Hi, I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comment.   This memo describes a mobile communications use case for congestion exposure (ConEx) with a particular focus on those mobile communication networks that are architecturally similar to the 3GPP Evolved Packet System (EPS).    I have the following comments: l   1. It should be helpful to consider the communication security between the ConEx senders and receivers such as the Confidentiality, data integrity and peer entity authentication in the security considerations part. Because in general, the corresponding risks are still possible to exist. l   2. The authentication mechanism among all the elements of ConEx solution should also be considered to handle the condition of faked messages or invalid peer elements.   Recommendation:  Ready With Issues   B.R. Frank