Editing Error detection and correction (section)

=== Internet ===
In a typical [[TCP/IP]] stack, error control is performed at multiple levels:
* Each [[Ethernet frame]] uses [[Cyclic redundancy check|CRC-32]] error detection. Frames with detected errors are discarded by the receiver hardware.
* The [[IPv4]] header contains a [[IPv4 header checksum|checksum]] protecting the contents of the header. [[Network packet|Packets]] with incorrect checksums are dropped within the network or at the receiver.
* The checksum was omitted from the [[IPv6]] header in order to minimize processing costs in [[network routing]] and because current [[link layer]] technology is assumed to provide sufficient error detection (see also RFC 3819).
* [[User Datagram Protocol|UDP]] has an optional checksum covering the payload and addressing information in the UDP and IP headers. Packets with incorrect checksums are discarded by the [[network stack]]. The checksum is optional under IPv4, and required under IPv6. When omitted, it is assumed the data-link layer provides the desired level of error protection.
* [[Transmission Control Protocol|TCP]] provides a checksum for protecting the payload and addressing information in the TCP and IP headers. Packets with incorrect checksums are discarded by the network stack and eventually get retransmitted using ARQ, either explicitly (such as through [[three-way handshake]]) or implicitly due to a [[timeout (computing)|timeout]].