can I divide my Bandwidth dedicated for VoIP

[mintheinkyaw]

Hi All,

Please advice me what I wanted to do is possible or not.

I have 128 kbps Bandwidth leased line circuit to my branch office in Singapore and I would like to dedicated assign 64 kbps of my bandwidth for VoIP traffice. The rest traffic with go with another 64 kbps.

I am using cisco 1760 routers and is it possible to do?

Any advice will be appreciated.

[paolo bevilacqua]

Yes, use LLQ QoS for this.

class-map voice

match dscp ef

policy-map llq

class voice

priority 64

class class-default

fair-queue

interface serial x/y

service-policy output llq

after that, observe results with "show policy-map interface". If no packets matches class voice, your voice traffic is not marked dscp ef, as it should be so. either fix traffic or reconfig class voice.

Hope this helps, please rate post if it does!

[mintheinkyaw]

Hello Sir,

Thanks for your advice.

But I could not understand what is..

class class-default <-- and I also can not type this command in router.

please advice me if you have time.

Thanks,

[paolo bevilacqua]

That would all traffic not matching class voice, ive fair queueing. It is not really necessary to have that, but is beneficial expecially on slow links.

Which exact IOS are you using ?

[mintheinkyaw]

Hi,

IOS version is "C1700-IPVOICE-M (Version 12.3(7)XR3.

Thanks,

[paolo bevilacqua]

If you cannot upgrade IOS, just leave it without "class-default". Wath matters, is priority for voice.

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[mintheinkyaw]

I have two routers connected. So, do I need to configure for both sides?

Thanks.

[mintheinkyaw]

Bevilacqua,

I just configure on two Routers. Once I finised the configuration. I saw below output with not packets transfering.

Router#sh policy-map interface

Serial0/1

Service-policy output: llq

Class-map: voice (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: dscp ef

Queueing

Strict Priority

Output Queue: Conversation 40

Bandwidth 32 (kbps) Burst 800 (Bytes)

(pkts matched/bytes matched) 0/0

(total drops/bytes drops) 0/0

Class-map: class-default (match-any)

3269 packets, 2187341 bytes

5 minute offered rate 57000 bps, drop rate 0 bps

Match: any

Router#

After I made some ph calls. I can see below output showing packets transfering.

Router#sh policy-map interface

Serial0/1

Service-policy output: llq

Class-map: voice (match-all)

5045 packets, 322159 bytes

5 minute offered rate 5000 bps, drop rate 0 bps

Match: dscp ef

Queueing

Strict Priority

Output Queue: Conversation 40

Bandwidth 32 (kbps) Burst 800 (Bytes)

(pkts matched/bytes matched) 3115/128688

(total drops/bytes drops) 0/0

Class-map: class-default (match-any)

16895 packets, 10045657 bytes

5 minute offered rate 81000 bps, drop rate 0 bps

Match: any

Router#

So, is it working fine now? How can I check it is actually reserver the bandwidth for voice?

Thanks for your kind help.

[paolo bevilacqua]

Hi,

yes, it seems you are using a low bitrate codec, w/ vad.

You have reserved 32 kbps for voice. When there is no voice traffic, data can use that bandwidth.

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