You want to convert an MX Series router from a VXLAN Layer 2 gateway to a VXLAN Layer 3 gateway for VNI 100. You have already configured an IRB…

To convert a VXLAN Layer 2 gateway to a Layer 3 gateway, you must enable routing for the VNI. This is achieved by associating an Integrated Routing and Bridging (IRB) interface with the bridge domain that corresponds to the VNI. The command set bridge-domains routing-interface irb. performs this association. This configuration links the Layer 2 forwarding domain (the bridge-domain) to a Layer 3 routing interface (the IRB), allowing the router to perform routing for traffic arriving in that VNI.

A. This command enables ISIS on the IRB interface. While the IRB may participate in a routing protocol, this command does not create the essential link between the L2 bridge-domain and the L3 interface.

B. This command uses the vlans stanza. While functionally similar, modern EVPN-VXLAN configurations on MX Series typically use the bridge-domains stanza for service-provider style configurations.

D. This command enables OSPF on the IRB interface. This is for exchanging routing information with other routers, not for enabling the L3 gateway function for the VNI itself.

1. Juniper Networks Documentation. (2023). Configuring a VXLAN Layer 3 Gateway. Junos OS, Feature Guides. See the section "Configuring a VXLAN Layer 3 Gateway," Step 5.

2. Juniper Networks Documentation. (2023). Example: Configuring a Centrally-Routed Bridging Overlay. Junos OS, Feature Guides. This example shows the use of set bridge-domains VLAN-100 routing-interface irb.100.

3. Juniper Networks Documentation. (2023). routing-interface (Bridge Domain). Junos OS, Routing Protocols and Policies Command Reference.