Software defined networks (SDN) provide flexibility for developing new network protocols and policies in real networks. The SDN controller translates network policies into specific rules in the flow tables (which are usually implemented using ternary content addressable memory (TCAM)) of each networkswitch. However, due to the limitation of TCAM (e.g., high power consumption and high heat generation), flow tables cannot scale beyond a few hundred entries.

Hence, switches usually reactively cache rules (i.e., installing rules on demand). However, reactively caching rules causes packet delay and large buffers, when cache misses happen. To improve the performance, in this paper, we propose a rule partition and allocation algorithm to distribute rules across network switches. Our algorithm not only is applicable to small TCAM switch scenario, but also guarantees semantically-invariant (i.e., the global action of the network is unchanged).

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