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Webcast-Catalyst9k
New Member

QoS for VoIP - clarification needed in non-congested times

Hello,

I need a little clarification / assistance please. I have a cable modem connection that is 50mb down and 3mb up. The most I ever do in the download direction is around 8 to 10 mb. It's the upload that gets me sometimes when it spikes to around 2.5mbps up. I need to make sure my voip traffic ALWAYS gets sent on the wire first, regardless if there is congestion or not. Would the policy below work? If not, how should I tweak it.

Thank you,

class-map match-any QOS_REAL-TIME_VOIP

match access-group name VOIP_Traffic

ip access-list extended VOIP_Traffic

permit ip any any eq x.x.x.x

permit ip any any eq x.x.x.x

  policy-map VoIP

class QOS_REAL-TIME_VOIP

  priority 784

class class-default

  shape average 48000000

  bandwidth 50000000

Thank you,

7 REPLIES

QoS for VoIP - clarification needed in non-congested times

Your policy should help outbound traffic. You're guaranteeing 784k and then policing that traffic at 784k with the priority command. If you don't have anything else in the class default queue, voice can take it all. It only polices when there is other traffic in other queues waiting to be sent.

Everything else will match your default class. You need to configure this on the wan interface in the outbound direction:

int

service-policy output VoIP

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
Super Bronze

Re: QoS for VoIP - clarification needed in non-congested times

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

No, what you have won't work.

You would want something like:

policy-map shape4upstream

class class-default

shape average 2550000 !I'm shaping 15% under 3 Mbps to allow for L2 overhead

service-policy VoIP

policy-map VoIP

class QOS_REAL-TIME_VOIP

  priority 784

class class-default

fair-queue

[edit]

BTW, you would use the shape4upstream policy as the egress policy on your cable modem facing port

Re: QoS for VoIP - clarification needed in non-congested times

Joseph,

I have to ask...how is the policy map different from the original posted?

It still has a priority queue, but now it's embedded in another policy map. I guess the question is how does IOS treat the original map (which I thought should work fine) versus the one that you posted where it's embedded aside from shaping everything to the CIR?

*** Wait...did I just answer my own question? ***

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
New Member

QoS for VoIP - clarification needed in non-congested times

Good catch. My shaping was all wroing. It's outbudnd based is 3mb up! I originally shaped it for the 50mb down. Right?

The top policy is shaping the overal "tunnel" for 3mbs/2.5mb. Correct?

Super Bronze

Re: QoS for VoIP - clarification needed in non-congested times

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Correct and yes, although latter not for a "tunnel".

Super Bronze

Re: QoS for VoIP - clarification needed in non-congested times

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

*** Wait...did I just answer my own question? ***

You did

Additionally, the original policy's LLQ would never engage assuming the physical interface was greater than 48 Mbps, which would be a bit hard on a 3 Mbps uplink cap.

Re: QoS for VoIP - clarification needed in non-congested times

Thanks Joseph....I completely missed the shaped rate. Does it count that I'm on meds for a sinus issue? Lol...

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
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