scope:

This document describes a mechanism for aggregation and fragmentation of IP packets when they are being encapsulated in Encapsulating Security Payload (ESP). This new payload type can be used for various purposes, such as decreasing encapsulation overhead for small IP packets; however, the focus in this document is to enhance IP Traffic Flow Security (IP-TFS) by adding Traffic Flow Confidentiality (TFC) to encrypted IP-encapsulated traffic. TFC is provided by obscuring the size and frequency of IP traffic using a fixed-size, constant-send-rate IPsec tunnel. The solution allows for congestion control, as well as nonconstant send-rate usage.