This document discusses several proposals to modify TCP for use in mobile environments: 1. Indirect TCP splits the TCP connection to isolate the wireless link but loses end-to-end semantics. 2. Snooping TCP allows local retransmissions through buffering and "snooping" but does not fully isolate the wireless link. 3. Mobile TCP handles disconnections through a supervisory host but does not isolate wireless link losses. 4. Fast retransmit/recovery avoids the slow start algorithm after handovers but mixes network layers. The approaches vary in their ability to isolate the wireless link, efficiency, and amount of modification required to TCP.