Round Trip Delay KPI Monitoring via User Plane Probe Session
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Solution Overview
Problem
Current methods for measuring round trip delay in communication networks are prohibitively expensive and impractical, as they require extensive logging of timestamps across multiple network elements, which is CPU-intensive and complex, especially when dealing with encrypted packets and large-scale networks.
Innovation Solution
A method involving the transmission of a loopback message with a probe session indicator, where timestamps are logged at each network element upon receipt and retransmission, and these timestamps are forwarded to a network management system for delay apportionment analysis, using either an International Mobile Subscriber Identity (IMSI) or a probe bit in the message header to identify probe sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive logging of timestamps across multiple network elements is performed to measure round trip delay, then measurement precision is improved, but device complexity and processing overhead increase significantly
Solution Approach 1:
The patent segments the network monitoring function by introducing probe session indicators that are inserted at the source and followed through network elements. Each network element only needs to log timestamps for packets containing its assigned probe session indicator, rather than all packets. This segmentation of the monitoring task across different network elements reduces individual device complexity while maintaining overall measurement precision.
Solution Approach 2:
The probe session indicator acts as an intermediary mechanism that enables selective timestamp logging. Instead of requiring complex coordination between all network elements to monitor all traffic, the indicator serves as a simple marker that intermediates the monitoring process, allowing each element to independently identify and log only relevant probe packets without increasing overall system complexity.
2Measurement precision
If timestamps are logged for all packets to ensure accurate delay measurement, then measurement precision is improved, but productivity and processing efficiency deteriorate due to CPU-intensive operations
Solution Approach 1:
The patent applies local quality by making timestamp logging selective rather than universal. Each network element logs timestamps only for packets containing its specific probe session indicator, not for all passing traffic. This localized approach maintains measurement precision for probe sessions while significantly improving processing efficiency by avoiding unnecessary logging operations on regular traffic.
Solution Approach 2:
Instead of performing the excessive action of logging all packets, the patent applies partial action by logging only the subset of packets that contain probe session indicators. This partial logging approach provides sufficient data for accurate delay measurement of probe sessions without the CPU overhead of processing and logging every packet in the network.
3Measurement precision
If network protocol analyzers decode captured packets to associate timestamps with specific users and services, then measurement precision is improved, but device complexity increases and encrypted packets cannot be processed
Solution Approach 1:
The patent applies preliminary action by inserting the probe session indicator into packets at the source before they traverse the network. This pre-marking eliminates the need for network protocol analyzers to decode and analyze packet contents to identify user sessions. The indicator is already in place, allowing simple matching at each network element without complex decoding operations, and this works regardless of packet encryption since the indicator is part of the packet structure itself.
Data Source
AI summary
A method and apparatus for Round Trip Delay KPI Monitoring in a live network using a user plane probe session is disclosed for measuring round trip delays in a manner that allows latency to be apportioned to network elements. The method and apparatus for Round Trip Delay KPI Monitoring in a live network using a user plane probe session includes transmitting a loopback packet containing a probe session indicator and capturing timestamps of arrival and departure times at each network element traversed by the loopback packet, and then transmitting the timestamps to a Network Management System.