Pdp Context Preservation - Cisco ASR 5000 series Product Overview

Serving GPRS Support Node (SGSN) Overview

PDP Context Preservation

The SGSN provides this functionality to facilitate efficient radio resource utilization. This functionality comes into play
on the following triggers:
RAB (Radio Access Bearer) Release Request
This is issued by the RAN to request the release of RABs associated with specific PDP contexts. The SGSN
responds with a RAB assignment request, waits for the RAB assignment response and marks the RAB as
having been released. The retention of the PDP contexts is controlled by configuration at the SGSN. If the PDP
contexts are retained the SGSN is capable of receiving downlink packets on them.
Iu Release Request
The RAN issues an Iu release request to release all RABs of an MN and the Iu connection. The retention of the
PDP contexts is controlled by configuration at the SGSN. When PDP contexts are retained the SGSN is
capable of receiving downlink packets on them.
When PDP contexts are preserved, the RABs can be restored on a service request from the MN without having
to go through the PDP context establishment process again. The service request is issued by the MN either
when it has some data to send or in response to a paging request, on downlink data, from the SGSN.
Charging
To provide efficient and accurate billing for calls and SMS passing through the SGSN, the system:
allows the configuration of multiple CGFs and GSSs and their relative priorities.
implements the standardized Ga interface based on GTPP over UDP and all relevant charging information as
defined in 3GPP TS.32.251 v 7.2.0.
SGSN Call Detail Records (S-CDRs)
These charging records are generated for PDP contexts established by the SGSN. They contain attributes as defined in
TS 32.251 v7.2.0.
Mobility Call Detail Records (M-CDRs)
These charging records are generated by the SGSN's mobility management (MM) component and correspond to the
mobility states. They contain attributes as defined in 3GPP TS 32.251 v7.2.0.
OL-22938-02
Features and Functionality - Basic ▀
Cisco ASR 5000 Series Product Overview ▄