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Junos OS Release Notes for EX Series Switches


These release notes accompany Junos OS Release 16.2R2 for the EX Series. They describe new and changed features, limitations, and known and resolved problems in the hardware and software.

You can also find these release notes on the Juniper Networks Junos OS Documentation webpage, located at

New and Changed Features

This section describes the new features and enhancements to existing features in the Junos OS main release and the maintenance releases for EX Series.


The following EX Series switches are supported in Release 16.2R2: EX9200.

Release 16.2R2 New and Changed Features

There are no new features or enhancements to existing features for EX Series in Junos OS Release 16.2R2.

Release 16.2R1 New and Changed Features

There are no new features or enhancements to existing features for EX Series in Junos OS Release 16.2R1.

Changes in Behavior and Syntax

This section lists the changes in behavior of Junos OS features and changes in the syntax of Junos OS statements and commands from Junos OS Release 16.2 for the EX Series.

General Routing

  • Support for deletion of static routes when the BFD session goes down (EX Series)—Starting in Junos OS Release 16.2R2, the default behavior of the static route at the [edit routing-options static static-route bfd-admin-down] hierarchy level is active. So, the static routes are deleted when the BFD receives a session down message.


  • Support for status deprecated statement in YANG modules (EX9200)—Starting with Junos OS Release 16.2R1, Juniper Networks YANG modules include the status deprecated statement to indicate configuration statements, commands, and options that are deprecated.

User Interface and Configuration

  • Integers in configuration data in JSON format are displayed without quotation marks (EX Series)—Starting in Junos OS Release 16.2R2, integers in Junos OS configuration data emitted in JavaScript Object Notation (JSON) format are not enclosed in quotation marks. Prior to Junos OS Release 16.2R2, integers in JSON configuration data were treated as strings and enclosed in quotation marks.

  • Changes to the XML and JSON output when displaying the differences between the candidate and active configurations (EX Series)—Starting in Junos OS Release 16.2R2, when you compare the candidate and active configurations and display the differences in XML or JSON format, for example by using the show | compare | display (json | xml) CLI command or the <get-configuration compare="rollback" format="(json | xml)"> RPC, the device omits the <configuration> tag in the XML output and omits the configuration object in the JSON output if the comparison either returns no differences or if the comparison returns differences for only non-native configuration data, for example, configuration data associated with an OpenConfig data model.

Known Behavior

There are no known limitations for the EX Series switches in Junos OS Release 16.2.

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

Known Issues

This section lists the known issues in hardware and software in Junos OS Release 16.2R2 for the EX Series.

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

High Availability (HA) and Resiliency

  • On EX9200 Virtual Chassis, in a rare scenario, GRES might not reach the ready state and might fail to start, because the Routing Engine does not receive the state ack message from the Packet Forwarding Engine after performing GRES. This is a timing issue. It might also stop Routing Engine resource releasing and then cause resource exhausting. Reboot the system if this problem occurs. PR1236882

Network Management

  • SNMP queries to retrieve jnxRpmResSumPercentLost will return the RPM/TWAMP probe loss percentage as an integer value whereas the precise value (including decimal points) can be retrieved through the CLI by using the following commands:

    • show services rpm probe-results

    • show services rpm twamp client probe-results


Platform and Infrastructure

  • On EX9208 switches, a DCD restart might disable the member links in an MC-LAG, resulting in traffic loss. PR1229001

Port Security

  • On an EX9200-6QS line card, storm control might not work for multicast traffic. PR1191611

Resolved Issues

This section lists the issues fixed in the Junos OS main release and the maintenance releases for EX Series switches.

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

Resolved Issues: Release 16.2R2

Authentication and Access Control

  • On EX9200 Virtual Chassis, MAC address learning might fail on an authenticated interface assigned to voice-vlan by dynamic VLAN assignment in single-secure mode. PR1212826

  • On EX9200 switches, a MAC address corresponding to an authenticated session (dot1x) might age out as soon as traffic is not received from this MAC address for more than a few seconds (approximately 10 seconds). This leads to deletion of the authenticated session and a corresponding traffic loss. PR1233261

High Availability (HA) and Resiliency

  • On EX9200 switches, if ISSU is used to upgrade Junos, it is possible that an unnecessary thread will run on an FPC after the upgrade procedure. This thread can potentially enter into a loop and trigger a stop of forwarding traffic on that particular FPC. PR1249375

