VXLAN Traffic Trombone

I like the name given by one of the commenter’s on blog.scottlowe.org; it describes the traffic route in the following VXLAN example diagram

VXLAN traffic trombone

Note that even though the Windows-based workload inside the VXLAN segment now resides on a completely separate VTEP (ESXi 2, in this case), the traffic from the Linux-based workload outside the VXLAN segment continues to move through VSE 1. That’s because VSE 1 is still the Layer 3 default gateway for the IP subnet inside the VXLAN segment. Therefore—and this is where I was wrong earlier—Layer 3 connectivity is not broken, but it does have to “horseshoe” across to the other data center and then back again, as illustrated above. This is the classic traffic pattern that we see with other overlay technologies, like OTV.

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