[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

-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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