"A datagram cannot be larger than the MTU of a network over which it is sent." Is the statement true or false? Explain with the help of a suitable example.

All hardware technology gives the maximum amount of data that a frame can carry. Its limit is termed as maximum transmission unit (i.e.MTU).

Here is no exception to MTU limit, the network hardware is not designed to transfer or to accept frame to carry more data than the MTU al lows. Therefore a datagram should be smaller or identical to network MTU or for transmission it cannot be encapsulated.

An Example of a router which connects two networks with various MTU values.

In figure host H2 attaches to a network which has an MTU of 1000. Hence each datagram which H2 transmits should be 1000 octets or less. Because, however, host HI attaches to a network which has an MTU of 1500 octets, HI can transmit datagram which contains up to 1500 octets. To resolve this problem IP router uses a technique termed as fragmentation. While a datagram is larger than the MTU of a network over that this is sent, the router divides the datagram in smaller pieces termed as fragments and sends each fragment independently. For fragmentation a datagram for transmission across the network, a router uses the network MTU and to calculate maximum amount of data datagram header size which can be sent in each fragment and number of fragment which will be needed.