GPRS PDP Context Timeout Management
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Solution Overview
Problem
In GPRS networks, hanging Packet Data Protocol (PDP) contexts occur due to timing mismatches between SGSN and GGSN nodes, leading to path failures and alarms, as the SGSN times out before the GGSN completes PDP context creation, especially during temporary congestion.
Innovation Solution
Incorporating a time-out period in the request message to create a PDP context and including a Network Service Access Point Identifier (NSAPI) in the response message to allow the GGSN to adjust its timeout and prevent hanging contexts, enabling timely responses and deletion of redundant contexts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SGSN uses a fixed N3-T3 timeout value, then the configuration is simple and manageable, but hanging PDP contexts occur when GGSN processing time exceeds the timeout value
Solution Approach 1:
The patent applies dynamics by making the timeout value adjustable and adaptive. The GGSN can modify the timeout parameter dynamically based on its current processing load and response time capabilities. This allows the system to adapt to varying network conditions and GGSN processing speeds, preventing hanging contexts while maintaining operational flexibility.
Solution Approach 2:
The patent implements feedback through the timeout modification mechanism. The GGSN monitors its own processing performance and feeds back this information by adjusting the timeout value sent to the SGSN. This feedback loop ensures that the timeout value reflects actual system conditions, improving reliability without requiring complex centralized configuration.
2Loss of time
If the GGSN processes PDP context creation quickly, then the response time is short and path failures are avoided, but complex processing tasks like RADIUS authentication cannot be completed
Solution Approach 1:
The patent uses dynamics by allowing the timeout value to vary based on the specific processing task. For simple contexts, the timeout remains short; for complex tasks involving RADIUS authentication or PCRF interactions, the GGSN extends the timeout value appropriately. This dynamic adjustment enables the system to handle diverse processing requirements without compromising either speed or completeness.
Solution Approach 2:
The patent applies parameter changes by modifying the timeout parameter based on the processing complexity. The GGSN assesses the required processing time for each PDP context creation request and adjusts the timeout parameter accordingly. This allows the system to accommodate varying task complexities while maintaining efficient processing for simpler operations.
3Reliability
If the SGSN rejects PDP context creation on timeout, then hanging contexts are avoided, but redundant GGSN attempts and path failures occur
Solution Approach 1:
The patent implements feedback by having the GGSN actively communicate its processing status and expected completion time to the SGSN through the modified timeout parameter. This feedback mechanism allows the SGSN to adjust its behavior accordingly - either waiting for the extended timeout or selecting alternative GGSNs - without prematurely rejecting valid context creation requests, thereby improving both reliability and efficiency.
Solution Approach 2:
The patent applies preliminary action by having the GGSN assess and declare its required processing time in advance through the timeout parameter modification. This allows the SGSN to make informed decisions about whether to wait for this specific GGSN or attempt alternative routes, preventing both premature rejections and unnecessary waiting.
Data Source
AI summary
A method and system for avoiding hanging Packet Data Protocol (PDP) contexts in a General Packet Radio Service (GPRS) network. A time-out period is included in a request message to create a PDP context. The request message is transmitted from a first GPRS Support Node (GSN) to a second GSN. The second GSN receives the request message and transmits a response message to the first GSN. If the second GSN is unable to create the PDP context within the time-out period, the response message informs the first GSN that creation of the PDP context has been aborted. A Network Service Access Point Identifier (NSAPI) may be included in the response message so that the first GSN may request the second GSN to delete the request for creating the PDP context after a N3-T3 timeout of the first GSN has expired.