Editing Internet Protocol (section)

==Reliability==
The design of the Internet protocol suite adheres to the [[end-to-end principle]], a concept adapted from the [[CYCLADES]] project. Under the end-to-end principle, the network infrastructure is considered inherently unreliable at any single network element or transmission medium and is dynamic in terms of the availability of links and nodes. No central monitoring or performance measurement facility exists that tracks or maintains the state of the network. For the benefit of reducing [[network complexity]], the intelligence in the network is located in the [[end node]]s.

As a consequence of this design, the Internet Protocol only provides [[best-effort delivery]] and its service is characterized as [[Reliability (computer networking)|unreliable]]. In network architectural parlance, it is a [[connectionless protocol]], in contrast to [[connection-oriented communication]]. Various fault conditions may occur, such as [[data corruption]], [[packet loss]] and duplication. Because routing is dynamic, meaning every packet is treated independently, and because the network maintains no state based on the path of prior packets, different packets may be routed to the same destination via different paths, resulting in [[out-of-order delivery]] to the receiver.

All fault conditions in the network must be detected and compensated by the participating end nodes. The [[upper layer protocol]]s of the Internet protocol suite are responsible for resolving reliability issues. For example, a host may [[Data buffer|buffer]] network data to ensure correct ordering before the data is delivered to an application.

IPv4 provides safeguards to ensure that the header of an IP packet is error-free. A routing node discards packets that fail a header [[checksum]] test. Although the [[Internet Control Message Protocol]] (ICMP) provides notification of errors, a routing node is not required to notify either end node of errors. IPv6, by contrast, operates without header checksums, since current [[link layer]] technology is assumed to provide sufficient error detection.<ref>{{IETF RFC|1726}} section 6.2</ref><ref>{{IETF RFC|2460}}</ref>