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[SRX] Why secondary node of SRX cluster is not synchronizing with NTP server (for JUNOS prior 12.1X47)

  [KB21725] Show Article Properties


Summary:

This article explains why the current time on secondary node of the branch-SRX cluster is not synchronized with the NTP server. It also proposes a workaround for this issue.

Notes:

  • This article applies to branch SRX platforms only.
  • The information on this KB article is applied to SRX running Junos releases prior to version 12.1X47.
  • Starting from Junos release 12.1X47-D10, NTP synchronization will happen between active RE and backup RE, Packet Forwarding Engines.  Rrefer to following documentation for detail: NTP Time Synchronization on Chassis Cluster
Symptoms:

On a branch SRX cluster with NTP server configured, one may notice that only the node that is currently primary for redundancy-group 0 (RG0) is actually synchronizing with the NTP. The current time on the second node may be incorrect.

Cause:

This is an expected behavior, because by design, the NTP daemon does not run on the backup routing engine  (RE) - that is, on the RE that is secondary for RG0.

Note: This applies to branch SRX platforms only.

Solution:

Upon RG0 failover, the formerly secondary RE will become the primary. As a result, an NTP daemon will be started and the time will be synchronized automatically.

However, in some cases this solution is not enough. For example, the log files written by the secondary node may have incorrect timestamp, making troubleshooting difficult. The time can be manually synchronized for both nodes with the following CLI command:

set date ntp

The IP address of the desired NTP server can be specified. When omitted, the currently configured NTP server will be used.

This command will run on both nodes of the cluster, as can be seen from the following output:

{primary:node1}
root@LU2> set date ntp 172.17.28.5
node0:
--------------------------------------------------------------------------
27 Sep 15:01:53 ntpdate[1256]: step time server 172.17.28.5 offset -30514.972815 sec

node1:
--------------------------------------------------------------------------
27 Sep 15:01:53 ntpdate[1484]: step time server 172.17.28.5 offset -30010.597032 sec

 

In order to keep the time synchronized, periodically run this command automatically, but configure an event-options policy.

Please refer to the following KB article for more details: KB22795 - [SRX] How to schedule operational commands without using scripts


Note: since the NTP server has to be reachable from the backup RE, you have to use fxp0 interfaces and, in most cases, configure backup-router statement.
Modification History:
2019-05-06: Update KB to indicate this KB applies to Junos releases  prior to 12.1X47.
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