ATM Cell Switch Commands for STM Channel State Updates
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Solution Overview
Problem
Existing methods for carrying TDM traffic over ATM networks, such as E1 streams, are inefficient and lossy due to the slow-reacting busy-map system, which cannot quickly update channel states and results in delayed switching and lost data.
Innovation Solution
Incorporating switch commands within ATM cells to indicate changes in STM channel activation states, allowing for immediate state changes and reduced overhead, with optional error detection and correction mechanisms to ensure accurate channel management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the busy-map system is used to manage STM channel states over ATM, then channel state tracking is implemented, but the system reacts slowly and causes data loss due to delayed updates
Solution Approach 1:
The patent applies preliminary action by embedding switch commands in advance within ATM cells to indicate upcoming channel state changes. This allows the receiver to prepare for state transitions before they occur, eliminating the reactive delay inherent in the busy-map system and preventing data loss during channel activation/deactivation transitions.
Solution Approach 2:
The patent introduces switch commands as an intermediary mechanism between the transmitter and receiver to convey channel state information. These commands act as a mediator that carries state change indicators directly within the data stream, enabling faster and more reliable state tracking compared to the periodic busy-map approach.
2Productivity
If the busy-map system is used to manage STM channels, then channel activation is tracked, but bandwidth utilization is reduced due to overhead and slow response
Solution Approach 1:
The patent merges the channel state management function with the existing ATM cell structure by embedding switch commands within the cell payload. This integration eliminates the need for separate busy-map messages and reduces overhead, thereby improving bandwidth utilization while maintaining manageable complexity through reuse of existing protocols.
Solution Approach 2:
The patent changes the parameter representation by using compact switch commands that encode channel state transitions in a more efficient format than the traditional busy-map. This parameter optimization reduces the overhead required for channel management and enables faster processing, directly improving bandwidth utilization efficiency.
Data Source
AI summary
In a communications system a transmitter is arranged to transmit asynchronous transfer mode (ATM) cells in which synchronous transfer mode (STM) channels are assembled. In order to minimize the bandwidth required at lease some of the ATM cells include one or more switch command(s) (12) that indicate a change in the activation state of one or more STM channels (11-0 to 11-n).The switch commands (12) and STM channels (11) fill the ATM cell from opposite ends of the cell.Activate switch commands comprise two bytes, a high byte including a pointer (18) pointing to the start of a block of STM channels (11) and a low byte that includes a pointer (19) that points to the channel within a block of STM channels (11) to which the switch command applies.