We are currently running JunOS 23.4R2-S4.11 flex on a QFX5200-32C-32Q Virtual Chassis.
Prior to the upgrade, we experienced intermittent connectivity issues affecting random customer hosts across multiple VLANs. The affected hosts could reach their default gateway, but could not access external networks. The issue was only resolved by clearing ARP on the entire IRB interface, while clearing ARP for an individual host did not restore connectivity.
After upgrading from JunOS 23.2R1-S2.5 flex to JunOS 23.4R2-S4.11 flex and performing a full Virtual Chassis reboot, the original issue appears to have been significantly reduced.
However, we recently observed an isolated case where a host had:
- a valid ARP entry,
- a valid MAC entry,
- a valid forwarding-table entry,
- successful connectivity to the default gateway,
but was unable to reach external destinations.
In this case, connectivity was immediately restored by executing:
clear arp interface irb.xxx
We would like to understand whether this behavior is related to a known ARP/neighbor adjacency issue, host-route programming in the PFE, or any known software defect affecting QFX5200 platforms.
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Eugeniu Croitorov
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