EVPN/VXLAN collapsed core configured on QFX5200 and EX4300 not working.

VXLAN constrains and considerations on QFX5200 and ex4300:

• QFX5120-48Y, QFX5120-32C, and QFX5200 switches support hierarchical equal-cost multipath (ECMP), which allows these switches to perform a two-level route resolution. However, all other QFX5xxx switches do not support hierarchical ECMP. As a result, when an EVPN Type-5 packet is encapsulated with a VXLAN header, then de-encapsulated by a QFX5xxx switch that does not support hierarchical ECMP, the switch is unable to resolve the two-levels of routes that were in the inner packet. The switch then drops the packet.

• (QFX5100, QFX5110, QFX5120, QFX5200, and QFX5210 switches) When you configure the IRB interfaces on a device that is concurrently supporting configured VLANs on both a centrally-routed bridging overlay and an edge-routed bridging overlay, the IRB MAC address and virtual gateway MAC address on the IRB interface for the centrally-routed bridging overlay must be different from the IRB MAC address and virtual gateway MAC address on the IRB interface for the edge-routed bridging overlay.

• (QFX5xxx and EX46xx switches) don't support configuring and using MPLS and EVPN-VXLAN at the same time on the same device. We have this constraint because Broadcom-based platforms use the same hardware tables to store tunnel and virtual port information used by both the MPLS and VXLAN feature sets. Also, you can't use an MPLS underlay with EVPN and a VXLAN overlay; this is a Broadcom hardware limitation.

• (QFX5xxx and EX46xx switches) We don’t support tagged L3 interfaces and L2 bridge domains as subunits of the same interface with an IRB in service provider style configurations.

• EVPN-VXLAN on an EX4300-48MP Virtual Chassis only in campus networks.

• (EX4300-48MP switches only) The following styles of interface configuration are not supported:

• Service provider style, where a physical interface is divided into multiple logical interfaces, each of which is dedicated to a particular customer VLAN. The extended-vlan-bridge encapsulation type is configured on the physical interface.
• Flexible Ethernet services, which is an encapsulation type that enables a physical interface to support both service provider and enterprise styles of interface configuration.

• For more information about these styles of interface configuration, see Flexible Ethernet Services Encapsulation.

https://www.juniper.net/documentation/us/en/software/junos/evpn/topics/concept/vxlan-constraints-qfx-series.html