Linksys QuickVPN Cisco WRVS4400N Wireless-N Gigabit Security Router with VPN A - Page 16

2 Networking and Security Basics This chapter describes networking and security basics. It includes the following sections: • "An Introduction to LANs" on page 16 • "The Use of IP Addresses" on page 17 • "The Intrusion Prevention System (IPS)" on page 19 An Introduction to LANs A router is a network device that connects two networks together. The router connects your local area network (LAN), or the group of personal computers in your home or office, to the Internet. The router processes and regulates the data that travels between these two networks. The router's Network Address Translation (NAT) technology protects your network of personal computers so users on the Internet cannot "see" your personal computers. This is how your LAN remains private. The router protects your network by inspecting the first packet coming in through the Internet port before delivery to the final destination on one of the Ethernet ports. The router inspects Internet port services like the web server, FTP server, or other Internet applications, and, if allowed, it will forward the packet to the appropriate personal computer on the LAN side. You can use multiple Cisco WRVS4400N Wireless-N Gigabit Security Routers to connect multiple LANs together. This usually applies to a medium-sized or larger company where you want to divide your network into multiple IP subnets to increase the intranet throughput and reduce the size of the IP broadcast domain and its interference. In this case, you need one WRVS4400N wireless router for each subnetwork and you can connect all the WAN ports to a second level router or switch to the Internet. Cisco WRVS4400N Wireless-N Gigabit Security Router with VPN Administration Guide 16