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Cisco Bug: CSCut53373 - PGW initiates UBR while no QoS cahnge

Last Modified

Dec 24, 2016

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

17.0 17.2.0 19.2.d0 20.0.0 20.0.v0

Description (partial)

Symptom:
During VoLTE Call Hold testing, we have noticed that PGW is initiating Update bearer Request while there is no QoS change to report on GTPv2 interface.

Scenario:
- UE1 call UE2

- PCRF initiates RAR to activate a dedicated bearer on UE1 side
QoS: (GBR/MBR = 41000 bps for RTP + 2049 bps for RTCP) / QCI =1 / ARP = 6

- PGW intitates Create bearer request with GBR/MBR rounded up (44 Kbps)

- PCRF initiates RAR to activate a dedicated bearer on UE2 side
QoS: (GBR/MBR = 41000 bps for RTP + 2049 bps for RTCP) / QCI =1 / ARP = 6

- PGW intitates Create bearer request with GBR/MBR rounded up (44 Kbps)

- UE1 puts UE2 on Hold

- PCRF initiates a RAR for UE2 with new QoS 
QoS: (GBR/MBR = 41000 bps for RTP + 2050 bps for RTCP) / QCI =1 / ARP = 6)

- The rounded up bit-rates did not change (44 Kbps) but PGW initiates a UBR towards access 

PGW shall not initiate a UBR as there is no QoS change for GTPv2 interface.

Conditions:
Scenario:
- UE1 call UE2

- PCRF initiates RAR to activate a dedicated bearer on UE1 side
QoS: (GBR/MBR = 41000 bps for RTP + 2049 bps for RTCP) / QCI =1 / ARP = 6

- PGW intitates Create bearer request with GBR/MBR rounded up (44 Kbps)

- PCRF initiates RAR to activate a dedicated bearer on UE2 side
QoS: (GBR/MBR = 41000 bps for RTP + 2049 bps for RTCP) / QCI =1 / ARP = 6

- PGW intitates Create bearer request with GBR/MBR rounded up (44 Kbps)

- UE1 puts UE2 on Hold

- PCRF initiates a RAR for UE2 with new QoS 
QoS: (GBR/MBR = 41000 bps for RTP + 2050 bps for RTCP) / QCI =1 / ARP = 6)

- The rounded up bit-rates did not change (44 Kbps) but PGW initiates a UBR towards access
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