IP Data Delivery

IP protocol does not an assurance that all packets that are sent to the destination are, in fact, received. IP has unreliable data delivery. It's mean that IP does not have the ability to handle and recover from undelivered or corrupt packets. Because IP header has no such information about the location of delivery. IP header has also no information that can be processed to inform the sender whether the packet was successfully received at the destination. Packets received at the destination may be corrupted, out of sequence or not at all. IP also provides no capability for packet retransmissions if errors occur.

If the destination received in out-of-order packets, or packets are missing, upper layer helps to resolve the problem. Upper layer or application help IP to function very efficiently. In the TCP/IP protocol suite, the reliability of data transmission is the role of the transport layer.