Cisco Nexus 7000 Series Configuration Manual page 54

End Host and Subnet Route Distribution
• When a new end host is attached to a VTEP (say Host A in the below scenario), the VTEP V1 learns
the end host's MAC and IP address. MP-BGP on the VTEP nodes enables advertising of the addresses
(IP + MAC) to the route reflector.
Figure 8: New End Host Attaches to a VTEP
• MP-BGP also distributes subnet routes and external reachability information between VTEPs. When
VTEPs obtain end host routes of remote end hosts attached to other VTEPs, they install the routes in
their RIB and FIB.
Note that the end host route distribution is decoupled from the underlay protocol.
End host communication within a VNI and across VNIs
As we know, in a VXLAN EVPN fabric a unique Layer-2 VNI is designated to each tenant network.
Recall, when two end hosts sharing the same layer-2 VNI communicate with each other, the traffic is bridged,
and confined to a subnet. When two end hosts in different layer-2 VNIs communicate with each other, the
traffic is routed and moves between subnets.
Furthermore, an end host retains its address and tenant association when it moves to another VTEP.
One tenant network, one Layer-2 VNI, and one default gateway IP and MAC address
Since end hosts in a tenant network might be attached to different VTEPs, the VTEPs are made to share a
common gateway IP and MAC address for intra-tenant communication.
If an end host moves to a different VTEP, the gateway information remains the same and reachability
information is available in the BGP control plane.
Cisco Nexus 7000 Series NX-OS VXLAN Configuration Guide
46
Configuring VXLAN BGP EVPN