[c-nsp] VOIP QOS

Mike Louis MLouis at nwnit.com
Mon Nov 12 12:43:07 EST 2007


Are you using the maximum bandwidth command on the interfaces heading to the customer and explicitly setting the bandwidth on the interface?

I see packet delayed in the default class, which is normal with shaping, but i don't see any drops. Maybe i am missing something.

Why arent you using LLQ on the voice side ? Do you not want to queue priority traffic out that interface and just mark and rate limit it?

one option would be to use

class VOIP
   set dscp ef
   priority 2000000

LLQ has a built in rate limiter.



________________________________________
From: cisco-nsp-bounces at puck.nether.net [cisco-nsp-bounces at puck.nether.net] On Behalf Of Jonathan Charles [jonvoip at gmail.com]
Sent: Monday, November 12, 2007 10:34 AM
To: Paul Stewart
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] VOIP QOS

Just a head's up, cuz Cisco changed this...

It used to be you would do EF for voip payload and AF31 for control.

Well, Cisco changed it and now voip control is using CS3, so you need
to do a match any for voip control and hit either.



J

On Nov 8, 2007 9:33 AM, Paul Stewart <paul at paulstewart.org> wrote:
> Hi there...
>
> I know this has been discussed several times and searched the archives...
> I'm being told by a client that this isn't working well.. my question is
> what is a better way to offer this?
>
> 5 Meg synchronous connection carrying VOIP (SIP/RTP) and general Internet
> traffic.  Want to prioritize the VOIP and carve out "up to" 2 meg of traffic
> when needed leaving "up to" 3 meg for general traffic... also want to be
> able to use 4 meg of general traffic when VOIP isn't using much etc....
>
> Cisco 2821 at customer premise with FE0/0 being the edge interface - Cisco
> 7206VXR on our side with customer connection coming off subinterface
> GigE0/0.101
>
> Between these devices is ethernet equipment that supports DSCP and is
> supposed to prioritize - below you'll see no congestion in place but on the
> VOIP side we're seeing dropped packets frequently that are not seen when we
> remove QOS from interfaces indicating something in this config is wrong....
>
> Any thoughts are appreciated...
>
> Both sides have the following applied outbound on the edge interface:
>
> class-map match-any VOIP
>  match protocol rtp
>  match protocol sip
> !
> !
> policy-map QOS-VOIP
>  class VOIP
>   set dscp ef
>   shape average 2000000
>  class class-default
>   set dscp default
>   shape average 3000000
>
>
>  FastEthernet0/0
>
>   Service-policy output: QOS-VOIP
>
>     Class-map: VOIP (match-any)
>       4649311 packets, 996776732 bytes
>       5 minute offered rate 401000 bps, drop rate 0 bps
>       Match: protocol rtp
>         4644189 packets, 993315456 bytes
>         5 minute rate 397000 bps
>       Match: protocol sip
>         5121 packets, 3461062 bytes
>         5 minute rate 4000 bps
>       QoS Set
>         dscp ef
>           Packets marked 4649311
>       Traffic Shaping
>            Target/Average   Byte   Sustain   Excess    Interval  Increment
>              Rate           Limit  bits/int  bits/int  (ms)      (bytes)
>           2000000/2000000   12500  50000     50000     25        6250
>
>         Adapt  Queue     Packets   Bytes     Packets   Bytes     Shaping
>         Active Depth                         Delayed   Delayed   Active
>         -      0         4649311   996776732 0         0         no
>
>     Class-map: class-default (match-any)
>       1687936 packets, 438092041 bytes
>       5 minute offered rate 120000 bps, drop rate 0 bps
>       Match: any
>       QoS Set
>         dscp default
>           Packets marked 1680145
>       Traffic Shaping
>            Target/Average   Byte   Sustain   Excess    Interval  Increment
>              Rate           Limit  bits/int  bits/int  (ms)      (bytes)
>           3000000/3000000   18750  75000     75000     25        9375
>
>         Adapt  Queue     Packets   Bytes     Packets   Bytes     Shaping
>         Active Depth                         Delayed   Delayed   Active
>         -      0         1687936   438092041 40206     48842063  no
>
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