generic routing encapsulation. Tunneling protocol developed by Cisco that can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP internetwork.
Technology Information

Design

Configure

Configuration Examples and TechNotes

(All IP Tunneling Configuration Examples and TechNotes)

(All IP Tunneling Configuration Examples and TechNotes)
Configuring a GRE Tunnel over IPsec with OSPF

Configuring CET Encryption with a GRE Tunnel

Configuring Dynamic Multipoint VPN Using GRE Over IPSec With EIGRP, NAT, and CBAC

Configuring Dynamic Multipoint VPN Using GRE Over IPsec With OSPF, NAT, and Cisco IOS Firewall

Configuring GRE and IPSec with IPX Routing

Configuring GRE Over IPSec Between a Cisco IOS Router and a VPN 5000 Concentrator Using Dynamic Routing

Configuring GRE over IPSec Between a Cisco IOS Router and a VPN 5000 Concentrator Using Static Routing

Configuring IPSec with EIGRP and IPX Using GRE Tunneling

Configuring Router-to-Router IPsec (Pre-shared Keys) on GRE Tunnel with IOS Firewall and NAT

Configuring the Cisco VPN 5000 and a Router to Open a GRE Tunnel

Configuring Two Cisco VPN 5000 Series Concentrators to Establish a GRE Tunnel

Configuring Two Cisco VPN 5000 Series Concentrators to Establish a GRE Tunnel Routing IPX

Configuring Two Cisco VPN 5000 Series Concentrators to Establish an IPSec LAN-to-LAN Tunnel Routing IPX

GRE over IPSec with EIGRP to Route Through a Hub and Multiple Remote Sites Configuration Example

IPSec/GRE with NAT on IOS Router Configuration Example

Multicast over a GRE Tunnel

Configuring CET Encryption with a GRE Tunnel
Configuring Dynamic Multipoint VPN Using GRE Over IPSec With EIGRP, NAT, and CBAC
Configuring Dynamic Multipoint VPN Using GRE Over IPsec With OSPF, NAT, and Cisco IOS Firewall
Configuring GRE and IPSec with IPX Routing
Configuring GRE Over IPSec Between a Cisco IOS Router and a VPN 5000 Concentrator Using Dynamic Routing
Configuring GRE over IPSec Between a Cisco IOS Router and a VPN 5000 Concentrator Using Static Routing
Configuring IPSec with EIGRP and IPX Using GRE Tunneling
Configuring Router-to-Router IPsec (Pre-shared Keys) on GRE Tunnel with IOS Firewall and NAT
Configuring the Cisco VPN 5000 and a Router to Open a GRE Tunnel
Configuring Two Cisco VPN 5000 Series Concentrators to Establish a GRE Tunnel
Configuring Two Cisco VPN 5000 Series Concentrators to Establish a GRE Tunnel Routing IPX
Configuring Two Cisco VPN 5000 Series Concentrators to Establish an IPSec LAN-to-LAN Tunnel Routing IPX
GRE over IPSec with EIGRP to Route Through a Hub and Multiple Remote Sites Configuration Example
IPSec/GRE with NAT on IOS Router Configuration Example
Multicast over a GRE Tunnel