[c-nsp] VOIP QoS problem

[Fedorov, Konstantin]

Hi

Several thoughts

PQ in LLQ always police traffic which matched its class.
So , this is very easy overwhelm it. For exam: You use 65% 
from 75% of T1 bandwidth so - 748kbps
1 call g729 - 24 kbps
1 call g711 - 80 kbps

So if you put on this link a lot of calls , it is very easy to obtain
drops
On PQ, which lead to voice degradation + you put signaling packets also
to the PQ this is not very common, in general it is better put signaling
packets into its own queue with reserved bandwidth.

And check tx-ring on the interface. Because PQ - this is software queue
but interface also have FIFO, I couldn't find a link now on CCO. But
this is known tip.


-----------------------
Sincerely Yours,
Konstantin Fedorov

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Eric Kagan
Sent: Monday, August 28, 2006 4:58 AM
To: 'Brant I. Stevens'; sgranados at jeteye.com; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] VOIP QoS problem

> 
> What does the output of "show policy-map interface" provide?

>show policy-map interface
 Serial5/0/18:1

  Service-policy output: voice

    Class-map: VOIP (match-any)
      3907283 packets, 968793011 bytes
      5 minute offered rate 4000 bps, drop rate 0 bps
      Match: protocol rtp
        3381834 packets, 694582632 bytes
        5 minute rate 0 bps
      Match: protocol sip
        525449 packets, 274210379 bytes
        5 minute rate 4000 bps
      Queueing
        Strict Priority
        Output Queue: Conversation 264
        Bandwidth 65 (%)
        (pkts matched/bytes matched) 362279/86354233
        (total drops/bytes drops) 325/253673
      QoS Set
        ip precedence 5
          Packets marked 3907283

    Class-map: class-default (match-any)
      9540569 packets, 3881841498 bytes
      5 minute offered rate 8000 bps, drop rate 0 bps
      Match: any

> 
> 
> On 8/27/06 4:44 PM, "Scott Granados" <sgranados at jeteye.com> wrote:
> 
> > This may be totally unimportant, but shouldn't the 
> bandwidth setting 
> > be 1536?  ESF, B8zs with 8K framing?
> > 
> > 
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net 
> > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Eric Kagan
> > Sent: Sunday, August 27, 2006 1:35 PM
> > To: cisco-nsp at puck.nether.net
> > Subject: [c-nsp] VOIP QoS problem
> > 
> > We have several customers that utilize service with a 3rd 
> party VOIP 
> > provider.  We have applied a very simple QoS policy (below) 
> to several 
> > customers interfaces on our Cisco 7206VXR's as well as the 
> CPE.  One 
> > customer in particular is complaining of frequent problems. 
>  We could 
> > not find anything real obvious of why they are having 
> issues.  Traffic 
> > on the norm is about 200-300k on a full T1 which should not even 
> > warrant needing the QoS in place.  From what I understand and have 
> > read on the Qos config below - it will only get applied as 
> the circuit 
> > starts to get congested. We put some real time traffic 
> monitors on the 
> > customers interface and saw a few real short spikes almost 
> maxing out 
> > the circuit.  Is it possible for the circuit to experience a really 
> > quick burst of traffic that doesn't allow the QoS policy to 
> "kick-in" 
> > quick enough so the customer experiences some drops ?  
> Anyone have any 
> > ideas on how to best troubleshoot or determine this problem 
> ?  Should 
> > we consider reserving a fixed amount of bandwidth vs the 
> config below.  
> > Could the output drops be contributing to this problem ?  
> Any pointers 
> > would be appreciated.
> >  
> > Thanks
> > Eric
> >  
> >  
> > class-map match-any VOIP
> >   match protocol rtp
> >   match protocol sip
> > !
> > policy-map voice
> >   class VOIP
> >    priority percent 65
> >    set ip precedence 5
> > 
> > interface Serialx/x/x
> >  bandwidth 1544
> >  ip address x.x.x
> >  ip flow ingress
> >  ip nbar protocol-discovery
> >  service-policy output voice
> >  encapsulation ppp
> >  no clns route-cache
> > 
> >  
> > show int Sx/x/x
> > Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 
> > 5222 Queueing strategy: weighted fair Output queue: 0/1000/64/5222 
> > (size/max total/threshold/drops) 
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net 
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > 
> > 
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net 
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> 
> 


_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/