DiffServer and G729 or/and G711 codec

Hello to all,

I don’t understand how the diffserver option works.
I need to give better VOIP to just one SM out of 20 linked one AP.
They have a SIP box to receive calls and make calls over the internet.

The main cisco router has QOS and a T1 to the internet.

The AP is configure in Hardware Scheduling w/ ver 7.3.6.
The SM has a CIR of 384Kbps and MIR 512Kbps, Hi Priority Channel is enable.

What are the code point settings on the SM for a VoIP using 729 or 711 codec to work?


Most Voip Equipment allow you to setup SIP TOS and RTP QOS Vaules

This will flag the packets leaving the device as hight priority.

On canopy are 56 and 48

So in our Sipura devices we flag SIP TOS as 0x30
and RTP TOS as 0x38

Those are hex vaules for decimal of 48 and 56

Inside the SM under uplink you should see somthing like this

VC: 055 : CoS: 00
Queue Overflow Cnt : 0
inoctets Cnt : 0
inucastpkts Cnt : 531223
innucastpkts Cnt : 0
indiscards Cnt : 0
inerrors Cnt : 0
outoctets Cnt : 265674614
outucastpkts Cnt : 403965
outnucastpkts Cnt : 511
outdiscards Cnt : 0
outerrors Cnt : 0
VC: 252 : CoS: 01
Queue Overflow Cnt : 0
inoctets Cnt : 0
inucastpkts Cnt : 455
innucastpkts Cnt : 0
indiscards Cnt : 0
inerrors Cnt : 0
outoctets Cnt : 115048
outucastpkts Cnt : 0
outnucastpkts Cnt : 0
outdiscards Cnt : 0
outerrors Cnt : 0

The VC252 is the high priority for that SM. You can also select the luid in the ap and look at the down stats from there.

This will allow these packets to move through the canopy system on the high priority channel before any other packets.

Hope this helps.

PS in order to see those vaules in the sm the ap must be setup correctly.

Each ISP has different methods. IE, BAM PRIZM etc…

I don’t want to understand this!

I don’t have access to the SIP service provider box. Does someone have access to vonage SIP box? I don’t think no one has.

Best way should be something link this is the High Priority sample for g.711 or g.729. Change the diffserver values to this.

That’s all I want.
Can someone help?

I am not sure what vonage flags their packets as.

Have you moved their path to HWS at all RF links?
Have you enabled the Hi Priority Channel on their SM?

Yes, I have Hardware Scheduling enable on the AP and all the SU.
Yes That Subscriber Units has Hi Priority enable
Out of the 20 SU this is the only one that has Hi Priority enable.

They know not to use the internet or do downloads while they are talking on the phone.

At time the voice breaks, that’s what the client said.

how many SM to you have registerd to that AP.

Then how many AP’s do you have on that cluster feeding down a BH.

Remeber there is a PPS limit on the AP’s and BH’s and depending on how the BH are configured you could be maxing out the pps some where.

What is the latency from the client to the voice gateway ?

Connected to that AP, I only have 18 SM.
I have 2 Motorola AP on the CMM, they are 900MHz advantage.
And about 8 more PTP, PTM, on that location. But max bandwidth usage is 3mbps, all routing.
The latency from the Internet Main Router ( Cisco 2600 ) to the VoIP SIP box is 25 ms. average.

I was heading down the line of maxing out your packets per second (pps)
with canopy you are limited to 3000 on the BH, if you try to exceed that then you will get packet drops, this could cause quality issues with voice.

Depending on Codec and settings you could require between 40 to 400pps for a voice call.


The Cisco 2621 can do a max of 25K pps and the Cisco 2950 can do 6.6 million pps.

I don’t know the data for the SixNet switch ( CMM Switxh ). But I don’t think it’s a pps problem. Out of the 18 SM, 15 are doing telnet aplications and the other is limited to e-mails the other has internet acces limited to 256Kbps CIR and 384Kbps MIR. The one in question has internet access to 384Kbps CIR 512 MIR.

if you run a continious ping from the client back to the VOIP gateway are seeing any major fluctuations in latency.

enable high channel priority on ap and sm. change diffserve 14 and 30 to priority 6.

that should help your voip.

That’s what I wanted.

That works


J Fernandez

Keep in mind that ToS settings are usually represented as HEX and DiffServ as decimal. Here’s the short method for converting…

Use the calculator that comes with Windows. Under “view” change the setting to scientific.

To convert from ToS in HEX to Diffserv in decimal:
Change the calculator the HEX
Enter the ToS value
Change the calculator to decimal
divide by 4 (always truncate the number…don’t round)

0xB8 = 184, 184/4=46
0xBA = 186, 186/4=46.5 truncated to 46

ToS values of B8 and BA are both codepoint 46. Remember the two least significant values are not considered for DiffServ.

To convert from Diffserv in decimal to ToS in HEX:
Change the calculator to decimal
Enter the DiffServ Codepoint
Multiply by 4
Change the calculator to HEX


It’s quick and easy.