IPv6 has been an inevitable trend with the depletion of the global IPv4 address space. However, new IPv6 users still need public IPv4 addresses to access global IPv4 users/resources, making it important for providers ...IPv6 has been an inevitable trend with the depletion of the global IPv4 address space. However, new IPv6 users still need public IPv4 addresses to access global IPv4 users/resources, making it important for providers to share scarce global IPv4 addresses effectively. There are two categories of solutions to the problem, carrier-grade NAT （CGN） and ＇A＋P＇ （each customer shaving the same IPv4 address is assigned an excluded port range）. However, both of them have limitations. Specifically, CGN solutions are not scalable and can bring much complexity in managing customers in large-scale deployments, while A＋P solutions are not flexible enough to meet dynamic port requirements. In this paper, we propose a hybrid mechanism to improve current solutions and have deployed it in the Tsinghua University Campus Network. The real traffic data shows that our mechanism can utilize limited IPv4 addresses efficiently without degrading the performance of applications on end hosts. Based on the enhanced mechanism, we propose a method to help service providers make address plans based on their own traffic patterns and actual requirements.展开更多
Limit language complexity of cellular automata which is first posed by S. Wolfram has become a new branch of cellular automata. In this paper, we obtain two interesting relationships between elementary cellular automa...Limit language complexity of cellular automata which is first posed by S. Wolfram has become a new branch of cellular automata. In this paper, we obtain two interesting relationships between elementary cellular automata of rules 126, 146（182） and 18, and prove that if the limit language of rule. 18 is not regular, nor are the limit languages of rules 126 and 146（182）.展开更多
文摘IPv6 has been an inevitable trend with the depletion of the global IPv4 address space. However, new IPv6 users still need public IPv4 addresses to access global IPv4 users/resources, making it important for providers to share scarce global IPv4 addresses effectively. There are two categories of solutions to the problem, carrier-grade NAT （CGN） and ＇A＋P＇ （each customer shaving the same IPv4 address is assigned an excluded port range）. However, both of them have limitations. Specifically, CGN solutions are not scalable and can bring much complexity in managing customers in large-scale deployments, while A＋P solutions are not flexible enough to meet dynamic port requirements. In this paper, we propose a hybrid mechanism to improve current solutions and have deployed it in the Tsinghua University Campus Network. The real traffic data shows that our mechanism can utilize limited IPv4 addresses efficiently without degrading the performance of applications on end hosts. Based on the enhanced mechanism, we propose a method to help service providers make address plans based on their own traffic patterns and actual requirements.
基金This research is supported by the National Natural Science Foundation of China(10101016).
文摘Limit language complexity of cellular automata which is first posed by S. Wolfram has become a new branch of cellular automata. In this paper, we obtain two interesting relationships between elementary cellular automata of rules 126, 146（182） and 18, and prove that if the limit language of rule. 18 is not regular, nor are the limit languages of rules 126 and 146（182）.
