How can I change parameter "frames per packet" in a CUBE

[Carlos Olortiga]

Hi guys,

I´m trying to communicate my CUCM with a Nortel PBX. Client have a Main office and remote offices, remotes use BCMs. I´m using a Cisco CUBE between my CUCM and the Nortel (CUBE talks H323 with CUCM and SIP with Nortel). Communication with Main office is fine, but with remote sides we have no audio (just ring). People from Nortel said, that they need to receive 3 frames per packets and no 2 as is default. So Is possible change the "frames per packets" by default fpp is 2 in G729, but can I change it?

Any help will be appreciated.

Thanks

Carlos Olórtiga        

[Ayodeji Okanlawon]

Carlos...

The first question is are you sure this is what the issue is..I have never heard of this before I must confess but I had like to explore other things..

1. First of all why are you not using a sip trunk between CUCM and CUBE--so you have a sip to sip connection? what version of cucm are you using

2. Have you looked at the sip traces on the CUBE to see why audio is not connecting..you can send

debug voip ccapi inout

debug ccsip messages

and sh run of your CUBE

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[Carlos Olortiga]

Hi Aok

Just like you, I never heard about change fpp. But Nortel people insist about this.

In fact flow is CUCM--h323--CUBE--sip--Nortel.

I´ll talk with the client to capture debugs. Sh run is attached

[Ayodeji Okanlawon]

From your config you are not offering any SDP to Nortel in your INVITEs. So you are doing Delayed offer from CUCM to CUBE and then to Nortel. This usually creates problems and I wont be surprised its whats creating the issue.

The challenge with your setup is you are going to need MTP to enable fast start on your H323 so that you can send EO to Nortel because CUBE doesnt support slow start to EO

I suggest you do the ff and test again..

1. change your h232 to SIP

2. configure early offer on CUBE

voice service voip

sip

ealry-offer forced

Test again and send debugs..

NB: if you dont change it to SIP, you will need to neable MTP on the h323 gateway to configure this on CUBE

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[Carlos Olortiga]

Thanks Aok,

Actually, outgoing faststart is already configured in H323 gateway in CUCM and I´m using an MTP (which is configured in the same CUBE but registered in CUCM). I would like to test some other things like "early-offer forced", unfortunally Nortel guys are really obstinate about the fpp parameter. So I need to know if is possible change it.

Somebody knows something about change this parameter in CUBE? Is it possible? Maybe some document about which codec parameters are adjustables in CUBE.

Thanks

Carlos Olórtiga

[Ayodeji Okanlawon]

Fast start to delayed offer on CUBE will  not work even if you set fpp as your Nortel are screaming for. You dont have a solution that can work. You have to do fast start to early offer on CUBE. Thats the minimum starting point.  So I suggest you trun on EO on CUBE first..then go from there...

The only thing you can change from CUCM point is your packet packetization period. The defualt is 20ms...If this is what they are referring to then this can be done from CUCM..but you should confirm that with them..You have two different packetization period, the default is 20ms, the other is 30ms.

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[Ayodeji Okanlawon]

I think I can confirm that this is indeed 30ms codec samples they are referring to...Each codec sample is 10ms, the default setting uses 2 10ms codec sample which 20ms...So 3 wil be 30 ms

The voice payload size can also be represented in terms of the codec samples. For example, a G.729 voice payload size of 20 ms (two 10 ms codec samples) represents a voice payload of 20 bytes [ (20 bytes * 8) / (20 ms) = 8 Kbps ]

You can also change this from CUCM or gateway..

In Cisco CallManager, the voice payload size per packet is configurable on a systemwide basis. This attribute is set in Cisco CallManager Administration (Service > Service Parameters > select_server > Cisco CallManager) with these three service parameters:

• PreferredG711MillisecondPacketSize—(Default setting: 20 ms. Available settings: 10, 20, and 30 ms.)

  
  

• PreferredG729MillisecondPacketSize—(Default setting: 20 ms. Available settings: 10, 20, 30, 40, 50, and 60 ms.)

  
  

• PreferredG723MillisecondPacketSize—(Default setting: 30 ms. Available settings: 30 and 60 ms.

  
  
• 
  

On the gateway:

Cisco-Router(config-dial-peer)#codec g729r8 bytes 30

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Carlos Olortiga]

Hi Aok,

I really appreciate your help. What you said, is exactly what I think. I will talk with Nortel guys, really I dont think it is the problem.

Thanks a lot

Carlos Olórtiga