A GRE tunnel is configured between multiple computing devices of a distributed cloud computing network and a single origin router of the origin network. The GRE tunnel has a first GRE endpoint that has an IP address that is shared among the computing devices of the distribute cloud computing network and a second GRE endpoint that has a publicly routable IP address of the origin router. A first computing device receives an IP packet from a client that is destined to an origin server. The first computing device processes the received IP packet and encapsulates the IP packet inside an outer packet to generate a GRE encapsulated packet whose source address is the first GRE endpoint and the destination address is the second GRE endpoint. The GRE encapsulated packet is transmitted over the GRE tunnel to the single origin router.