Packet Fragmentation Differences Between IPv6 and IPv4
Question
What are two ways that packet fragmentation is handled differently between IPv6 and IPv4? (Choose two.)
Answers
Explanations
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A. B. C. D.AC
IPv4 and IPv6 handle packet fragmentation differently. IPv4 uses packet fragmentation at intermediate nodes while IPv6 end hosts determine the path MTU.
In IPv4, when a packet is larger than the Maximum Transmission Unit (MTU) of a link it is transmitted on, the router will fragment the packet into smaller packets that fit the link MTU. This process is repeated at each router until the packet reaches its destination. Fragmentation at intermediate nodes is resource-intensive and can cause latency issues, and hence, it is preferable to avoid fragmentation whenever possible.
IPv6, on the other hand, uses Path MTU Discovery (PMTUD) mechanism to avoid fragmentation. End hosts determine the path MTU by sending packets with a large packet size and listening for "packet too big" messages from intermediate nodes. If the sender receives such a message, it reduces the packet size and sends it again. This process continues until the packet size is small enough to avoid fragmentation. The PMTUD mechanism avoids fragmentation at intermediate nodes and reduces the processing overhead.
Therefore, the correct answers are: A. End hosts determine the path MTU for IPv6. D. Packet fragmentation occurs at intermediate nodes for IPv6.
