Challenges with linuxptp on Telco RAN deployments

Abstract

Challenges with ptp4l on Telco RAN deployments.Linuxptp project is the most commonly adopted software implementation of the IEEE 1588 protocol on Linux-based systems.This paper identifies existing challenges and gaps in the current implementation of the linuxptp software stack. It is important to address these challenges to adapt to 4G/LTE and 5G/NR Telco RAN deployments. These findings result from the collaboration of Altiostar and Intel on IEEE 1588-based ptp4l implementations in O-RAN systems with a COTS NIC card.The most important challenges outlined in the paper include:•Lack of support for dynamic configuration in ptp4l•Lack of support for system-level management•Ptp4l sync state machine is not fully compliant to ITU-T G.8275.1/G.8275.2 standards•Link Aggregation(LAG)/Aggregation Ethernet(AE) Support•Non-compliance to ITU-T G.8265.1 standard•Required support for ITU-T G.8273.4(APTS/PTS) for resiliency or redundancy•Non-compliance to O-RAN.WG4.CONF.0.v2.00 O-RAN Fronthaul Working Group Conformance Test Specification•Missing SyncE and ESMC support•Missing support for multiple time domains•Multiple follower/slave portsThe paper shows how these challenges make industry applications much more complex, if not impossible. It may also lead to creation and implementation of non-standard solutions. Not addressing these gaps may lead to non-compliance with timing specs (ITUT/O-RAN), impacting the adoption rate of linuxptp in the RAN.