Fragmentation threshold refers to the value used in setting the maximum packet size that a client can send without fragmenting the frames it serves to its wireless clients. When a packet exceeds this set size, it is sent as multiple 802.11 frames.
Network performance is significantly affected by the value set as a fragmentation threshold. For example, if the value is small, smaller packets will be sent, which improves reliability but decreases system performance. One should first monitor the wireless LAN for collisions before setting up the fragmentation threshold. If there is an occurrence of relatively large number of frame collusion, then a different fragmentation threshold should be set.