Cisco Cisco Packet Data Gateway (PDG)
MME Changes in Release 16
▀ MME Enhancements for 16.0
▄ Release Change Reference, StarOS Release 16
292
CSCuj42615 - Purge requirement for PS -> CS handoff after SGSN Context
Transfer
Feature Changes
HSS Purge After SRVCC Handoff
The MME now supports a configuration capability to perform the Purge UE procedure to the HSS for UEs which
support Dual Transfer Mode (DTM). This feature is configurable via the CLI and is disabled by default. If configured,
the MME initiates an HSS Purge after the following two SRVCC Handoff (HO) scenarios:
support Dual Transfer Mode (DTM). This feature is configurable via the CLI and is disabled by default. If configured,
the MME initiates an HSS Purge after the following two SRVCC Handoff (HO) scenarios:
For SRVCC Handoff with PS Handoff support, the Purge S6a message is sent immediately after successful completion
of the Handoff. For this scenario, the configurable purge timer is not used.
of the Handoff. For this scenario, the configurable purge timer is not used.
For SRVCC Handoff without PS Handoff support, a configurable timer is initiated and the Purge S6a message is sent if
a SGSN Context Request is received prior to timer expiry. If a Context Failure occurs, no HSS Purge S6a message is
sent.
a SGSN Context Request is received prior to timer expiry. If a Context Failure occurs, no HSS Purge S6a message is
sent.
Customer Impact: This feature ensures the HSS has a reliable UE status on whether it is currently operating on the
LTE network.
LTE network.
Command Changes
policy srvcc purge-timer
This new command configures the MME to initiate an HSS Purge after the SRVCC HO where the UE supports DTM. It
also allows configuration of a purge timeout value in seconds.
also allows configuration of a purge timeout value in seconds.
configure
context ctxt_name
mme-service srvc_name
policy srvcc purge-timer seconds
[ no ] policy srvcc purge-timer
[ default ] policy srvcc
end
Notes:
purge-timer seconds
: defines how long in seconds the Purge Timer will run. This is applicable only for
SRVCC Handoff without PS Handoff support scenarios.
For example, if
purge-timer
is set to 20 seconds :
If the Context Transfer happens 10 seconds after SRVCC HO, the MME intiates an HSS Purge.
If the Context Transfer happens 30 seconds after SRVCC HO, the MME will NOT initiate an HSS Purge
because the Purge Timer has expired.
because the Purge Timer has expired.
seconds
: must be entered as an integer from 1 through 24000.