{"draft":"draft-ietf-ntp-checksum-trailer-07","doc_id":"RFC7821","title":"UDP Checksum Complement in the Network Time Protocol (NTP)","authors":["T. Mizrahi"],"format":["ASCII","HTML"],"page_count":"14","pub_status":"EXPERIMENTAL","status":"EXPERIMENTAL","source":"Network Time Protocols","abstract":"The Network Time Protocol (NTP) allows clients to synchronize to a\r\ntime server using timestamped protocol messages.  To facilitate\r\naccurate timestamping, some implementations use hardware-based\r\ntimestamping engines that integrate the accurate transmission\r\ntime into every outgoing NTP packet during transmission.  Since\r\nthese packets are transported over UDP, the UDP Checksum field is\r\nthen updated to reflect this modification.  This document proposes an\r\nextension field that includes a 2-octet Checksum Complement, allowing\r\ntimestamping engines to reflect the checksum modification in the last\r\n2 octets of the packet rather than in the UDP Checksum field.  The\r\nbehavior defined in this document is interoperable with existing NTP\r\nimplementations.","pub_date":"March 2016","keywords":["NTP","UDP","Checksum","timestamping"],"obsoletes":[],"obsoleted_by":[],"updates":[],"updated_by":["RFC9748"],"see_also":[],"doi":"10.17487\/RFC7821","errata_url":null}