Tunneling

Tunneling is the act act of running traffic through a logical network tunnel, removing the transparency of the forwarding network and allowing for functionalities such as protocol-support, security or traffic-shaping.

Typically, tunnels are realized by appending a header to a packet, which the transporting network utilizes to route the packet to the other end of the tunnel, where the extra header is removed and the original packet is routed further.

In the lab, we utilize this functionality to append an IPv4 header to an IPv6 packet, to allow IPv6 packets to be routed through an IPv4 network. To apply this, we utilize an SIT (Simple Internet Transition) tunnel.

In the lab, this tunnel is applied on VyOS devices and follow the following configuration syntax:

set interfaces tunnel tun0 address 'IPV6_ADDRESS_OF_TUNNEL'
set interfaces tunnel tun0 encapsulation 'sit'
set interfaces tunnel tun0 local-ip 'LOCAL_IPV4_ADDRESS_TOWARD_TRANSPORT_NETWORK'
set interfaces tunnel tun0 remote-ip 'REMOTE_IPV4_ADDRESS_IN_TRANSPORT_NETWORK'

The tunnel acts as its own network on the router, and can use a lot of the same functionality that an ethernet interface would use.