Issue on IOS MTP on Cisco ISR 4331

[tmohamudally]

Hi All,

I am facing a strange issue on some IOS MTP on Cisco ISR 4331. On my environment I have an IVR system. To reach this IVR,  MTP must be used. I have a pool of IOS MTP hosted on Cisco 2911 routers and Cisco ISR 4331 routers. When CUCM allocates an IOS MTP hosted on a Cisco 2911, every works fine. However when CUCM allocates an IOS MTP hosted on a Cisco ISR 4331, the greeting message of the IVR is not heard. I did multiple captures and found that in the case of the 4331 the IVR send the RTP stream to the MTP but the latter does not relay the RTP stream to the calling endpoint. 

I do not know if there any thing different between IOS MTP on Cisco 2911 and Cisco 4331. 

As a workaround I have removed the IOS MTP on the Cisco 4331 from the MRGL.

Has someone encountered anything like this?

[Chris Deren]

Can you post the configs of both routers?

Is codec passthrough configured under the MTP profile?

[tmohamudally]

Hi Chris,

Find below the configs:

Cisco 2911:

sccp local Port-channel1
sccp ccm 172.18.20.11 identifier 18 version 7.0
sccp ccm 172.20.20.11 identifier 20 version 7.0
sccp

sccp ccm group 10
associate ccm 18 priority 2
associate ccm 20 priority 3
associate profile 1 register HO_VOICEGW
!
sccp ccm group 20
associate ccm 18 priority 2
associate ccm 20 priority 3
associate profile 2 register MTP_HO_VOICEGW
!
dspfarm profile 1 transcode
codec g729r8
codec g729abr8
codec g729ar8
codec g711alaw
codec g711ulaw
maximum sessions 47
associate application SCCP
!
dspfarm profile 2 mtp

codec pass-through
codec g711ulaw
maximum sessions hardware 65
associate application SCCP

Cisco 4331:

sccp ccm 172.20.20.11 identifier 20 version 7.0
sccp ccm 172.18.20.11 identifier 18 version 7.0
sccp
!
sccp ccm group 11
bind interface Port-channel1
associate ccm 20 priority 1
associate ccm 18 priority 2
associate profile 1 register STJ_VGW2_MTP
!
sccp ccm group 10
bind interface Port-channel1
associate ccm 20 priority 1
associate ccm 18 priority 2
associate profile 2 register STJ_VGW2_XCODE
!
!
!
dspfarm profile 2 transcode
codec g711ulaw
codec g711alaw
codec g729abr8
codec g729ar8
codec g729r8
maximum sessions 16
associate application SCCP
!
dspfarm profile 1 mtp
codec pass-through
codec g711ulaw
maximum sessions software 100
associate application SCCP

[engmouafy]

Hello,

for the ISR 4331, the command (config)#sccp local Port-channel1 is missing.

the SDP is sent with 0.0.0.0 for RTP call leg connection with MTP.

BR,
Ismail Mouafy

[tmohamudally]

Hello,

In fact the command sccp local Port-channel1 is present. I missed it when I pasted the configuration in the post.

Sorry for that.

Thanks

Thierry

[Rajan]

Hi Thierry,

In Cisco 2911, hardware MTPs are configured whereas in Cisco 4331, you have configured IOS software MTPs. Can you try configuring hardware MTPs in 4331 as well.

2911

dspfarm profile 2 mtp
codec pass-through
codec g711ulaw
maximum sessions hardware 65

4331

dspfarm profile 1 mtp
codec pass-through
codec g711ulaw
maximum sessions software 100

HTH
Rajan
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[tmohamudally]

Hi,

I have configured the MTP as hardware on the 4331. The issue still happens. The RTP is not relayed to the caller.

Attached the RTP Stream which is not relayed by the MTP - I don't konw if it can be of some help.

Thanks

Thierry