Internetworking Terms: Generic Routing Encapsulation (GRE)
Generic Routing Encapsulation (GRE)
Tunneling protocol that was developed by Cisco. Generic routing encapsulation (GRE) can encapsulate a variety of protocol packet types inside IP tunnels. This creates a virtual point-to-point link to Cisco routers at remote points over an IP network.
IP tunneling uses GRE to expand networks across a single-protocol backbone environment by connecting multi-protocol subnetworks.