Testing for Understanding

To test your understanding of ICMPv6, answer the following questions. See Appendix D to check your answers.

1. How do you distinguish ICMPv6 error messages from ICMPv6 informational messages?
2. Which fields of the Echo Request message are echoed in the Echo Reply message?
3. For a maximum-sized IPv6 packet with a Fragment extension header sent on an Ethernet link, how many bytes of the original payload are returned in an ICMPv6 Destination Unreachable message?
4. How can you tell whether a returned packet was discarded by a firewall that is enforcing network policy or a router that could not resolve the link-layer address of the destination?
5. Why is the MTU field in the ICMPv6 Packet Too Big message 4 bytes long when the Next Hop MTU field in the ICMPv4 Destination Unreachable-Fragmentation Needed and DF Set message is only 2 bytes long?
6. Why isn't the ICMPv6 Parameter Problem-Unrecognized Option message sent when the 2 high-order bits of an option's Option Type field are set to either 00 (binary) or 01 (binary)?
7. Based on the IPv6 design requirement to minimize processing at IPv6 routers, why is there no equivalent to the ICMPv4 Source Quench message in IPv6?