JNCIE-ENT: EVPN and Services

This domain tests EVPN control-plane and VXLAN data-plane design: route types, VNI and route-target consistency, anycast gateways, and Ethernet segment multihoming. The exam expects you to explain why a MAC or prefix is or is not advertised.

Core rules

• EVPN uses BGP route types: Type 1 Ethernet auto-discovery, Type 2 MAC/IP advertisement, Type 3 inclusive multicast, Type 4 Ethernet segment, and Type 5 IP prefix. Type 2 carries host MAC/IP reachability; Type 3 builds BUM flooding; Type 5 supports IP-VRF prefix advertisement.
• VXLAN maps a VLAN or VRF to a VNI. The VTEP source is a reachable loopback: set switch-options vtep-source-interface lo0.0; enable protocols evpn encapsulation vxlan and include the VNI in extended-vni-list.
• Route targets control import/export between EVPN instances. A mismatch silently prevents route installation.
• Anycast gateway uses the same virtual gateway IP and MAC on every leaf, allowing a host to move without changing its default gateway.
• ESI multihoming uses the same ESI on all leaf links to a dual-homed server; all-active permits per-flow load sharing.

Worked example

A server dual-homes to leaf1 and leaf2. Configure ae0 on both with the same ESI and all-active, put the server VLAN on an IRB with virtual-gateway-address 10.100.0.1/24 and virtual-gateway-v4-mac 00:00:5e:00:01:01, and map the VLAN to VNI 10100 on both. Matching route targets import Type 2 MAC/IP routes. The shared ESI lets remote peers treat the two links as one segment; the anycast gateway gives the server a consistent first hop.

Traps

A VNI mismatch, missing extended-vni-list, or route-target mismatch breaks reachability while BGP may still look up. Underlay loopbacks must be reachable. Different ESIs on the two leaf links create duplicate-looking multihoming. MTU must accommodate VXLAN encapsulation.