Container-based clouds have recently received great attention from the industry. However, we notice that this new type of cloud inevitably requires complex network setups and configurations from both providers and customers when deployed on an existing cloud system; Providers need to install additional network elements such as proxy servers and Network Address Translation (NAT), and customers need to use subdomain names and randomly assigned port numbers to access their services. Thus, we propose a new network architecture that performs M-to-N mapping between network addresses and containers in order to simplify the network setup and configuration. To achieve our goals, we adopt a software-defined networking (SDN) approach. We discuss the benefits and use cases of our approach, and present detailed designs and implementation.