Dell PowerConnect B-RX Configuration Manual page 237

Configuring a loopback port for a tunnel interface
On the device, a loopback port is required for de-encapsulating a packet exiting the tunnel.
Fiber-optic components must be present on the interface module for the loopback port to work.
Therefore, consider the following configuration rules for a loopback port:
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To configure a loopback port for a specified tunnel interface, enter the following commands.
BigIron RX(config)# interface tunnel 1
BigIron RX(config-tnif-1)tunnel loopback 3/1
Syntax: tunnel loopback <port-number>
The <port-number> variable is the port number assigned to be the loopback port for the specified
tunnel interface. A loopback port is required to perform termination and forwarding in hardware. If
a loopback port is not configured, tunnel termination is performed by the CPU. When a port is used
as a loopback port for a tunnel, it should not be used for any other purpose.
NOTE
The tunnel loopback port is one of the router's physical ports. It is defined so the GRE packet
processing Is done on by the port's LP CPU instead of the MP's CPU. You can use a 10 GBE port
without a loopback connector but the optical transceiver module MUST be installed. You can use a
1 GBE fiber port, but a physical loopback connector is required. Copper ports are not supported.
Configuring an IP address for a tunnel interface
To configure an IP address for a specified tunnel interface, enter the following command.
BigIron RX(config)# interface tunnel 1
BigIron RX(config-tnif-1)ip address 10.10.3.1/24
Syntax: ip address <ip-address>
The <ip-address> variable is the IP address being configured for the specified tunnel interface.
Example of a GRE IP tunnel configuration
In this example, a GRE IP Tunnel is configured between the device A switch and the device B switch.
Traffic between networks 10.10.1.0/24 and 10.10.2.0/24 is encapsulated in a GRE IP packet sent
through the tunnel on the 10.10.3.0 network. and unpacked and sent the destination network. A
static route is configured at each router to go through the tunnel interface to the target network.
BigIron RX Series Configuration Guide
53-1001986-01
1-gigabit copper ports should not be configured as loopback ports.
1-gigabit and 10-gigabit fiber ports can be configured as loopback port.
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1-gigabit fiber ports require a fiber cable to be connected to itself for loopback to work.
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10-gigabit fiber ports do not require a cable.
Configuring IP parameters
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