
The IPv4 specification defines the minimal requirements. Image by Geoff Huston, reproduced with permission This process is called "forward" IP fragmentation and the smaller datagrams are called IP fragments. When a packet is too big for a physical link, an intermediate router might chop it into multiple smaller datagrams in order to make it fit. What is the maximum permitted datagram size that can be safely pushed through the physical connections between the hosts? What is the maximum packet size that can be handled by operating systems on both ends? The idea was to split the problem into two separate concerns:

This is an old question and the IPv4 RFCs answer it pretty clearly.


As opposed to the public telephone network, the internet has a Packet Switched design.
