SGSN Pool, also known as Gb Flex,
enables multiple SGSNs to form a SGSN pool. A BSC belonging to an SGSN pool
area is connected to all SGSNs in the related SGSN pool. The resources and load
are shared by all the SGSNs in the pool, thus balancing the traffic load and reducing
inter-SGSN handovers.
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When
more SGSN capacity is required, the SGSNs can be added without the replanning of
the radio network. Therefore, a lot of configuration efforts can be avoided.
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The
SGSN Pool feature supports SGSN redundancy. If an SGSN in the SGSN pool is
faulty, the remaining SGSNs will keep serving the MSs located within the SGSN
pool area. In a non-pooled case, the complete SGSN service area is lost in case
of an SGSN failure.
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An SGSN in the SGSN pool serves all the
routing areas (RAs) in the SGSN pool area. This means that no inter-SGSN RA
update is needed, because an MS is registered in the same SGSN as long as it is
located within the SGSN pool area. This increases the QoS of GPRSfor the
end-user.
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The
capacity dimensioning for an SGSN pool can be made according to the busy hour traffic
of the whole SGSN pool area. This is in contrast to a non-pooled case where
each SGSN has to be dimensioned according to the busy hour traffic of the area
served by the specific SGSN. As the busy hour traffic may occur at different
time for different SGSNs,more SGSN capacity may be needed in total for the
non-pooled case. Therefore, SGSN Pool helps to improve network capacity and
save capital expenditure (CAPEX).
SGSN Pool is enabled when the parameter
Allow SGSN Pool is set to Yes. If
the SGSN Pool feature is enabled at the BSC, the P-TMSI reassignment function
must be enabled at the SGSN