Dell PowerConnect 8024 User Configuration Manual page 859

Loopback Interfaces
When packets are sent to the loopback IP address, the network should be able
to deliver the packets as long as any physical interface on the switch is up.
There are many cases where you need to send traffic to a switch, such as in
switch management. The loopback interface IP address is a good choice for
communicating with the switch in these cases because the loopback interface
cannot go down when the switch is powered on and operational.
Tunnel Interface
Tunnels can be used in networks that support both IPv6 and IPv4. The tunnel
allows non-contiguous IPv6 networks to be connected over an IPv4
infrastructure.
859
Configuring Routing Interfaces