Communication in the data center today is often based on the network running the IP control group. The data center contains a series of routers and switches to route traffic between the server from the outside world. Redundant Internet connection, often by two or more service providers to provide (see multihoming). Some of the data center server for internal users need to run the basic organization of the Internet and corporate network services, such as e-mail server, proxy server, and DNS server. Network security elements are also often be configured: for example, firewalls, VPN gateways, intrusion detection systems. Network and applications monitoring system. Additional non-workplace monitoring system is also very typical to prevent the data center internal communication failure.