Improving network flow definition: Formalization and applicability

Network flow monitoring has been used for more than 20 years and has become an important part of network accounting and security. A significant effort was invested into the standardization of flow monitoring by the Internet Engineering Task Force (IETF). The flow monitoring has steadily evolved to satisfy new requirements created by the demand for increased visibility and accuracy. Therefore, it is not surprising that even the most recent flow definition created by the IETF does not consider several specifics of the flow monitoring process as it is used nowadays. This paper presents a revised flow definition that is more generic and is designed to accommodate more specific flow monitoring requirements. Moreover, we formalize our definition to avoid ambiguity and imprecision introduced by the use of natural language. One additional benefit of formalizing the flow definition is that it implicitly describes the flow creation process as well.