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[SRX/EX] Troubleshooting a SRX chassis cluster that is connected via a layer 2 switch



Article ID: KB25017 KB Last Updated: 24 Jul 2020Version: 5.0

This article provides information on how to troubleshoot a clustering issue, when running over a L2 switch.  It also is a jumpstation to other useful KB links on this topic.

KEY words for searching/indexing purpose:

SRX cluster, L2 switch, layer2 switch, SRX HA, SRX switch, SRX clustering
How to troubleshoot a clustering issue, when running over a L2 switch
First, when clustering over a L2 switch, you do not have to implement any extra configuration/settings on the SRX device; as compared to clustering with a back-to-back connection. If removing the switch resolves the issue, then the issue is with the switch.

Procedure on the switch:

As the SRX is using a Juniper proprietary protocol for HA communication, confirm the following parameters:
  1. Interfaces for the cluster on the switch should have the maximum MTU configured, which for all platforms is 9014; with the exception of SRX100, which requires a MTU of 1632.

  2. The switch is not performing IP legitimate check.

  3. IGMP snooping is disabled.

Procedure on the SRX device:

Confirm if VLAN tagging is enabled or disabled on the chassis cluster control port.

From Junos 10.2R3 onwards, VLAN tagging is not enabled, by default, on the control port. To check the control port tagging status, execute the show chassis cluster information detail command and look for Control port tagging in the output.

Useful KB articles:
Modification History:
2020-07-24: Fixed broken link.
2020-03-24: minor non-technical edits.
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