What is the function of the 'Flags' field in the IPv4 header?

The 'Flags' field in the IPv4 header plays a crucial role in controlling fragmentation, which is the process of breaking a packet into smaller pieces to accommodate the maximum transmission unit (MTU) size of a network segment. The Flags field consists of three bits: one bit indicates whether fragmentation is allowed, while the other two bits are used to control the fragmentation process.

When a packet is too large to be transmitted over a network, the Flags field helps by indicating if the packet can be fragmented or if it is the last fragment of a large packet. Specifically, the "More Fragments" bit is set if there are more fragments following the current fragment, allowing the receiving end to correctly reassemble the original packet.

Understanding this function is important for network professionals because proper handling of fragmentation is essential for efficient data transmission across varied network types and conditions, ensuring that packets arrive intact and in the correct order.