A method, performed by a router device (700, 101), the method comprising: - configuring a first loopback interface and assigning an internal Virtual Route Forwarder, VRF1, to the first loopback interface; - configuring a second loopback interface and assigning an internal Virtual Route Forwarder, VRF2, to the second loopback interface; said internal VRF2 being different from the internal VRF1; - creating or configuring at least a first Generic Routing Encapsulation, GRE, tunnel and a second GRE tunnel to be used by interfaces within the router device; - assigning the first GRE tunnel to the internal VRF1 and assigning the second GRE tunnel to the internal VRF2; - for the first GRE tunnel, assigning the first loopback interface as a source point of the first GRE tunnel and assigning the second loopback interface as a destination point of the first GRE tunnel; - for the second GRE tunnel, assigning the second loopback interface as a source point of the second GRE tunnel and assigning the first loopback interface as a destination point of the second GRE tunnel; - configuring a source Internet Protocol, IP, address and a destination IP address of both the first GRE tunnel and the second GRE tunnel to use the same routing table from a routing table of VRF1 or from a routing table of VRF2; - creating or configuring a first static route on VRF1 to route data packets destined to a network behind VRF2 by defining the IP address of the second GRE tunnel as the destination IP address in the first static route; and - creating or configuring a second static route on VRF2 to route data packets destined to a network behind VRF1 by defining the IP address of the first GRE tunnel as the destination IP address in the second static route. - configuring a first loopback interface and assigning an internal Virtual Route Forwarder, VRF1, to the first loopback interface; - configuring a second loopback interface and assigning an internal Virtual Route Forwarder, VRF2, to the second loopback interface; said internal VRF2 being different from the internal VRF1; - creating or configuring at least a first Generic Routing Encapsulation, GRE, tunnel and a second GRE tunnel to be used by interfaces within the router device; - assigning the first GRE tunnel to the internal VRF1 and assigning the second GRE tunnel to the internal VRF2; - for the first GRE tunnel, assigning the first loopback interface as a source point of the first GRE tunnel and assigning the second loopback interface as a destination point of the first GRE tunnel; - for the second GRE tunnel, assigning the second loopback interface as a source point of the second GRE tunnel and assigning the first loopback interface as a destination point of the second GRE tunnel; - configuring a source Internet Protocol, IP, address and a destination IP address of both the first GRE tunnel and the second GRE tunnel to use the same routing table from a routing table of VRF1 or from a routing table of VRF2; - creating or configuring a first static route on VRF1 to route data packets destined to a network behind VRF2 by defining the IP address of the second GRE tunnel as the destination IP address in the first static route; and - creating or configuring a second static route on VRF2 to route data packets destined to a network behind VRF1 by defining the IP address of the first GRE tunnel as the destination IP address in the second static route.