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Spirent TestCenter: How to sync multiple remote chassis? What are the External Time Reference (ETR) methods available?

Supported Spirent TestCenter Chassis and Appliances​
  • C1
  • C50
  • C100
  • N11U
  • N4U
Supported ETR devices
  • HP58503 for GPS HP-58503
  • HP59551 for GPS HP-59551
  • ZYFER for GPS Zyfer NanoSync
  • XLI for GPS XLI Symmetricom
  • TP5000 for GPS TP5000 Symmetricom
  • ENDRUN for CDMA Praecis Endrun Technologies
  • PTP for Conemtech IEEE1588/PTPV2
  • DEFAULT for all except TP5000 
The above list has obsolete products but should still work although we do not guarantee obsolete/no longer manufactured products.
  • Starting with 5.01, NMEA 0183 is supported. 
    • Calnex ETR is the only recommended and qualified unit (but other compliant NMEA units should work.)
    • The device in use must be configured to 9600 baud rate and periodically generate a RMC message in order to work with a Spirent TestCenter chassis.
  • Release Note for v5.01
  • There are 3 external time reference methods to sync up chassis in different locations.
    • There are 3 connections on the chassis for a GPS connection.
    • Connect the serial port, 10Mhz coax, 1pps coax to the GPS unit 
    • The chassis will automatically change from internal sync to GPS if the GPS device is ready
    • Below is the setup information for the Calnex/NMEA GPS device with screen shots. 
      • There are hundreds of GPS devices available on the market that support the NMEA0183 standard.
      • However its not feasible to test and validate all devices. As so we have tested and validated the Calnex Option 132 Rb/GPS Frequency Reference device without chassis.
      • With the Calnex device the user should connect a GPS antenna, 1PPS, 10MHz and Serial/RS232 communication as illustrated:
      • For devices other than the Calnex Option 132, the user should reference the device manual to configure the RS232 to use a 9600 baud rate and output RMC messages.
      • Once the Calnex device is connected to the GPS antenna, it requires 24 hours for it to lock onto the satellites (per Calnex spec). Lock status can be visually validated by observing the Track/Sync LED on the front panel of the Calnex device.
      • Configuring the Spirent Chassis to use this Calnex device as the source can be done from the admin menu:
        • Type: "etr device NMEA" to select NMEA GPS source.
      • Once the chassis has synchronized to the Calnex GPS device, the user will the Clock Source change to "GPS" from the STC GUI:
  2. NTP
    • This timing comes from the network.
    • The chassis admin port will be used as a client and you will need to add NTP server IP addresses from the console.
    • Attached documentation may help (001786C_NTP_Operation.pdf)
    • How to configure NTP on a chassis? The snap shot below has a ntp command for you to enable the ntp client as well as add ntp servers
      • One important note is to make sure no other external time references are configured. (disable PTP, remove any chassis sync cables, remove any GPS connections)
      • Note there was a change in v5.00 and above on what is displayed when using any NTP client/server status/summary commands.
        • v4.99 and below view
        • v5.00 and above now shows:​
      • The old method allowed multiple servers to be entered and NTP would sync to the best server.
      • The new method only allows a single IP address.
        • another way around using multiple IP addresses is to use an NTP pool which uses a single IP address
        • Example: is an IP address to a pool of servers. ( -
        • actually, to be more precise, the new format can still add multiple servers but it will only use the last one entered.
          • Here is some behavior with the new format
            • You can't see the list of entered servers
            • Only the last entered server can be seen and used.
            • If NTP client already enabled when adding a new server, need to disable/enable NTP client
          • As you can tell this basically is saying only one IP address should be used for the new method.
        • For troubleshooting NTP
          • The old method would show which server is better and if the sync was with that server.
          • The new method doesn't show this information but now that STC application has an NTP Client emulation feature, you could use that to check connectivity with the NTP server.
        • ​​
  3. 1588v2 PTP
    • There is a separate 1588v2 port which you can use to connect directly to a 1588v2 PTP master or connect it to the network
      • This port only supports a speed of 100M (currently hardware limitation)
    • The master sends its time information which the chassis will receive
    • The chassis is always a slave and will send Delay request messages in which the master would respond with Delay response messages
    • Currently we have had some stability issues with 1588 which was just fixed in v4.75 that is being release next week.
    • There is no documentation on 1588v2 external time reference.
    • The snap shot below has a ptp command for you to set the IP address that the chassis slave will use when sending out the Delay request messages.
  • Note that in all cases, the chassis will only sync to its respective time source when test ports are shown as available.
  • If someone has a test port reserved, the chassis will not switch to the external time reference.
Attachment Description
Spirent TestCenter NTP Operation App Note 5

Product : Spirent TestCenter,Chassis