Interfaces and Chassis

  • On an EX9200 switch with MC-LAG, when the enhanced-convergence statement is enabled, and when the kernel sends a next-hop message to the Packet Forwarding Engine, the full Layer 2 header is not sent and a packet might be generated with an invalid source MAC address for some VLANs. PR1223662

Port Security

  • On EX9200 switches, after an ISSU is performed, storm control takes effect only after you delete the storm control configuration and then re-create it. PR1151346

  • A vulnerability in IPv6 processing has been discovered that may allow a specially crafted IPv6 Neighbor Discovery (ND) packet destined to an EX Series Ethernet Switches to cause a slow memory leak. A malicious network-based packet flood of these crafted IPv6 NDP packets may eventually lead to resource exhaustion and a denial of service. Use access lists or firewall filters to limit ICMPv6 traffic destined to the switch only from trusted hosts. PR1206593

  • On EX9200 switches, after a MACSec link flaps, traffic is not forwarded across the MACSec link. PR1269229

Routing Policy and Firewall Filters

  • On EX9200 switches, if a firewall filter that has action tcp-reset is applied to an IRB interface, action tcp-reset does not work properly. PR1219953

Routing Protocols

  • On EX9200 switches, in a rare condition after a BGP session flaps, BGP updates might not be sent completely, resulting in BGP routes being shown in the advertising-protocol table on the local end but not shown in the receive-protocol table on the remote end. PR1231707

Spanning-Tree Protocols

  • On EX9200 switches, if set protocols xstp interface all edge is configured in combination with set protocols xstp bpdu-block-on-edge, interfaces do not go down (Disabled - Bpdu-Inconsistent) when they receive BPDUs; they transition to non-edge. If an interface is configured specifically with set protocols xstp interface interface-name edge, then when that interface receives a BPDU, it goes down or transitions into Disabled - Bpdu-Inconsistent correctly. As a workaround, configure set protocols layer2-control bpdu-block interface all. PR1210678

  • On EX9200, the command set protocols rstp interface all edge configures all interfaces to go into BPDU block even if an interface is explicitly disabled under the rstp hierarchy. PR1266035


  • If an EX9200 switch is configured as a PE router connected to a multihomed site in an EVPN/MPLS network, RPD core files might be created on the EX9200 when more than 255 logical interfaces from the same physical interface/ESI are added to the virtual switch instance configuration. Then some logical interfaces are removed from the ESI (that is, rollback of the configuration). PR1251473

Documentation Updates

There are no errata or changes in Junos OS Release 16.2R2 for the EX Series switches documentation.

Migration, Upgrade, and Downgrade Instructions

This section contains the upgrade and downgrade support policy for Junos OS for the EX Series. Upgrading or downgrading Junos OS can take several hours, depending on the size and configuration of the network. For information about software installation and upgrade, see the Installation and Upgrade Guide.

Upgrade and Downgrade Support Policy for Junos OS Releases

Support for upgrades and downgrades that span more than three Junos OS releases at a time is not provided, except for releases that are designated as Extended End-of-Life (EEOL) releases. EEOL releases provide direct upgrade and downgrade paths—you can upgrade directly from one EEOL release to the next EEOL release, even though EEOL releases generally occur in increments beyond three releases.

You can upgrade or downgrade to the EEOL release that occurs directly before or after the currently installed EEOL release, or to two EEOL releases before or after. For example, Junos OS Releases 10.0, 10.4, and 11.4 are EEOL releases. You can upgrade from Junos OS Release 10.0 to Release 10.4 or even from Junos OS Release 10.0 to Release 11.4. However, you cannot upgrade directly from a non-EEOL release that is more than three releases ahead or behind. For example, you cannot directly upgrade from Junos OS Release 10.3 (a non-EEOL release) to Junos OS Release 11.4 or directly downgrade from Junos OS Release 11.4 to Junos OS Release 10.3.

To upgrade or downgrade from a non-EEOL release to a release more than three releases earlier or later, first upgrade to the next EEOL release and then upgrade or downgrade from that EEOL release to your target release.

For more information about EEOL releases and to review a list of EEOL releases, see

Product Compatibility

Hardware Compatibility

To obtain information about the components that are supported on the devices, and the special compatibility guidelines with the release, see the Hardware Guide for the product.

To determine the features supported on EX Series switches in this release, use the Juniper Networks Feature Explorer, a Web-based application that helps you to explore and compare Junos OS feature information to find the right software release and hardware platform for your network. Find Feature Explorer at

Hardware Compatibility Tool

For a hardware compatibility matrix for optical interfaces and transceivers supported across all platforms, see the Hardware Compatibility tool.