[ntp:questions] Detecting bufferbloat via ntp?

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Wed Feb 9 13:11:27 UTC 2011


David Woolley wrote:
> Hal Murray wrote:
>> In article <iithjg$83s$1 at news.eternal-september.org>,
>> David Woolley <david at ex.djwhome.demon.invalid> writes:
>>> Dave T=E4ht wrote:
>>
>>> A well managed router would prioritised NTP traffic and isolate it
>>> from=20
>>> the buffering, which should only really affect bulk TCP traffic.
>>
>> How many routers to that?

Effectively none? :-(
>
> I would imagine that most intranet backbone routers are capable of it,
> actually, I think many domestic ones are. I would suspect that very few
> are configured to do so, but that is based on a gut feeling as to the
> importance of NTP to IT managers in general.


All modern routers are capable of QoS, i.e. using packet tags and/or sw 
config rules to prioritize specific packets. The classic Cisco example 
is in their white paper about VoIP, where you can read that on 
realtively slow lines they will even intentially fragment regular 
(1500-byte ethernet) packets, splitting them into 3 500 byte packets in 
order to be able to guarantee that an incoming short packet with 
realtime priority will be able to go out quickly.

The crux of the matter is that close to nobody actually implements this, 
even if all involved carreres happens to support it.

Getting NTP into that realtime group across the entire Internet is a 
non-starter.

Terje
-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"




More information about the questions mailing list