Cisco :: How To Calculate Fragmented Packets

An IP packet of size 1500 bytes passes through two network segments before it reaches its destination. The header size of this packet is 20 bytes. The maximum size of an IP packet in the first intermediate network (its MTU) is 1024 bytes, and that in the second network is 576 bytes.Explain how the IP packet described above would be fragmented into smaller parts in a router, paying particular attention to the flag bits and to the fragment offset field in the header.

- Fragmentation and reassembly needs to break a data-gram into an almost random number of pieces that later can reassembled.
- It uses the identification field to ensure that fragments of different datagrams are not mixed.
- IP packet of 1500 bytes comprises 1480 bytes of data and a 20-byte header.
- In the first intermediate network, the packet size of 1024 bytes allows for 1000 bytes of data plus a 20-byte IP
header.[code]