PGW Context Preservation for SGW Restart Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Evolved Packet Core (EPC) networks, mobile terminated calls frequently fail when a Serving Gateway (SGW) restarts, as existing mechanisms fail to promptly recover bearer and mobility management contexts, leading to prolonged service unavailability.
Innovation Solution
The solution involves methods and signaling mechanisms for a Packet Gateway (PGW) and Serving Gateway (SGW) to maintain and relocate bearer and mobility management contexts after an SGW restart, using control plane signals and GTP messages to identify user entities and select new SGWs, ensuring seamless service continuity during SGW failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SGW restarts and existing mechanisms delete all PDN connection table data and MM bearer contexts, then the restarted SGW frees internal resources, but mobile terminated service cannot be delivered to the UE for a long time
Solution Approach 1:
The PGW maintains the PDN connection table data and MM bearer contexts in advance before the SGW restarts. When the SGW restarts, these pre-maintained contexts allow the system to quickly re-establish service without waiting for full context recovery, thereby reducing service unavailability duration while ensuring service reliability
Solution Approach 2:
The PGW acts as an intermediary that preserves the PDN connection table data and MM bearer contexts during SGW restart. By maintaining these critical data structures at the PGW level, the system can bridge the gap during SGW recovery, allowing faster service restoration without compromising the resource freeing benefits at the restarted SGW
2Loss of time
If the PGW maintains PDN connection table data and MM bearer contexts after SGW failure, then mobile terminated service can be restored faster, but system complexity increases
Solution Approach 1:
The patent merges the maintenance of PDN connection table data and MM bearer contexts at the PGW level, combining these functions into a single node that can serve multiple purposes. This consolidation allows faster context recovery without proportionally increasing overall system complexity, as the PGW already exists in the architecture and can be enhanced to perform additional maintenance functions
Solution Approach 2:
The PGW is designed to perform multiple functions: it serves as the packet gateway while also maintaining PDN connection table data and MM bearer contexts during SGW failures. This multi-functionality allows the same node to provide both routing services and context preservation, reducing the need for additional dedicated components and thereby limiting the increase in system complexity
Data Source
AI summary
In one aspect, a method for a packet gateway node (PGW) is disclosed. The PGW being adapted for (a) communicating with at least a serving gateway node, SGW, (b) receiving and forwarding downlink data packets to a user entity, UE, and (c) communicating with a mobility management entity, MME. In one embodiment, the method comprises: the PGW, when receiving a downlink user plane data packet destined for the UE on a Packet Data Network, PDN, connection associated with a restarted SGW, determining if the PDN connection has not yet been relocated to a new SGW, and, if so, selecting at least one SGW from a set of SGWs including the restarted SGW or another SGW and transmitting a control plane signal to at least one of the selected SGWs, the control plane signal identifying at least the UE.