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Known Behavior


This section lists known behavior, system maximums, and limitations in hardware and software in Junos OS Release 17.4R2 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

  • During a nonstop software upgrade (NSSU) on an EX4300 Virtual Chassis, a traffic loop or loss might occur if the Junos OS software version that you are upgrading and the Junos OS software version that you are upgrading to use different internal message formats. PR1123764


  • The issue is specific to a downgrade(17.4T) and a core is seen only once during the downgrade because of a timing issue in the sdk toolkit upgradation, after which dcpfe recovers on its own and no issues are seen after that. PR1337008

Interfaces and Chassis

  • Configuring link aggregation group (LAG) hashing with the [edit forwarding-options enhanced-hash-key] inet vlan-id statement uses the VLAN ID in the hashing algorithm calculation. On some switching platforms, when this option is configured for a LAG that spans FPCs, such as in a Virtual Chassis or Virtual Chassis Fabric (VCF), packets are dropped due to an issue with using an incorrect VLAN ID in the hashing algorithm. As a result, the vlan-id hashing option is not supported in a Virtual Chassis or VCF containing any of the following members: EX4300, EX4600, QFX3500, QFX3600, QFX5100, or QFX5110 switches. Under these conditions, use any of the other supported enhanced-hash-key hashing configuration options instead. PR1293920

Platform and Infrastructure

  • On EX4300 and EX4600 switches, if a remote analyzer has an output IP address that is reachable through a route learned by BGP, the analyzer might be in a down state. PR1007963

  • On an EX4300 Virtual Chassis, when you perform an NSSU, there might be more than five seconds of traffic loss for multicast traffic. PR1125155

  • On EX4300 switches, when 802.1X single-supplicant authentication is initiated, multiple "EAP Request Id Frame Sent" packets might be sent. PR1163966

  • On EX4300 10G links, preexisting MACsec sessions might not come up after the following events: Process (pfex, dot1x) restart or system restart link flaps PR1294526

  • mcsnoopd might crash when all the core facing interfaces that are part of the L2 domain have flapped and it is attempting to flood a packet received over a CE interface, over the core-facing interfaces. PR1329694

Virtual Chassis