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Known Limitations

Learn about known limitations in this release for EX Series switches.

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


  • After a reboot during recovery process, the ESI LAGs come up before the BGP sessions, and routes or ARP entries are not synchronized. PR1487112

General Routing

  • When the device is up and running for a long time, there is a possibility FS gets bad blocks and it is accumulated. When any change done to it, it reloads and tries to recover the bad blocks from the FS. PR910445

  • Junos OS can hang trying to acquire the SMP IPI lock while rebooting when it is running as a VM on Linux and QEMU hypervisor. PR1385970

  • On all platforms running Junos OS, in a Q-in-Q environment, if xSTP is enabled on an interface that has a logical interface with vlan-id-list configured, then, it will only run on those logical interfaces whose vlan-id range includes native-vlan-id configured. All other xSTP will be in discarding state. This might lead to traffic drop. PR1532992

  • Whenever a firewall is configured with action inline monitoring and to count, the corresponding firewall counters will not show any increment in traffic statistics. This limitation is from underlying hardware. PR1542192

  • Inline monitoring security service might not report a IPv4 security violation when traffic is received with source IP address same as destination IP address. This is limitation from Hardware. PR1542213

  • On a virtual chassis, the CLI command to add license is not available on the backup member. Licenses must be added from the master member only. PR1545075

  • When user issues request support information to collect debug data for sharing with tech support, commands which are not supported for the platform will display a syntax error message. PR1547835

  • In a Virtual Chassis environment, whenever there is a Link Aggregation Group (LAG) configured with child members from different virtual chassis members, then layer2-header hashing should be used to distribute traffic across the LAG members. Usage of vlan-id based hashing is not recommended and might result in reduced throughput of the LAG. PR1548859

  • Tail drop is seen in WRED configuration statistics. PR1549910

  • Inline-monitoring service supports only upto a maximum of 8 instances. PR1550014

  • VRRP delegate-processing currently not supported on EX4400 series of switches. PR1552076

  • Packets mirrored through analyzer with ingress and egress interfaces across different virtual chassis members might have a different vlan-id from that of vlan-id of the exiting egress interface. This limitation is from underling hardware. PR1552905

  • "Resource deadlock avoided" messages are observed during software add-on EX4400. No functionality impact seen. PR1557468

  • License keys should be installed using either operational command or configuration set commands. Same license key should not be added via both operational and set comands. PR1557980

Interfaces and Chassis

  • Support for low power idle mode (EX4400-48T, EX4400-48P, EX4400-24T, and EX4400-24P)—Starting in Junos OS Release 21.1R1, the 1-Gbps or 100-Mpbs port switches to low power idle (LPI) mode based on the following conditions:.

    • When a port operates at 1-Gbps speed and no traffic is either received or transmitted, then the port enters LPI mode. If the 1-Gbps port transfers unidirectional or bidirectional traffic, then the port will not enter LPI mode.
    • When a port operates at 100-Mbps speed, the port switches to LPI mode, based on the direction of the traffic. The show interfaces interface-name extensive command displays RX LPI when there is no RX traffic and TX LPI when there is no TX traffic.

    You can view the interface that is in LPI mode by executing the show interfaces interface-name extensive command. The output field IEEE 802.3az Energy Efficient Ethernet displays the status of the LPI mode.

    [See show interfaces extensive .]


  • Software versions 21.1 and lower are running FreeBSD version 11 whereas from version 21.2 onward, the FreeBSD version is 12. Software upgrade to 21.2 (or later) from 21.1 (or earlier) will mandatorily need cli knob 'no-validate' to be used during software image upgrade process. (For EX4400 platforms, this is applicable from version 21.3 onward. Hence, for EX4400 platforms, software upgrade to 21.3 (or later) from 21.2 (or earlier) will mandatorily need cli knob 'no-validate' to be used during software image upgrade process.) PR1586481

User Interface and Configuration

  • Unsupported options can be seen under "restart" command. PR1545558

  • Python script is not supported in ZTP workflow. Python can run (during ZTP) only in few EX Series based flex images. PR1547557