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Known Behavior for QFX5110 and QFX5200 Switches


This section lists known behavior, system maximums, and limitations in hardware and software in Junos OS Releases 15.1X53 for QFX5110 and QFX5200 switches.

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

Interfaces and Chassis

  • The issue occurs when running LACP between Juniper Networks and vendor devices with different timers (Juniper Networks fast and vendor slow) on both sides. On the vendor side it takes almost 90 seconds to bring the interface down from the bundle. When one interface is removed from the LAG on the Juniper side, the lead on the vendor side needs to time out to bring the interface down from the bundle. This results in unexpected outage behavior on the network. PR1169358

  • On a QFX5110 switch configured with a LAG created with two interfaces—such as et-0/0/1, speed 40 Gbps and et-0/0/2, speed 40 Gbps—and if one of the interfaces is dynamically hot-swapped with a 100-Gbps interface, then no error message is displayed. However, when you create a mixed-speed configuration from the start with the CLI, the behavior is as expected and appropriate error messages are displayed. As a workaround, if you dynamically hot-swap a LAG member interface for one with a different speed, delete the LAG interface and re-configure it. PR1204545

  • On a QFX5110-48S switch, a Gigabit Ethernet interface goes down and comes back up on a peer after a reboot. PR1237572

  • In certain cases the link state might stay as UP between a QFX5200 switch and different NICs (third-party devices) for different combinations of FEC on and off. If the link is taken down from the third-party device end when there is an FEC mismatch, as a workaround, use the CLI command to enable or disable FEC on the QFX5200 to match the FEC mode on the third-party device. PR1246654

  • On QFX5110, 100m speed is supported only on Juniper SFP-T transceivers. PR1358430

Layer 2 Features

  • The number of samples expected which is based on the actual traffic-rate and configured sample-rate might not match with the actual number of samples that the sflow agent sends to the collector. PR1381378

Layer 3 Features

  • On a QFX5110 switch with a filter-based forwarding (FBF) configuration, Layer 3 forwarding might stop working if the ARP entry for the destination host address is deleted on the switch. FBF is used to derive the routing instance for this host address. As a workaround, configure static ARP entries for host addresses where FBF is needed. PR1200707


  • On QFX5200 switches, if you apply either an 802.1p rewrite rule or a DSCP rewrite rule on a network interface that has a Layer 2 circuit that is configured but not yet up, the rewrite rule does not work. If you apply the rewrite rule after the Layer 2 circuit is up, the rewrite rules are applied and work correctly. PR1105354

Multicast Protocols

  • The set protocols l2-learning disable-vxlan-multicast-transit vxlan-multicast-group multicast-group command should not be configured on a PIM RP router for QFX5110 or QFX5200 because it impacts Layer 3 multicast protocol behavior. PR1268167