PSINet/Cogent Latency

Tue Jul 23 05:50:03 UTC 2002

----- Original Message -----
From: "Phil Rosenthal" <pr at isprime.com>
Subject: RE: PSINet/Cogent Latency

> Call me crazy -- but what's wrong with setting up RRDtool with a
> heartbeat time of 30 seconds, and putting in cron:
> * * * * * rrdscript.sh ; sleep 30s ; rrdscript.sh
>
> Wouldn't work just as well?
>
> I haven't tried it -- so perhaps this is too taxing (probably you would
> only run this on a few interfaces anyway)...

Redback's implementation overcame the limitation of monitoring say, 20,000
user circuits. You don't want to poll 20,000 interfaces for maybe 4 counters
each, every 5 minutes.

I think the problem with using rrdtool for billing purposes as described is
that data can (and does) get lost. If your poller is a few cycles late, the
burstable bandwidth measured goes up when the poller catches up to the
interface counters. More bursting is bad for %ile (or good if you're selling
it), and the customer won't like the fact that they're getting charged for
artifically high measurements.

Bulkstats lets the measurement happen independant of the reporting.

--Doug