In this illustration, we see a desktop computer connected to a router, and that router connected to a second router. Between the routers is a long blue rectangle that represents a large datagram. This part of the figure is labeled "Fragmentation: In: one large datagram (4,000 bytes). Out: 3 smaller datagrams." Between the second router and a third, the long blue rectangle has become three small rectangles. These are labeled "Link MTU: 1,500 bytes." The third router connects to a fourth, and here we see the three small rectangles headed towards a destination computer. By the time they've arrived, they have been restored to a single long rectangle. This part of the figure is labeled "Reassembly: In: 3 smaller datagrams. Out: one large datagram (4,000 bytes)."