[rrd-users] Re: COUNTER to DERIVE

Jesper Skriver jesper at skriver.dk
Fri Dec 29 18:56:31 MET 2000

On Fri, Dec 29, 2000 at 11:45:21AM -0600, Dave Plonka wrote:
> On Fri, Dec 29, 2000 at 11:36:28AM -0500, David Koski wrote:
> > 
> > Dave,
> > 
> > 	Just to clarify...  I'm moving from COUNTER to DERVIE with rrd-min
> > set to 0 to remove any spikes that occur in the couter wrap code due to
> > huge counter wraps, router reloads, etc.  Since RRD tries to compensate
> > for the counter roll instead of just throwing out the data (AKA Concord
> > Network Health's way of dealing with a counter roll), I need some way to
> > just ignore any spike that could occur in the RRD counter wrap logic.
> Thanks for the clairification...
> I like that method of just discarding the value when the counter
> wraps.  In RRD terms that would mean recording the PDP Status info, but
> storing NaN (Tobi's *UNKNOWN*) in the RRA, which sound like what will
> happen if you switch to DERIVE with the DS' min set to zero.

The only problem is that for highspeed interfaces counter wraps can
occur quite often, like every few minutes (or even seconds for very
highspeed interfaces) ...

> Hmmm... I think we're getting mostly good values from our HC counters,
> but most of those are on ethernet switch ports rather than router
> interfaces, so its very different Cisco hardware and code than on your
> routers.  I'll keep your report in mind when we consider using the HC
> counters on our WiscNet routers.

I only have good experiences with using 64 bit counters on our GSR's
running 12.0(x)S and on our 7500's running 12.1(x)


Jesper Skriver, jesper(at)skriver(dot)dk  -  CCIE #5456
Work:    Network manager @ AS3292 (Tele Danmark DataNetworks)
Private: Geek            @ AS2109 (A much smaller network ;-)

One Unix to rule them all, One Resolver to find them,
One IP to bring them all and in the zone to bind them.

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