[j-nsp] QoS when there is no congestion

[Andrey Khomyakov]

I think this is where I was misunderstood. Firstly, "proper" user
*shouldn't* (see points about policers) hurt, but "proper" requires
research into your whole network. The point I was making was based on the
OP's initial statement that there is no congestion in the network, QoS will
not help anything, because as long as the packet is not being buffered
(queued), it won't have a chance to be reordered by QoS, but rather will go
straight to the tx ring.

Again, I can't state this enough: the OP explicitly stated lack of
congestion *anywhere in the network*. The rest are assumptions made that OP
simply doesn't realize that there is congestion on the network.

So put it simply, if there is no congestion *anywhere* QoS is a lot of
effort with very little to no payback and new risks coming from potential
for  improper configuration and additional complexity.
If there is congestion, then by all means, make the business case that
additional complexity and configuration management costs are lower than
simply increasing the size of the pipe where congestion is. Hence YMMV note.
At the end it all comes down to $$$. If you can demonstrate that tinkering
with QoS is cheaper than not, I agree, go with QoS.


--Andrey

On Tue, Nov 15, 2016 at 2:44 AM, <adamv0025 at netconsultings.com> wrote:

> > Of Andrey Khomyakov
> > Sent: Monday, November 14, 2016 4:56 PM
> >
> > OP explicitly stated that there is not congestion. I think we can all
> agree that
> > QoS only works if there is congestion on the egress line. In cases where
> > egress rate is lower than line rate, QoS will simply hurt more than help
> since
> > you'll be potentially limiting any given class with police or shape (I
> know this is
> > juniper list, but I don't know junos equivalents) statements to below
> the line
> > rate.
> >
> Hey buddy,
> First of all I suggest you get some reading on QOS to get the basics
> right, how on earth can proper use of policing and shaping hurt?
>
> My experience is that OP is probably unaware of all the congestion points
> (including congestion points within devices themselves) because 99% of
> folks I talk to are not, unfortunately.
> No, I don't agree that QOS works only if there is congestion on an egress
> line, see above.
>
>
> adam
>
>
> netconsultings.com
> ::carrier-class solutions for the telecommunications industry::
>
>
>