[c-nsp] QoS on ingress

[Keegan Holley]

On Sat, Sep 11, 2010 at 9:52 AM, Heath Jones <hj1980 at gmail.com> wrote:

> The priority traffic will never be prioritised on the carrier egress, with
> or without this method. What this is trying to achieve is reducing the
> amount of inbound tcp traffic from the congested link.
>
> Your logic is right so far, but follow it forward in time a bit (thats what
> people arent doing). People are getting stuck at step 1.
> 1) Apply a policy for egress on the lan side, to give the voip priority
> over
> tcp traffic (reduce tcp throughput). Like you said, this wont have any
> effect - YET.
> 2) Clients on the LAN will not see the tcp traffic immediately, clients
> will
> therefore not be sending acknowledgements back to the remote end of the tcp
> connection.
> 3) The sending side will slow down the rate of transmission because it is
> not seeing acknowledgements coming back in as fast as it is sending
> segments
> out. This is commonly referred to as 'backing off'.
>

I agree that TCP will back off if policed however if he only has 1M to work
with he might be stuck.  I've filled up a 1M pipe with an iPhone...  If
there are enough TCP sessions the congestion will still happen.


> H
>
>
>
> On 11 September 2010 14:29, danger will <myniuid at yahoo.com> wrote:
>
> >   I totally agree with Keegan queuing has to be done where the congestion
> > actually occurs.
> > Even if you would queue on the lan interface on output , because you
> can't
> > queue on the wan interface on input that doesn't  have much effect
> because
> > the congestion has already occured a few hops away from you. I did some
> > tests like this and the priority traffic didn't seem to get prioritized
> at
> > least this is the conclusion i came up with.
> > The links were mpls links and i was trying to prioritize voip traffic
> from
> > another site. Do you guys have positive experiences with this method ?
> >
> >
> >
> > --- On *Sat, 9/11/10, Brian Landers <brian at bluecoat93.org>* wrote:
> >
> >
> > From: Brian Landers <brian at bluecoat93.org>
> > Subject: Re: [c-nsp] QoS on ingress
> > To: "Heath Jones" <hj1980 at gmail.com>
> > Cc: "cisco-nsp" <cisco-nsp at puck.nether.net>
> > Date: Saturday, September 11, 2010, 5:25 AM
> >
> >   There was actually a very interesting session at Cisco Live 2010 on
> > inbound QoS for branch offices, using an outbound shaper on the inside
> > interface of the router (e.g. on the gigE interface going to your
> > switches).  I don't recall the specifics, but the presenter had quite
> > a bit of concrete data around the effects on latency, jitter, and
> > p.loss.
> >
> > B*
> >
> >
> > --
> > Brian C Landers
> > http://www.packetslave.com/
> > CCIE #23115 (R&S + Security)
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> >
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