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On a router-port basis, our previous study  found that lightpath bypass strategy can significantly save power consumption over the lightpath non-bypass strategy. However, in real network systems, router ports are organized by network line cards or modules; on each line card there are multiple router ports. In this paper, we evaluate the energy consumption of an IP over WDM network in the context of modularized router ports. We develop mixed integer linear programming (MILP) model for power consumption minimization under the lightpath bypass strategy. We also compare the cases of lightpath bypass and nonbypass. It is found that for modularized route ports, the strategy of optical bypass can significantly outperform the strategy of non-bypass. Also, under different types of modular router line cards, a mixed deployment of different types of router line cards consumes the least energy compared to the deployment of a single type of line card.