Cisco Cisco ASR 5000
MTC Congestion Control
How It Works ▀
SGSN Administration Guide, StarOS Release 18 ▄
The maximum value for a standard T3312 timer value is 186 minutes and the new Extended T3312 timer maximum
value is 18600 minutes. Using the longer value for routing area updates reduces network load from periodic RAU
signaling.
value is 18600 minutes. Using the longer value for routing area updates reduces network load from periodic RAU
signaling.
Important:
Now, despite enabling the Extended T3312 timer in the SGSN’s configuration, the SGSN may be
prevented from sending the Extended T3312 timer value in messages as the SGSN also supports the “Subscribed
Periodic TAU/RAU Timer Withdrawn" flag .
Periodic TAU/RAU Timer Withdrawn" flag .
The SGSN also supports the Subscribed Periodic TAU-RAU Timer Withdrawn Flag in MAP DSD messages. When the
flag is set in MAP DSD messages, it indicates to the SGSN that the subscriber no longer has a subscription for the
“subscribed periodic RAU/TAU timer” (Extended T3312 timer) value, so
flag is set in MAP DSD messages, it indicates to the SGSN that the subscriber no longer has a subscription for the
“subscribed periodic RAU/TAU timer” (Extended T3312 timer) value, so
the SGSN will delete any subscribed periodic RAU/TAU timer value information when it is received from the
HLR, and
the SGSN will no longer send Extended T3312 in Attach/RAU Accept messages for that subscriber even if the
sending of the Extended T3312 is configured.
Limitations
The following resources for congestion detection are not yet supported:
License utilization
Max session count
Flows for SGSN Congestion Control
New Call Policy for Congestion
The following flowchart explains how new calls are handled, during congestion, based on configuration.