What happens when a packet exceeds the MTU size?

When a packet exceeds the Maximum Transmission Unit (MTU) size, it is fragmented. The MTU defines the largest size of a packet that can be transmitted over a network segment without needing to be broken down into smaller pieces. If a packet is larger than the MTU, the networking devices such as routers or switches will split the packet into smaller fragments that fit within the allowed size.

This fragmentation process involves splitting the original packet into multiple smaller packets, each of which includes a portion of the original data. Each fragment is transmitted separately and then reassembled at the destination. This mechanism allows for the transmission of larger data packets across networks that have varying limits on packet size, ensuring that data can be communicated effectively without being lost or causing errors.

Transmitting the packet without changes is not feasible if it exceeds the MTU, as it wouldn't conform to the network's requirements. Discarding the packet is typically a last resort and would result in the loss of data, while compression generally reduces data size before transmission but does not specifically deal with MTU-related issues. Therefore, fragmentation is the correct process to manage packets that exceed the MTU size, allowing for successful transmission across diverse network environments.