Implementing Cisco Networking Solutions

Configuring overlay P2P links

Sometimes the internet is used as the network to create a point-to-point link as an overlay. This is done using technologies such as Generic Routing Encapsulation (GRE), where an IP packet is used as the payload and is encapsulated within another IP header to be transported from the source to the destination. The outer IP header transports the actual IP packet payload from the source to the destination on the basis of the source and destination address fields of the outer header. This is used to create overlay circuits over routed networks such as the internet. The payload packet is "tunneled" through the layer 3 network, and hence this is also known as tunneling, with the interface so created referred to as ...