Active-Active TDM Packet Selection with Latency Asymmetry Control
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Solution Overview
Problem
Current telecommunications networks face challenges in maintaining symmetrical communication and minimizing latency asymmetry, particularly in time-division multiplexing (TDM) services, which are critical for applications like teleprotection, where failure of a single network link can lead to service disruption and unacceptable traffic hits.
Innovation Solution
The implementation of a network element that receives replicated TDM packets through multiple paths, selects a copy based on latency and jitter considerations, and inputs the selected packet into a jitter buffer to ensure hitless service delivery and minimize asymmetry, even with network link failures, by using multiple active paths over a packet-switched network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple active paths are used for TDM traffic over packet switched network, then service reliability is improved, but latency asymmetry increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing latency values for each path before actual TDM traffic transmission. The network element measures the latency of each path in advance (during a calibration phase) and stores these values. When selecting packets from multiple paths, the system uses these pre-known latency values to compensate for asymmetry, choosing packets from paths that will maintain symmetrical end-to-end latency. This resolves the contradiction by enabling reliable multi-path transmission while maintaining latency symmetry through advance preparation.
2Productivity
If packets are selected based on earliest arrival, then productivity is improved, but service symmetry deteriorates
Solution Approach 1:
The patent applies parameter changes by transforming the packet selection criterion from simple earliest-arrival-time to a composite parameter that includes both arrival time and pre-measured path latency. Instead of always selecting the first packet to arrive (which improves productivity but breaks symmetry), the system calculates an adjusted selection parameter that factors in the known latency characteristics of each path. This allows the system to maintain high processing speed while selecting packets that preserve service symmetry, resolving the contradiction between productivity and service symmetry.
Data Source
AI summary
A method for enabling enable use of multiple active paths for TDM traffic over a packet switched network, comprises: receiving at least two copies of a replicated packet including TDM information via at least two paths through the packet switched network, the at least two copies of the replicated packet including at least a first copy of the replicated packet received via a first of the at least two paths, and a second copy of the replicated packet received via a second of the at least two paths; selecting a copy of the replicated packet from among the at least two copies of the replicated packet; inputting the selected copy of the replicated packet to a jitter buffer; discarding unselected ones of the at least two copies of the replicated packet; and outputting the selected copy of the replicated packet from the jitter buffer to a TDM endpoint device.