This illustration of tunneling includes two views: a logical view and a physical view. In the logical view, we see a series of routers in a horizontal line, each connected to the other. From left to right, we see: router A, labeled "IPv6;" router B, labeled "IPv6;" a long gray tube, labeled "Tunnel;" followed by routers E and F, both labeled "IPv6."

In the physical view, we see a similar series of connected routers, though this time without the tunnel. Starting at the left, we see router A, labeled "IPv6." We also see a data packet moving from A towards B; the packet is labeled "A to B: IPv6," and this data packet contains the following information:

Flow: X

Source: A

Dest: F

data

Next we see router B, similarly labeled "IPv6," and similarly with a data packet moving from B towards C. This packet is labeled "B to C: IPv4 (encapsulating IPv6)" and contains the following information:

Flow: X

Source: A

Dest: F

data

Next we see routers C and D, both labeled "IPv4." A data packet moves from D towards E; this packet is labeled "D to E: IPv4 (encapsulating IPv6)," and includes the following information:

Flow: X

Source: A

Dest: F

data

Next we see router E, labeled "IPv6." A data packet moves from E towards F; this packet is labeled "E to F: IPv6," and includes the following information:

Flow: X

Source: A

Dest: F

data

The data arrives at router F.