Reliability (computer networking): Difference between revisions

Revision as of 14:23, 2 October 2019

Revision as of 20:24, 21 October 2019

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==Reliability properties==

A reliable service is one that notifies the user if delivery fails, while an ''unreliable'' one does not notify the user if delivery fails.{{cn|reason=See [[Talk:Reliability (computer networking)#Latest revision as of 16:16, 25 October 2017 by Kvng]]|date=November 2017}} For example, [[Internet Protocol]] (IP) provides an unreliable service. Together, [[Transmission Control Protocol]] (TCP) and IP provide a reliable service, whereas [[User Datagram Protocol]] (UDP) and IP provide an unreliable one.<!--[[User:Kvng/RTH]]-->

In the context of distributed protocols, reliability properties specify the guarantees that the protocol provides with respect to the delivery of messages to the intended recipient(s).

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An example of a reliability property for a [[unicast]] protocol is "at least once", i.e. at least one copy of the message is guaranteed to be delivered to the recipient.

Reliability properties for [[multicast]] protocols can be expressed on a per-recipient basis (simple reliability properties), or they may relate the fact of delivery or the order of delivery among the different recipients (strong reliability properties). In the context of multicast protocols, strong reliability properties express the guarantees that the protocol provides with respect to the delivery of messages to different recipients.

In the context of multicast protocols, strong reliability properties express the guarantees that the protocol provides with respect to the delivery of messages to different recipients.

An example of a strong reliability property is ''last copy recall'', meaning that as long as at least a single copy of a message remains available at any of the recipients, every other recipient that does not fail eventually also receives a copy. Strong reliability properties such as this one typically require that messages are retransmitted or forwarded among the recipients.

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One of the most complex strong reliability properties is [[virtual synchrony]].

Strong reliability properties are offered by [[group communication system]]s (GCSGCSs) such as [[IS-IS]], [[Appia framework]], [[Spread (group communication system)|Spread]], [[JGroups]] or [[QuickSilver Scalable Multicast]]. The [[QuickSilver Properties Framework]] is a flexible platform that allows strong reliability properties to be expressed in a purely declarative manner, using a simple rule-based language, and automatically translated into a hierarchical protocol.<!--[[User:Kvng/RTH]]-->

==Asynchronous Transfer Mode==