ePDG S2b Piggybacking Support

Feature Information

Summary Data

Status:

New Feature

Introduced-In Release:

21.2

Modified-In Release(s):

ePDG

Applicable Product(s):

Cisco ASR 5500, VPC-SI, VPC-DI, UGP

Customer Specific:

No

Default Setting:

Disabled

CDETS ID(s)

CSCvc97504

Related Changes in this Release:

NA

Related Documentation:

ePDG Admin Guide, CLI Ref Guide and RCR

Revision History


Important

Revision history details are not provided for features introduced before release 21.2.

Revision Details

Release

Release Date

New in this release.

21.2

April 27, 2017

Feature Description

During LTE to WiFi handover, if Create Bearer Request reaches ePDG before Create Session Response, then it is dropped, as dedicated bearer is created only after session establishment is done. In this scenario, PGW will try to Create Bearer Request after 3 seconds, which in turn delays bearer creation.

S2b piggybacking resolves this issue by sending Create Session Response and Create Bearer Request in one message from PGW so that ePDG can process sequentially. This feature is nonstandard feature (non-3GPP). S2b Piggybacking support is controlled by CLI present under call-control-profile, this is disabled by default.

Assumptions and Limitations

  1. Piggybacking Supported flag will be set for both initial attach and handoff sessions.

  2. Only Create Bearer Request and Create Session Response messages will be supported as piggybacked during session creation.

Configuring ePDG S2b Piggybacking Support

Use the below configuration to configure Piggybacking Support. A new key word wlan piggybacking is introduced to support this feature. 
config 
               call-control-profile call_control_progile_name  
                 [remove] wlan piggybacking  
              exit  
              exit

Monitoring and Troubleshooting the S2B Piggybacking Support

Below show command output is introduced to support s2b Piggybacking:

show call-control-profile full { name profile_name | all }

WLAN Access:

  • piggybacking

show subscriber full

  • Piggybacking Supported