A PCN encoding using 2 DSCPs to provide 3 or more states

Pre-congestion notification (PCN) is a mechanism designed to protect the Quality of Service of inelastic flows within a controlled domain. It does this by marking packets when traffic load on a link is approaching or has exceeded a threshold below the physical link rate. This experimental encoding scheme specifies how three encoding states can be carried in the IP header using a combination of two DSCPs and the ECN bits. The Basic scheme only allows for three encoding states. The Full scheme provides 6 states, enough for limited endto-end support for ECN as well. Status Since its original publication, the baseline encoding ( RFC5696) on which this document depends has become obsolete. The PCN working Group has chosen to publish this as a historical document to preserve the details of the encoding and to allow it to be cited in other documents. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79 . Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current InternetDrafts is at http://datatracker.ietf.org/drafts/current/ . Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 13, 2012. Moncaster, et al. Expires September 13, 2012 [Page 1] Internet-Draft 3 State PCN Encoding March 2012