Drawbacks of Fragmentation

• Lose one fragment, lose the whole packet

• • Timeout and retransmission occurs at layer 4 and above
  • • Fragmentation occurs transparently to higher layers

• Additional latency

• • Wait for all fragments to arrive
  • Re-assembly delay

• TCP tries to avoid all fragmentation

• • Discovers path MTU
  • Lost or out-of-order fragments would make TCP’s behavior even more complex