Ingress and egress sFlow for transit nodes

Ingress and egress sFlow for transit nodes are supported for IPv4-in-IPv4, IPv6-in-IPv4, and regular IPv4/IPv6 traffic. In transit-only devices, the IP-in-IP encapsulated packet can transit through the device without any change or might get de-encapsulated and forwarded or de-encapsulated and encapsulated and forwarded based on the next-hop configuration. Additionally, the packet might traverse through multiple VRF instances while getting forwarded. The router supports ingress and egress sFlow for all those variations.