3. IP protocol

While the format of IP packets has remained unchanged since its publication in RFC 791 in September 1991, the allocation of some of these fields is still under discussion and continues to evolve. At the same time, a new format has just been standardized, called IPv6. Among other things, it will make it possible to get rid of the constraints associated with the 32-bit size of current addresses, by using addresses four times larger on 128 bits.

In the packet, the fields are aligned on 32-bit words. It's very important to maintain this alignment, as it optimizes packet processing. Suppose...