The VXLAN-to-VXLAN deployment is where the VXLAN Gateway communicates between VXLAN segments. Use this scenario when one VXLAN segment needs to communicate with another VXLAN segment.
When a packet traverses a VXLAN segment and enters the VXLAN Gateway, the VXLAN VTEP maps one VXLAN segment to another in the following way:
Decapsulates the VXLAN header.
Performs a route lookup of the customer packet.
Identifies that the next hop VLAN is in another VXLAN segment.
Encapsulates the packet with a new VXLAN header with a new VNID.
Forwards the packet out.
The following figure shows two virtualized servers attached to a Layer 3 infrastructure. The servers could be on the same rack, on different racks, or across data centers within the same administrative domain.
There are four VXLAN overlay networks identified by the VNIDs: 22, 34, 74, and 98. Notice how the VMs are associated with a VNID. For example, VM1-1 in Server 1 and VM2-4 on Server 2 are on the same VXLAN overlay network identified by VNID 22.
The VMs do not know about the overlay networks and transport method because the encapsulation and decapsulation happen transparently at the VTEPs on Servers 1 and 2. The other overlay networks and the corresponding VMs are: VM1-2 on Server 1 and VM2-1 on Server 2 both on VNID 34, VM1-3 on Server 1 and VM2-2 on Server 2 on VNID 74, and finally VM1-4 on Server 1 and VM2-3 on Server 2 on VNID 98.
