Cisco Cisco ASR 5000
Direct Tunnelling for the S4-SGSN
▀ Feature Description
▄ SGSN Administration Guide, StarOS Release 18
Feature Description
The amount of user plane data will increase significantly during the next few years because of High Speed Packet
Access (HSPA) and IP Multimedia Subsystem technologies. Direct tunnelling of user plane data between the RNC and
the S-GW can be employed to scale UMTS system architecture to support higher traffic rates.
Access (HSPA) and IP Multimedia Subsystem technologies. Direct tunnelling of user plane data between the RNC and
the S-GW can be employed to scale UMTS system architecture to support higher traffic rates.
DT offers a solution that optimizes core architecture without impact to UEs and can be deployed independently of the
LTE/SAE architecture.
LTE/SAE architecture.
S4-SGSN now supports establishment of a GTP-U direct tunnel between an RNC and the S-GW under the scenarios
listed below:
listed below:
Primary PDP activation
Secondary PDP activation
Service Request Procedure
Intra SGSN Routing Area Update without S-GW change
Intra SGSN Routing Area Update with S-GW change
Intra SGSN SRNS relocation without S-GW change
Intra SGSN SRNS relocation with S-GW change
New SGSN SRNS relocation with S-GW change
New SGSN SRNS relocation without S-GW relocation
E-UTRAN-to-UTRAN Iu mode IRAT handover with application of S12U FTEID for Indirect Data Forwarding
Tunnels as well
UTRAN-to-E-UTRAN Iu mode IRAT handover with application of S12U FTEID for Indirect Data Forwarding
Tunnels as well
Network Initiated PDP Activation
Scenarios that vary at S4-SGSN when direct tunneling is enabled, as compared to DT on a 2G or 3G SGSN using the
Gn interface, include:
Gn interface, include:
RAB Release
Iu Release
Error Indication from RNC
Downlink Data Notification from S-GW
Downlink Data Error Indication from S-GW
MS Initiated PDP Modification
P-GW Initiated PDP Modification while the UE is IDLE
HLR/HSS Initiated PDP Modification
Session Recovery with Direct Tunnel
The above scenarios exhibit procedural differences in S4-SGSN when a direct tunnel is established.