Skip Links

How to configure a GRE tunnel

By Brad Reese on Tue, 07/15/08 - 10:12pm.

Cisco How-To Tutorials

Tunneling provides a mechanism to transport packets of one protocol within another protocol.

The protocol that is carried is called as the passenger protocol, and the protocol that is used for carrying the passenger protocol is called as the transport protocol.

Generic Routing Encapsulation (GRE) is one of the available tunneling mechanisms which uses IP as the transport protocol and can be used for carrying many different passenger protocols.

The tunnels behave as virtual point-to-point links that have two endpoints identified by the tunnel source and tunnel destination addresses at each endpoint.

Configuring a GRE tunnel involves creating a tunnel interface, which is a logical interface.

Then you must configure the tunnel endpoints for the tunnel interface.

To configure a GRE tunnel, create a tunnel interface by issuing the interface tunnel command from the global configuration mode.

To configure the tunnel source and destination, issue the tunnel source {ip-address | interface-type} and tunnel destination {host-name | ip-address} commands under the interface configuration mode for the tunnel.

For details on GRE tunnel configuration with examples and related information refer to:

Configuring Logical Interfaces

and the

Cisco GRE Technology Support Page

View more Cisco How-To Tutorials

Contact Brad Reese

Search 51,599 current Cisco Job openings worldwide!

Brad's Top 5 Story Picks
# 1. Cisco vs. Nortel: Who's the customer support champ?
# 2. Cisco consummates agreement with legendary reseller CXtec
# 3. Cisco resume tips
# 4. Silver lining in Cisco stock decline: Tough times help Cisco gain market share
# 5. Cisco takes $78M haircut on VMware investment
Story Archives Brad Reese on Cisco Story Archives

Cisco VoIP Gateways

Cisco Power Supplies

Cisco Aironet Wireless

Cisco Refurbished Inventory Availability


On The Web