http://www.rfc-editor.org/rfc/rfc6431.txt
RFC 6431: Huawei Port Range Configuration Options for PPP IP Control Protocol (IPCP), M. Boucadair, P. Levis, G. Bajko, T. Savolainen, T. Tsou2011-11-01T23:00:00-00:00This document defines two Huawei IPCP (IP Control Protocol) options used to convey a set of ports. These options can be used in the context of port range-based solutions or NAT-based solutions for port delegation and forwarding purposes. This document is not an Internet Standards Track specification; it is published for informational purposes.