PTP Configuration on an ESXi fails at "PTP_LISTENING" when PTP server is running in Unicast Mode.
Article ID: 428532
Updated On:
Products
Issue/Introduction
- PTP configuration on an ESXi fails with error "
Configuration is not working normally" when testing it.
(In the vSphere Client, navigate to Hosts and Clusters and select your ESXi host.
Configure > System > Time Configuration > Test Services > Time Synchronization Services test)
- Running the ptp test command below shows "
Port State indicates time is not in sync: PTP_LISTENING"
# esxcli system ptp test
Comments: Service analysis started on host: ####.####.####.### Test started at: yyyy-mm-yyThh:mm:ZZZ Time Service is administratively enabled. Virtual NIC vmk# : Admin: Up IP Interface: vmk# IPv4 Address: STATIC x.x.x.x IP Interface: vmk# connected to x.x.x.x-x_xx_xxx_xx on vSwitchX IP Network Stack: defaultTcpipStack Physical NIC vmnic# : Admin: Up Oper: Up Physical NIC vmnic# : Admin: Up Oper: Up Firewall Rule: ptpd allows traffic on port: 319 Firewall Rule: ptpd allows only user-specified IPs IPv4: x.x.x.x ptpd is running PID: ###### Port State indicates time is not in sync: PTP_LISTENING Kernel clock type: ptp Announce received 0 Clock Source ptp Delay mechanism E2E DelayReq sent 0 DelayResp received 0 Follow-up received 0 Interface vmk# Performance Message RX 0/s TX 0/s Pin Count 0 Port state PTP_LISTENING Sync received 0 Service analysis completed.
- The
/var/run/log/syslog.logshows the PTP daemon repeatedly restarting its transports due to a failure to transition out of the LISTENING state:
```2026-01-26T02:09:24.869Z Wa(28) ptpd[######]: Still in LISTENING after 5 restarts - restarting transports2026-01-26T02:10:26.308Z Wa(28) ptpd[######]: Still in LISTENING after 5 restarts - restarting transports2026-01-26T02:11:27.748Z Wa(28) ptpd[######]: Still in LISTENING after 5 restarts - restarting transports
```
- When you run packet capture command on VMK (configured for PTP) , you wouldn't notice any packet showing any communication with PTP server's IP.
# pktcap-uw --vmk vmk<No:> --dir 2 --ip <IP of PTP server> --udpport 319 -o - | tcpdump-uw -enr - - The PTP Server is running in the Unicast Mode.
- The
/etc/ptp.conffile shows the current PTP configuration(Multicast) of ESXi host-
Do not edit this file, config store overwrites it
global:statistics_update_interval=10 global:use_syslog=true global:log_status=y global:statistics_file=/var/run/log/ptpd.stats global:statistics_file_max_size=10240 global:statistics_file_max_files=9 ptpengine:domain=0 ptpengine:preset=slaveonly ptpengine:ip_mode=multicast ptpengine:use_libpcap=n ptpengine:sync_outlier_filter_enable=y ptpengine:delay_outlier_filter_enable=y ptpengine:ip_dscp=46 ptpengine:calibration_delay=5 clock:drift_handling=file clock:drift_file=/etc/ptp.drift
- The
/var/run/log/ptpd.statson the ESXi host also indicate that PTP Client did not receive any packets from the Master.
# Timestamp, State, Clock ID, One Way Delay, Offset From Master, Slave to Master, Master to Slave, Observed Drift, Last packet Received, Sequence ID, One Way Delay Mean, One Way Delay Std Dev, Offset From Master Mean, Offset From Master Std Dev, Observed Drift Mean, Observed Drift Std Dev, raw delayMS, raw delaySM 2026-01-26 02:08:23.427860, init, 2026-01-26 02:08:23.461833, lstn_init, 1 2026-01-26 02:08:35.749711, lstn_init, 1 2026-01-26 02:08:48.037594, lstn_init, 1 2026-01-26 02:09:00.325477, lstn_init, 1 2026-01-26 02:09:12.613361, lstn_init, 1 2026-01-26 02:09:24.869307, flt, 2026-01-26 02:09:24.869338, flt, 2026-01-26 02:09:24.869359, init, ... <snip>
Environment
NSX 4.x and above
Cause
- The PTP server is currently operating in Unicast Mode, while ESXi hosts strictly require Multicast Mode for PTP support.
- PTP synchronization fails due to this configuration mismatch
Resolution
As ESXi hosts support PTP configuration in Multicast Mode only , the recommendation is to configure the PTP server aswell in Multicast Mode.
Additional Information
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