Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Known Limitations

Learn about known limitations in Junos OS Release 21.4R1 for QFX Series switches.

For the most complete and latest information about known Junos OS defects, use the Juniper Networks online Junos Problem Report Search application.

General Routing

  • On the QFX5000 line of switches with storm control, there is a significant difference between the configured rate and the actual rate. PR1526906

  • On the QFX5200 and QFX5100 line of switches, double-count packets gets forwarded over IP-IP tunnel that are egress-sampled. PR1555922

  • Unexpected multicast traffic streams after enabling EVPN. PR1570689

  • On the QFX5000 line of switches, the IRACL filters do not match the VXLAN tunnel terminated packets. PR1594319

  • The 1pps performance test fails on the copper ports. PR1618533

  • Junos OS does not support the unified ISSU on QFX5120-48Y line of switches if there is a change in the Cancun versions of the chipset SDKs between the releases. A change in the Cancun firmware leads to the chip reset impacting ISSU. The Cancun versions in the chipset SDKs must be the same between two Junos OS releases for ISSU to work. PR1634695


  • Software image upgrade from Junos OS Release 21.1 (or earlier) to Junos OS Release 21.2 (or later) requires no-validate command as a mandatory action. PR1586481

High Availability

  • Starting in Junos OS Release 21.4R1, QFX5120-48Y switches support unified in-service software upgrade (ISSU). However, QFX5120-48Y switches provide unified ISSU support only if the Cancun versions in the chipset SDK are the same in the current version and the version you are upgrading to. PR1634695