Cisco Cisco Packet Data Gateway (PDG) Documentation Roadmaps
New In This 8.0 Release
GGSN Features ▀
Cisco ASR 5000 Series Product Overview ▄
OL-22937-01
License Keys
Requires separate license key.
Benefits
Direct tunnel improves the user experience (e.g. expedited web page delivery, reduced round trip delay for
conversational services, etc.) by eliminating SGSN tunnel ‗switching‘ latency from the user plane. An additional
advantage of Direct Tunnel from an operational and capital expenditure perspective is that direct tunnel optimizes the
usage of user plane resources by removing the requirement for user plane processing on the SGSN.
conversational services, etc.) by eliminating SGSN tunnel ‗switching‘ latency from the user plane. An additional
advantage of Direct Tunnel from an operational and capital expenditure perspective is that direct tunnel optimizes the
usage of user plane resources by removing the requirement for user plane processing on the SGSN.
Description
The Direct Tunnel architecture allows the establishment of a direct user plane tunnel between the RAN and the GGSN,
bypassing the SGSN. The SGSN continues to handle the control plane signalling and typical makes the decision to
establish Direct Tunnel at PDP Context Activation. A Direct Tunnel is achieved at PDP context activation by the SGSN
establishing a user plane (GTP-U) tunnel directly between RNC and GGSN (using an Update PDP Context Request
towards the GGSN).
bypassing the SGSN. The SGSN continues to handle the control plane signalling and typical makes the decision to
establish Direct Tunnel at PDP Context Activation. A Direct Tunnel is achieved at PDP context activation by the SGSN
establishing a user plane (GTP-U) tunnel directly between RNC and GGSN (using an Update PDP Context Request
towards the GGSN).
The following figure illustrates the working of direct Tunnel between RNC and GGSN.
Figure 3.
Direct Tunnel Support in GGSN
../../../GRAPHICS/Production/SGSN/SGSN-Direct-Tunnel_v2.wmf
A major consequence of deploying Direct Tunnel is that it produces a significant increase in control plane load on both
the SGSN and GGSN components of the packet core. It is therefore of paramount importance to a wireless operator to
ensure that the deployed GGSNs are capable of handling the additional control plane loads introduced of part of Direct
Tunnel deployment. The GGSN and SGSN offers massive control plane transaction capabilities, ensuring system
control plane capacity will not be a capacity limiting factor once Direct Tunnel is deployed.
the SGSN and GGSN components of the packet core. It is therefore of paramount importance to a wireless operator to
ensure that the deployed GGSNs are capable of handling the additional control plane loads introduced of part of Direct
Tunnel deployment. The GGSN and SGSN offers massive control plane transaction capabilities, ensuring system
control plane capacity will not be a capacity limiting factor once Direct Tunnel is deployed.
Direct Tunnel Support
TP PR = 4218, ST16 PR = 47324
License Keys
Requires separate license key.
Hard Disk Storage for CDR Files
A hard disk has been introduced in the ASR 5000 to add storage capability.