It is said that when IPv6 tunnels through IPv4 routers, IPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?
Try an answer before revealing the guidance below.
Key Concepts
- Tunneling
- Encapsulation
- IPv6 datagram as payload
- Logical link
Answer Approach
- Describe what the tunnel entry router does with the IPv6 datagram.
- Compare this with how a link-layer frame carries a datagram.
- Ask what the IPv6 routers see between the tunnel endpoints.
Full Answer
Answer status: Draft answer (unofficial). Revision notes, not an official marking scheme.
Agree. The whole IPv6 datagram, header included, is carried as the payload of an IPv4 datagram between the tunnel endpoints, just as a link-layer frame carries a datagram. From the IPv6 routers’ point of view the entire IPv4 path is a single logical link (one hop) between the two tunnel endpoints.
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