Congestion Notification for Pause

This document describes the necessity and feasibility to introduce a mechanism of congestion notification for pause. After receiving the L2 pause frames from the destination data center gateway, the egress provider edge node sends the congestion notifications to the upstream provider nodes and the ingress provider edge node in a format defined in this document. The upstream provider nodes and the ingress provider edge node must pause the forwarding of IP flows identified by the congestion notifications. And then the ingress provider edge node may send the L2 pause frames to the source data center gateway.