Best-effort delivery

Best-effort delivery describes a network service in which the Network does not provide any special features that recover lost or corrupted packets. These services are instead provided by end systems. By removing the need to provide these services, the network operates more efficiently.

Best-effort delivery at work

The postal service delivers letters using a best-effort delivery approach. You don't know for sure whether a letter has been delivered. However, you can pay extra for a delivery confirmation receipt, which requires that the carrier get a signature from the recipient and return it to you.

In a very similar way, the Best-effort delivery it's implemented in the mobile phones Short Message Service. Since there are thousands of subscribers per operator the messages need to be delivered Efficient,fast and with minimum of expense.

In computer networking the TCP/IP protocol suite, TCP provides guaranteed services while IP provides best-effort delivery. TCP performs the equivalent of obtaining a delivery confirmation from the recipient and returning it to the sender. Because IP provided basic packet delivery services without guarantees, it is called a best-effort delivery service. It does its best to deliver packets to the destination, but takes no steps to recover packets that are lost or misdirected.

Book sources

Encyclopedia of networking & telecommunications ISBN 0072120053