Purge Function
Function
-The Purge function allows an
SGSN to inform the HLR that it has deleted the MM and PDP contexts of a
detached MS
After
the MS detach from the network:
-The SGSN may delete the
MM/PDP context immediately
- the SGSN may keep the
MM/PDP context for some time of the detached MS
Mobility Management Timer Function
Periodic RA Update Timer
Function
-Monitors the periodic routing
area update procedure in the MS
-Upon its expiry, the MS shall
start a periodic routing area update procedure.
-The length of the timer is set in
SGSN; The value of the timer is sent to MS in attach accept message or routing
update accept message
Mobile Reachable Timer
Function
-Upon the expiry of this timer,
the MS is detached
-This is reset and started when
the state returns to STANDBY or PMM‑IDLE
-The timer shall be slightly
longer than the periodic RA update timer used by an MS
-The length of the timer is set in
SGSN
Purge Timer Function
-Allows the SGSN to inform the HLR
that it has deleted the MM and PDP contexts of a detached MS.
-The purge timer is set longer
than the mobile reachable timer
