Best-effort delivery

Best-effort delivery describes a network service in which the network does not provide any guarantees that data is delivered or that a user is given a guaranteed quality of service level or a certain priority. In a best-effort network all users obtain best-effort service, meaning that they obtain unspecified variable bit rate and delivery time, depending on the current traffic load. It can be contrasted with reliable delivery, which can be built on top of best-effort delivery (possibly without latency and throughput guarantees), or with circuit switching schemes which maintain a defined, continuous quality of service.

Examples

The postal service delivers letters using a best-effort delivery approach. The delivery of a certain letter is not scheduled in advance – no resources are preallocated in the post office. The service will make their "best effort" to try to deliver a message, but the delivery may be delayed if too many letters arrive to a postal office suddenly. The sender is not informed if a letter has been delivered successfully.