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Cisco Bug: CSCvi72808 - CUBE changes the payload type (PT) of audio packets from 96 to 98 without any renegotiation

Last Modified

Jul 17, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

Denali-16.3.5

Description (partial)

Symptom:
CUBE changes the payload type (PT) of audio packets from 96 to 98 without any renegotiation

During the initial call setup, CUBE negotiated PT 96 for audio codec mpeg4-generic (aacld) towards both call legs. CUBE is receiving and forwarding RTP packets with PT 96 for audio to both call legs for the initial few seconds till it receives a REINVITE from SME. CUBE is getting a REINVITE from SME with PT 96 is being advertised for both audio and video connections, which is triggering the problem and changes the PT to 98. In the signaling, CUBE is still negotiating PT 96 for audio, however, CUBE starts sending audio RTP packets with PT 98 towards CMS endpoint. This is causing one-way audio.

SDP in the REINIVTE from SME/CUCM: PT 96 is present in Audio and Video M lines.

m=audio 44700 RTP/AVP 96 108 9 99 100 0 8 15 18 101
m=video 44702 RTP/AVP 97 126 114 96 34 31
m=application 44706 UDP/BFCP *
m=video 44704 RTP/AVP 97 126 114 96 34

CUBE is changing PT to 98 in the CUBE debug;

011278: *Mar 20 10:53:18.599: //-1/xxxxxxxxxxxx/SIP/Info/info/1/sipSPIUpdateDynamicPayloadunused: Unreserving dynamic payload type 98

This behavior of CUBE is causing one-way audio. We observed this in ISR G2 and G3 platforms.

Conditions:
When previously negotiated audio Payload Type is present in both Audio and Video M-lines
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