IP Fragmentation Reassembly
IP Fragmentation : If the MTU of egress network is less than MTU of packet and DF bit is set to 0, then fragmentation is needed . Fields involved in fragmentation : 1 . Fragment id 2 . offset 3 . Flag Fields changed when fragmentation : Apart from above 3 , following fields are changing in fragmentation 1 . Header length and total length 2 . Header checksum 3 . Options A Packet Fragmentation Example If a 2,366 byte packet enters an Ethernet network with a default MTU size, it must be fragmented into two packets. The first packet will: · Be 1,500 bytes in length. 20 bytes will be the IP header, 24 bytes will be the TCP header, and 1,456 bytes will be data. · Have the DF bit equal to 0 to mean "May Fragment" and the MF bit equal to 1 to mean "More Fragments." · Have a Fragmentation Offset of 0. The second packet will: · Be 910 bytes in length. 20 bytes will be the IP header, 24 bytes will be the TCP header, and 866 bytes will be