[c-nsp] Cisco ToS/CoS/DiffServe

[Lawrence Wong]

Thanks Ytti.

I'm a "service provider" serving the users in my
office network. ^^

I'm looking along the line of ensuring certain
"service level" for VoIP and ERP applications running
through the internal LAN in the face of sparodic burst
of traffic when other users copy files from the other
servers on the same network.

Would ToS/DiffServe be an overkill for this?

--- Saku Ytti <saku+cisco-nsp at ytti.fi> wrote:

> On (2006-03-31 23:38 -0800), Lawrence Wong wrote:
> 
> Hello,
> 
> > I read from the documentation that switches like
> the
> > 2960 and 3560 support QoS based on
> ToS/CoS/DiffServe,
> > etc.
> 
> prec5 (101) == dscp40 (101000) == tos160 (10100000)
> 
>  CoS is 3 bits also. prec,dscp,tos are all from IPv4
> 'tos byte' just giving remaining extra bits
> different
> meanings, so changing prec changes dscp and tos too.
>  CoS of course is in 802.1q headers only and can
> have
> different value to that off 'tos byte' content.
> 
> > Does anyone have any idea how the QoS settings can
> be
> > verified? Or how will I know whether the actual
> > traffic has indeed been given the CoS which I
> wanted
> > to set?
> 
> lab, lab, lab and lab testing if you're service
> provider.
> catalysts aren't the most trivial platform to get
> QoS
> right :/, using extensive lab testing will probably
> be
> only way to get it right.
> If you're 'user' of the QoS, then apparently you
> don't 
> need the QoS if you can't know if it works or if it 
> does not work (if you can't observe quality issues,
> why bother fiddling with QoS).
> 
> example from my own connection, typical DSL
> connection
> with large downstream, low upstrea. If my QoS were
> suddenly to break down. I could immediately observe
> it when I next time upload something, by my mp3
> playing (over samba), tv-series (over http),
> interactive
> ssh sessions (upstream latency) and download
> (upstream
> tcp acks) having severe quality issues. In my case
> QoS
> is simply prioritizing small packets (<200 bytes)
> upstream, which will take care of all of the
> problems
> that I can observe as a user. 
> 
> -- 
>   ++ytti
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