As computing devices and networks are becoming more powerful and ubiquitous, the networking landscape is evolving into new paradigms such as autonomic networks [1], pervasive networks [2] and grid networks [3]. In these emerging paradigms, network systems will be much more complex and larger than the current ones; the author believes that the capability of network systems is going beyond the capacity of human users and administrators to configure, monitor and understand all aspects of their network systems. Therefore, future network systems need to address fundamental challenges such as autonomy - the ability to operate without human intervention; scalability - the ability to scale to a large number of network hosts and users; adaptability - the ability to adapt to dynamic changes in network conditions (e.g., resource availability and network traffic); survivability - the ability to retain operation and performance despite partial system failures (e.g., network host failures).