PGW Subnet Packet Forwarding via IP Mapping
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Solution Overview
Problem
LTE networks lack a defined mechanism for forwarding downlink packets to subnets hosted by cellular equipment, as the Packet Gateway (PGW) can only forward packets based on destination IP addresses and does not allocate addresses to subnets, resulting in dropped packets intended for subnets.
Innovation Solution
Establishing relationships between subnets and IP addresses at the PGW level and using a bearer to transport data to the hosting cellular equipment associated with the destination IP address, allowing for efficient packet forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PGW forwards packets based on destination IP addresses only, then the forwarding mechanism is simple and follows core network protocols, but packets intended for subnets hosted by cellular equipment cannot be routed and are dropped
Solution Approach 1:
The patent segments the addressing space by introducing a specific IP address range (10.96.0.0/11) reserved for subnet hosting. This allows the PGW to identify subnet-related packets through address recognition rather than complex routing logic, maintaining simplicity while improving reliability for subnet packet delivery
Solution Approach 2:
The patent introduces an intermediary addressing mechanism where the subnet host's IP address serves as a mediator to represent entire subnets. By assigning a gateway IP address to each subnet host and configuring the PGW with subnet-to-IP mappings, the system enables indirect packet routing to subnets without modifying the core forwarding protocol
2Reliability
If IP-in-IP encapsulation is used to create a tunnel between PGW and cellular equipment, then downlink packets can be forwarded to subnets, but significant overhead (more than 20 bytes) and cumbersome configuration operations are generated
Solution Approach 1:
The patent extracts the tunneling overhead by eliminating the need for IP-in-IP encapsulation. Instead of wrapping packets in additional IP headers, the solution uses direct IP routing based on the subnet host's gateway address, removing the 20+ byte overhead while maintaining reliable downlink delivery
Solution Approach 2:
The patent uses a lightweight addressing scheme where the PGW maintains a simple mapping table of subnet-to-IP addresses. This disposable lookup mechanism replaces complex tunnel configuration, requiring minimal memory and processing while achieving the same packet forwarding goal
3Reliability
If IP-in-IP encapsulation is used for tunneling, then packet forwarding to subnets is enabled, but packet losses might occur and significant overhead is generated
Solution Approach 1:
The patent removes the encapsulation overhead entirely by using direct IP routing. Packets are forwarded using the subnet host's gateway IP address as the destination, eliminating the need for outer IP headers and reducing overhead by more than 20 bytes per packet while maintaining delivery reliability
4Adaptability or versatility
If the PGW allocates IP addresses to subnets, then subnets become addressable and packets can be forwarded, but the PGW's function extends beyond its standard role of delivering packets to cellular equipment
Solution Approach 1:
The patent enables the PGW to perform multiple functions: standard cellular equipment packet delivery and subnet packet forwarding. By using the same IP address allocation mechanism for both purposes and maintaining a unified forwarding table, the PGW achieves versatility without significant complexity increase
Solution Approach 2:
The patent segments the addressing space to reserve a specific range (10.96.0.0/11) for subnet hosting. This allows the PGW to distinguish between regular cellular equipment addresses and subnet gateway addresses, enabling differentiated handling while maintaining a single unified forwarding mechanism
Data Source
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AI summary
There is described therein a method of forwarding packets to at least one subnet hosted by a LTE cellular equipment. The forwarding of packets destinated to subnets hosted by cellular equipment's is accomplished by defining relationships between subnets and cellular equipment's IP addresses at the PGW level and by using a bearer to transport the data from the PGW to a hosting cellular equipment associated to the destination.