Protocols and standards
RFC 1701, Generic Routing Encapsulation (GRE)
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RFC 1702, Generic Routing Encapsulation over IPv4 networks
RFC 2784, Generic Routing Encapsulation (GRE)
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Configuring a GRE over IPv4 tunnel
Configuration prerequisites
On each of the peer devices, configure an IP address for the interface to be used as the source
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interface of the tunnel interface (for example, a VLAN interface or a loopback interface), and make
sure this interface can normally communicate with the interface used as the source interface of the
tunnel interface on the peer device.
Create a service loopback group, specify its service type as tunnel, and add an available Layer 2
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Ethernet port to the service loopback group. For more information about the service loopback group,
see Layer 2—LAN Switching Configuration Guide.
Configuration guidelines
The source address and destination address of a tunnel uniquely identify a path. They must be
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configured at both ends of the tunnel and the source address at one end must be the destination
address at the other end and vice versa.
The source address or interface and the destination address that are specified for the tunnel
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interface must be a public address or interface.
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Tunnel interfaces using the same encapsulation protocol must have different source addresses and
destination addresses.
If you configure a source interface for a tunnel interface, the tunnel interface takes the primary IP
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address of the source interface as its source address.
When configuring a route through the tunnel, you are not allowed to set up a static route whose
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destination address is in the subnet of the tunnel interface. Instead, you can do one of the following:
Configure a static route, using the address of the network segment that the original packet is
destined for as its destination address and the address of the peer tunnel interface as its next
hop.
Enable a dynamic routing protocol on both the tunnel interface and the router interface
connecting the private network, so that the dynamic routing protocol can establish a routing
entry that allows the tunnel to forward packets through the tunnel.
Configuration procedure
To configure a GRE over IPv4 tunnel:
Step
1.
Enter system view.
2.
Create a tunnel interface and
enter tunnel interface view.
Command
system-view
interface tunnel interface-number
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Remarks
N/A
By default, a device has no tunnel
interface.