Cisco Cisco ASR 5000
Topology-based Gateway Selection
▀ Feature Description
▄ SGSN Administration Guide, StarOS Release 18
Feature Description
Topology-based GGSN or co-located P-GW selection is provided in the Gn/Gp-SGSN and topology-based P-GW and
S-GW selection is provided in the S4-SGSN.
S-GW selection is provided in the S4-SGSN.
Selecting a co-located or topologically (geographically) close GW node results in lower latency and prevents
unnecessary traversal of the packets in the network.
unnecessary traversal of the packets in the network.
For the Gn/Gp-SGSN
For the Gn/Gp-SGSN, topology-based GW selection is supported for the following call flows:
1st Primary Activation to select the GGSN or co-located P-GW that is topologically (geographically) closer to
the SGSN.
Subsequent Primary Activation to select the GGSN or co-located P-GW that is topologically closer to the
SGSN.
For the S4-SGSN
For the S4-SGSN, topology-based GW selection is supported for the following call flows:
1st Primary Activation to select the topologically closer or co-located S-GW / P-GW node pair.
Subsequent Primary Activation to select the P-GW that is topologically closer or co-located to the already
selected SGW.
Intra RAU to select the S-GW that is topologically closer or co-located to the already selected P-GW.
Intra SRNS to select the S-GW that is topologically closer or co-located to the already selected P-GW.
Inter New SGSN RAU to select the S-GW that is topologically closer or co-located to the already selected P-
GW.
Inter New SRNS to select the S-GW that is topologically closer or co-located to the already selected P-GW.
IRAT to select the S-GW that is topologically closer or co-located to the already selected P-GW.