Key Concept: There are two approaches to handling retransmission in TCP. In the more “conservative” approach, only the segments whose timers expire are retransmitted; this saves bandwidth but may cause performance degradation if many segments in a row are lost. The alternative is that when a segment’s retransmission timer expires, both it and all subsequent unacknowledged segments are retransmitted. This provides better performance if many segments are lost but may waste bandwidth on unnecessary retransmissions.