Cisco Cisco Packet Data Gateway (PDG)
MME Changes in Release 17
MME Enhancements for 17.0 ▀
Release Change Reference, StarOS Release 17 ▄
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While storing the back-off timer expiry time, MME shall adjust the mobile reachability timer and/or implicit detach
timer. This is to make sure that the sum of the mobile reachability timer + implicit detach timer is greater than the back-
off timer duration.
timer. This is to make sure that the sum of the mobile reachability timer + implicit detach timer is greater than the back-
off timer duration.
The MME will store the DB for at least the EMM back-off timer duration even if the attach is rejected because of
congestion. The MME will not start any timer for EMM back-off. Instead, back-off timer expiry time will be stored in
the DB as the DB is stored for at least back-off timer duration.
congestion. The MME will not start any timer for EMM back-off. Instead, back-off timer expiry time will be stored in
the DB as the DB is stored for at least back-off timer duration.
If an EMM call is rejected due to congestion control for EMM, the DB created during ULA will not be cleared and the
purge timer will be started for a time period 10% greater than the back-off timer duration. This is done to make sure that
DB is available during back-off timer duration to reject any requests during this period and also to avoid the HSS
signaling again if the UE comes back immediately after the back-off timer duration.
purge timer will be started for a time period 10% greater than the back-off timer duration. This is done to make sure that
DB is available during back-off timer duration to reject any requests during this period and also to avoid the HSS
signaling again if the UE comes back immediately after the back-off timer duration.
The MME will not reject any TAU received in EMM-CONNECTED state.
The MME will not reject any requests related to handovers as part of this feature even if EMM back-off timer is
running.
running.
The MME will drop attach requests received during congestion while EMM back-off timer is running based on
configuration in congestion-action-profile. For example, if configuration is enabled to reject new call only when low
priority indication is set and the UE comes without low priority indication while back off timer is running, the MME
will accept the new call attempt from the UE.
configuration in congestion-action-profile. For example, if configuration is enabled to reject new call only when low
priority indication is set and the UE comes without low priority indication while back off timer is running, the MME
will accept the new call attempt from the UE.
The MME will not reject/drop attach requests received even if EMM back-off timer is running if the congestion gets
cleared.
cleared.
The MME will forward SGS paging requests received from MSC for a UE attached in MME even if back-off timer is
running.
running.
ESM T3396 Timer
The MME now allows configuration of the T3396 back-off timer value.
With this feature, when any ESM request is rejected because of congestion, the reject will have ESM cause “Insufficient
resources” and will include a back-off timer IE (T3396). This back-off timer is chosen randomly and will be 10% below
or above the configured T3396 timer value.
resources” and will include a back-off timer IE (T3396). This back-off timer is chosen randomly and will be 10% below
or above the configured T3396 timer value.
The MME will not start any timer for SM back-off, nor store the SM back-off timer expiry time. If an SM request is
received and if congestion exists, the request would be rejected based and a new random value will be sent as the ESM
back-off timer value.
received and if congestion exists, the request would be rejected based and a new random value will be sent as the ESM
back-off timer value.
The MME will reject any subsequent requests from the UE targeting to the same APN based on the presence of
congestion at that time and not based on the SM back-off time previously sent to the UE.
congestion at that time and not based on the SM back-off time previously sent to the UE.
If the ESM cause value is #26 “insufficient resources” or #27 “missing or unknown APN”, the MME will include a
value for timer T3396 in the reject message. If the ESM cause value is #26 “insufficient resources” and the request
message was sent by a UE accessing the network with access class 11 - 15 or if the request type in the PDN
CONNECTIVITY REQUEST message was set to “emergency”, the MME will not include a value for timer T3396.
value for timer T3396 in the reject message. If the ESM cause value is #26 “insufficient resources” and the request
message was sent by a UE accessing the network with access class 11 - 15 or if the request type in the PDN
CONNECTIVITY REQUEST message was set to “emergency”, the MME will not include a value for timer T3396.
Command Changes
emm
This command now includes a new keyword to configure the t3346 timeout value.
configure
context context_name