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Troubleshooting Reader/Gateway Network Time Protocol (NTP) configurations




Network Time Protocol (NTP) is used to get readers and gateways to sync their clocks. The purpose of this article is to discuss techniques for troubleshooting and resolving NTP issues that prevent our readers and gateways from synchronizing their clocks.  Each one of the troubleshooting steps mentioned are grouped into their appropriate section and can be done individually.  Here are the most common NTP problems we've encountered:
        - NTP is mis-configured on the reader,
        - NTP servers are not available, 
        - NTP network ports are blocked by firewalls,
        - NTP servers are mis-configured.

Here are a few good places to read more about NTP: 
       - https://en.wikipedia.org/wiki/Network_Time_Protocol
RShell Reference Manual located here: https://support.impinj.com/hc/en-us/articles/202755298-Reader-Documentation


Table of Contents



1. Upgrade to our Latest Octane Firmware

A number of improvements and NTP issues have been fixed as of Octane Firmware version

Please upgrade your Octane Firmware to the latest version to make sure this is not an issue that has already been resolved.


2. Disable Dynamic Servers

When the reader or gateway is configured for DHCP, the default behavior is to use the dynamic NTP servers (Dynamic Servers) that are configured as part of the DHCP server.  We have run into situations where the servers added to our readers via DHCP cause clock synchronization issues with other systems.   In order to get around these issues the NTP dynamic servers feature needs to be disabled and static NTP servers added.  To accomplish this, please ssh into the reader/gateway, disable dynamic servers, and add static NTP servers by issuing the following RShell commands:

   config network ntp disable
   config network ntp dynamicservers disable
   config network ntp add <static NTP server hostname/IP Address>
   config network ntp add <static NTP server hostname/IP Address>
   config network ntp enable


       Why we need to Enable and Disable NTP

In order to make any changes to the NTP settings on our readers and gateways, the following RShell command must be executed first:

    config network ntp disable

Failure to do so will yield the following error:

    Status ‘8, Permission Denied

Once all configuration changes are complete, please make sure to enable NTP again by issuing the following RShell command:

    config network ntp enable

Finally, please wait upto five (5) minutes before checking whether the NTP setup is now synchronized.


3. Check the Reader Logs

There are times where NTP is not functioning because the reader cannot reach the server.  The device logs can help you determine the type of NTP issue you're encountering.  To view them, issue the following RShell commands:

   show logging events err 1000
   show logging events app 1000

Here's an example of an NTP error you may see in the logs:


4. Verify the DNS and DHCP settings

If the settings for DNS, DHCP, and/or static settings are not correct, the reader/gateway will be unable to communicate with the NTP Server. 

Please verify all settings are valid by checking the following values:

    - IP Address
    - Gateway Address
    - Broadcast Address
    - IP Subnet Mask
    - NtpServerStaticAddress
    - DNS servers

The following commands can help determine how the reader is setup:

   show network summary
   show network dns
   show network ntp

Here is an example of a working synchronized ntp connection:

Here is an example output showing NTP not working: 

Most of the fields above should make sense but there are a few that need additional information.


Describes the state of the associated NTP Server and can have one of the following values:

  • Synchronized
  • Polled
  • SymmetricActive
  • SymmetricPassive
  • ReceivingBroadcast
  • SendingBroadcast

Stratum provides a mechanism for identifying how accurate of a time the NTP Server delivering time is relative to those servers acting as a reference clock and preventing timing loops where NTP servers are getting a time from another server that is getting its time from it. Stratum 0 devices are the most accurate non-network connected device (used as a reference clock). Stratum 1 devices are the most accurate ntp time that is accessible via a network connection and normally synchronizes with a Stratum 0 reference clock. Stratum 2 synchronize with Stratum 1 devices. Stratum 3 synchronize with Stratum 2 devices. Etc...


The value displayed in column reach is octal, and it represents the status of the reachability register. One digit in the range of 0 to 7 represents three bits. The initial value of that register is 0, and after every poll that register is shifted left by one position. If the corresponding time source sent a valid response, the rightmost bit is set.

During a normal startup the registers values are these: 0, 1, 3, 7, 17, 37, 77, 177, 377



5. Hardcode NTP Server Settings

Firewall and/or other network issues may require that you use your own internal NTP server, and manually point your reader there. An example of this setup can be found in the "Clock Synchronization and NTP Configuration" section of the ItemSense Installation Page:


Then setup the readers to communicate with this NTP Server with the following commands:

    config network ntp disable

    show network ntp
       - This will show what settings you currently have before you make changes.

    config network ntp dynamicservers disable

    config network ntp delall

    config network ntp add xxx.xxx.xxx.xxx
       - Replace "xxx.xxx.xxx.xxx" with the name of the new NTP Server

    config network ntp enable


6. Reboot the Reader/Gateway

Try rebooting the reader/gateway to see if the settings get corrected.


7. Contact Impinj Support

If all of the above changes fail to work, please contact Impinj Support (support@impinj.com) and provide the following information:

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Impinj (NASDAQ: PI) wirelessly connects billions of everyday items such as apparel, medical supplies, and automobile parts to consumer and business applications such as inventory management, patient safety, and asset tracking. The Impinj platform uses RAIN RFID, delivering information about items to the digital world and enabling the Internet of Things.