Telemetry on a city leaf-spine path shows the outer IP TTL of VXLAN packets decrementing at each underlay hop. What does that indicate about the data plane?
Select an answer to reveal the explanation.
Short Explanation
The outer TTL is the underlay’s hop counter—the truck’s odometer, not the letter inside. Each underlay router ticks it down while shipping UDP/IP toward the far VTEP. That is normal IP behavior, not proof the overlay is being terminated on every spine.
Full Explanation
VXLAN encapsulation places the original frame inside UDP/IP. Intermediate underlay devices forward based on the outer IP header and decrement outer TTL just as they would for any IP packet. They do not need to parse or terminate the tenant overlay on each hop. Observing outer TTL changes along the path confirms underlay IP forwarding of encapsulated traffic, which is expected in a Clos fabric.