Survey of Proposed Use Cases for the IPv6 Flow Label The IPv6 protocol includes a flow label in every packet header, but this field is not used in practice. This paper describes the flow label standard and discusses the implementation issues that it raises. It then describes various published proposals for using the flow label and shows that most of them are inconsistent with the standard. Methods to address this problem are briefly reviewed. We also question whether the standard should be revised. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at