voice traffic

[Anukalp S]

Hello, I have been running 20Mb mpls circuit over which i have formed GRE tunnel. My circuit goes choke most of the times. So i am planning to configure QoS and assign 5mb for voice traffic(i.e. for VOIP phone communication) and rest BW for others traffic. What would be best solution, should i police voice traffic under voice class map or PQ would be good.

Also how should i classify voice traffic for my voip phones. pls help.

[Joseph W. Doherty]

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Posting

From what you've described, there's insufficient information to suggest a possible "best" solution, but a good solution might be to shape for the 20 Mbps, and then allocate LLQ for your VoIP bear traffic and FQ for everything else.  Also, as you mention using a GRE tunnel, also define the tunnel to optimally deal with the lost of 24 bytes to GRE.

[Anukalp S]

Thanks Joseph as always for helping on QoS especially.

Actually we have two locations suppose A&B both locations are connected through MPLS but we configured GRE tunnel b/w A & B location.

MPLS BW is 20MB both sides. Also we have VOIP phones and other applications running both sides.

Since other applications like FTP,HTTP, mails occupies most of traffic hence faces voice disturbance talking on VOIP.

I want to assign sufficient BW to voice traffic lets say 5mb and rest BW for rest others traffic.

So i want your help in setting up QoS. Since i have configured GRE tunnel so i guess service policy should be applied over tunnel interface.

Pls help me in configuring QoS and allocating BW.

[Joseph W. Doherty]

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.

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Posting

For what Cisco devices and IOS images?

[Anukalp S]

Hi. both end devices are....

Cisco 2821    c2800nm-spservicesk9-mz.124-24.T.bin

Cisco 3845    c3845-spservicesk9-mz.124-20.T.bin

[Joseph W. Doherty]

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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.

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Posting

BTW, 20 Mbps can push the practical performance capacity of a 2821.

class-map match-any LLQ

!match your VoIP bearer traffic here

policy-map Shape20M

class class-default

shape average 17000000 !we're shaping 15% slower to allow for L2 overhead

service-policy Sample

policy-map Sample

class LLQ

priority percent 30

class class-default

bandwidth remaining percent 100

fair-queue

interface tunnel #

ip tcp adjust-mss 1436

ip mtu 1476

service-policy output Shape20M

tunnel path-mtu-discovery

keepalive 1

[Anukalp S]

Thanks Joseph.. Under class-map which traffic should i match.

Should it be "match ip dscp ef" or any ports range. pls suggest.

[Joseph W. Doherty]

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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.

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Posting

What you match on depends on what you can count on indicating the traffic you want to match, and only match to.  If you know all your VoIP bearer traffic is correctly marked with DSCP EF (and no other traffic is incorrectly marked with DSCP EF), matching the ToS value is ideal.

[Anukalp S]

Hi Joseph.. i am not doing currently marking for VOIP phones communication, what would be the good way to mark. If i dont mark VOIP traffic, can this be classified.

[Joseph W. Doherty · Accepted solution]

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Posting

I would recommend marking VoIP bearer traffic DSCP EF.

For VoIP signalling traffic, I would recommend using the RFC recommendation of DSCP CS5 although Cisco recommends using DSCP CS3.