What happens to IPv4 packets that exceed the Maximum Transmission Unit?

When IPv4 packets exceed the Maximum Transmission Unit (MTU), they are fragmented. The MTU is the largest size a packet can be for a network medium to handle without requiring fragmentation. In a scenario where a packet exceeds this size, the internet protocol (IP) must break it down into smaller fragments that can fit within the MTU limitations.

Fragmentation occurs at the IP layer; the original packet is divided into smaller packets known as fragments, which are then transmitted separately across the network. Each fragment contains enough information in its header to allow the receiving device to reassemble the original packet correctly. This process ensures that large packets can still be delivered over networks with smaller MTU sizes, maintaining the integrity of the transmission and ensuring communication can continue effectively.

Therefore, if a packet is too large for the MTU, fragmentation is the necessary solution that allows it to be transmitted across the network reliably.