[ntp:questions] Detecting bufferbloat via ntp?
Hal Murray
hal-usenet at ip-64-139-1-69.sjc.megapath.net
Wed Feb 9 00:30:25 UTC 2011
In article <87aai6d0t6.fsf at cruithne.co.teklibre.org>,
d at taht.net (Dave =?utf-8?Q?T=C3=A4ht?=) writes:
>
>I've been racking my brain trying to come up with a good way of
>semi-passively detecting bufferbloat at the datacenter.
>
>What would wild swings in latency on the order of seconds from a ntp
>client register on a ntp server as?
Are you trying to detect it in real time, or collect long term
data?
Turn on rawstats. (info in monopt.html) That will log 4 time
stamps for each ntp packet received. If the time on both systems
is accurate, that will give you a pair of one-way times.
ntp tries to filter out the packets with long (queueing) delays
so you will see the bad stuff in rawstats that you won't see
in peerstats or ntpq -peers
--
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