are no alarms or errors on my CSU/DSU
> (ADTRAN TSU).
When these problems occur, the Cisco 7000 at the carrier's end of our
connection reports crc's as well; our CSU/DSU doesn't have any
intelligence to be reporting anything to anyone. :-(
> Do I need to upgrade ComOS (currently 3.1.2)? Not just a blanket upgrade
> statment, please.
Now that you mention it, that is one common factor on every hardware
combo we have tried. Our 3.1.2 PM2ER-30 otherwise appears to be solid,
and since horror stories can be heard about any release, we aren't
going to upgrade ours unless we hear something specific about a fix to
this particular problem in a new release. We won't upgrade without
specific reason, since every change carries an element of risk.
I would be interested in any informed feedback on this problem as well.
Thx,
dennis