Hello, everyone.
About Path MTU Discovery. If the client notices that its 1500-byte packet was dropped because the MTU was lowered somewhere to 1476 (or just a lower value), what exactly will it do with the 1500-byte data? It won’t fragment them, right? Will it just break the packet down into smaller pieces, or? But that’s fragmentation, isn’t it? And that’s undesired. 
Or is it safe to say that fragmentation or reassembly is okay on the hosts as they have time to do all that but not on a networking device like a router whose job is to forward packets as fast as possible?
Also, when a packet fragment is dropped, why do we retransmit the entire packet and not just the fragment?
Thank you.
David