a route from source to destination and a "backward ant" returns over this route updating the tables in each intermediate node. Proactive routing Ants are periodically generated to proactively sample and information gathering optimise existing routes as well as discover alternative routes. Pheromone tables are updated to continuously optimise and evolve routing decisions as well as to respond to disruptive events. Stochastic routing When several alternative paths are available for a data decisions packet's next hop, a path is selected stochastically, giving higher probability to the path with the highest pheromone table value. This leads to automatic load balancing, since data is distributed across all good paths, and if one becomes overloaded it will be avoided until the congestion eases. Network Independent Roaming Media Independent Handoff In the Section "Network Performance and Roaming (802.11k and 802.11r), p. 162", three situations were described where client stations need to make transitions between WLAN access points; for mobile client stations moving out of range of a current access point, to maintain service availability under changing environmental conditions or service needs, or for load balancing within the WLAN. Transitions between points of attachment (POA) for a single network type (such as an 802.11 WLAN) are termed homogeneous transitions, and in the case of 802.11 networks, Task Groups TGk and TGr are developing and enhancing the mechanisms that enable seamless WLAN transitions. Chapter Fourteen Table 14-2: Roaming Needs Requiring Heterogeneous Transitions Roaming need Description Mobile client; A client station may move out of range of its current POA, and coverage need to transition to another network type because the current type is no longer available; e.g. moving out of range of an 802.11 hotspot and transitioning to a cellular phone service to maintain a voice connection. Mobile client; A mobile client may move into range of an alternative network cost advantage that is able to provide the