Luchetti, Riccardo; Amadio, Peter C.
The amusement park tunnel of love is attested from 1911 in reference to New York's Luna Park.
Before GRE keepalives were implemented, there were only ways to determine local issues on the router and no way to determine problems in the intervening network.
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This reveals the pre-made keepalive reply, which then needs to be forwarded back to the sender, BUT that forwarding is in the context of the iVRF on the tunnel interface.
Since Peer A uses tunnel protection on the tunnel interface, the keepalive packet is not encrypted.