Media Gateway Redundancy via Decoupled Control Bus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional mechanisms for redundancy in TDM-based service provider connections, such as those using mechanical relays and analog switches, face issues like high component and PCB costs, inferior reliability, slow switching times, impedance mismatches, and difficulties in hot swapping and reconfigurability, especially in high-density systems.
Innovation Solution
A media gateway architecture with a midplane bus decouples the hardware control interface from the control plane CPU, allowing bi-directional communication between a single Rear Transmission Module (RTM) and multiple Trunk Processing Modules (TPMs), and implements a signaling and control bus interface for arbitration and snooping, enabling finer resource scaling and hot standby redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical relays and analog switches are used for redundancy protection, then redundant connectivity is provided, but component cost and PCB real estate cost increase
Solution Approach 1:
The patent replaces mechanical relay switching mechanisms with digital signal processing and software-based redundancy management. The media gateway uses digital signal paths and electronic switching controlled by the TPM, eliminating the need for mechanical relays and analog switches while maintaining redundancy protection capabilities.
Solution Approach 2:
The patent extracts the control function from the hardware layer by implementing redundancy management in the control plane (TPM) rather than requiring dedicated hardware switching mechanisms. The control plane CPU manages redundancy through software, separating control logic from the physical switching hardware.
2Reliability
If mechanical relays are used for redundancy switching, then backup elements can replace active elements, but switching times are slow causing frame hits
Solution Approach 1:
The patent replaces slow mechanical relay switching with instantaneous digital switching controlled by the TPM. The digital signal paths can be reconfigured electronically without mechanical movement, achieving switching times measured in microseconds rather than milliseconds, thereby eliminating frame hits during failover.
Solution Approach 2:
The patent implements hot standby redundancy where backup TPMs are pre-configured and synchronized with active TPMs before failures occur. This preliminary preparation allows immediate takeover without switching delays, as the backup elements are already in a ready state to assume control instantly.
3Reliability
If relays are used in high-density systems, then redundancy is achieved, but card height must be increased
Solution Approach 1:
The patent extracts the redundancy function from the physical card level by implementing it in the control plane. Instead of requiring separate hardware redundancy at the card level, the system uses virtualization and software-based failover, allowing high-density card configurations without increasing individual card heights.
4Reliability
If conventional termination methods are used with active and backup cards, then proper termination is achieved, but impedance mismatches occur when cards are removed or inserted
Solution Approach 1:
The patent implements a universal termination approach where the RTM and bus interface are designed to work with any TPM regardless of its active or backup status. The bus interface and termination are independent of specific card configurations, allowing hot swapping without impedance mismatches as the termination remains consistent regardless of card presence or state.
5Reliability
If fixed 1 to 1 mapping between LIU/Framer hardware and CPU is used, then control information is properly managed, but scalability and reconfigurability are limited
Solution Approach 1:
The patent segments the control function by separating the control plane CPU (TPM) from the data plane hardware (RTM). This segmentation allows multiple TPMs to share access to multiple RTMs through the bus interface, enabling flexible configurations where N TPMs can manage M RTMs rather than requiring fixed 1-to-1 mappings. The arbitration mechanism enables dynamic allocation of control resources.
Solution Approach 2:
The patent implements a universal bus interface that allows any TPM to control any RTM through standardized communication protocols. This universal interface enables reconfigurability where TPMs can be dynamically assigned to different RTMs based on system needs, supporting hot standby redundancy and load balancing without requiring fixed hardware mappings.
Data Source
AI summary
In a media gateway, a single RTM is placed in bi-directional communication with a active TPM and also in bi-directional communication with a backup TPM. This is accomplished in part by implementation of a signaling and control bus interface between the LIU/Framer hardware of the RTM and the control processing unit (CPU) of the TPM. This interface provides for arbitration between multiple control sources, and for snooping of the input connection state and signaling information between the LIU/Framer and any other control entity. The interface also prevents contention by multiple control sources driving signal information to the LIU/Framer device.