Best effort delivery
Encyclopedia
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.
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 mailman will make his "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.
Conventional telephone networks are not based on best-effort communication, but on circuit switching
. During the connection phase of a new call, resources are reserved in the telephone exchange
s, or the user is informed that the call is blocked due to lack of free capacity. An ongoing phone call can never be interrupted due to overloading of the network, and is guaranteed constant bandwidth.
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
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.
The postal service
Mail
Mail, or post, is a system for transporting letters and other tangible objects: written documents, typically enclosed in envelopes, and also small packages are delivered to destinations around the world. Anything sent through the postal system is called mail or post.In principle, a 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 mailman will make his "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.
Conventional telephone networks are not based on best-effort communication, but on circuit switching
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
. During the connection phase of a new call, resources are reserved in the telephone exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
s, or the user is informed that the call is blocked due to lack of free capacity. An ongoing phone call can never be interrupted due to overloading of the network, and is guaranteed constant bandwidth.
Book sources
- Encyclopedia of Networking & Telecommunications ISBN 0-07-212005-3