This document specifies the IPFIX protocol that serves for transmitting IP traffic flow information over the network. In order Aitken, Claise Standard Track [page 1] New Information Elements for the IPFIX Information Model March 2008 to transmit IP traffic flow information from an exporting process to an information collecting process, a common representation of flow data and a standard means of communicating them is required. This document describes how the IPFIX data and templates records are carried over a number of transport protocols from an IPFIX exporting process to an IPFIX collecting process. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].