http://www.rfc-editor.org/rfc/rfc4938.txt
RFC 4938: PPP Over Ethernet (PPPoE) Extensions for Credit Flow and Link Metrics, B. Berry, H. Holgate2007-06-01T23:00:00-00:00This document extends the Point-to-Point over Ethernet (PPPoE) Protocol with a credit-based flow control mechanism and Link Quality Metric report. This optional extension should improve the performance of PPPoE over media with variable bandwidth and limited buffering, such as mobile radio links. This memo provides information for the Internet community.