Linksys BEFW11S4 manual IP Addresses, Instant Wireless Series, What’s an IP Address?

Instant Wireless® Series

IP Addresses

What’s an IP Address?

IP stands for Internet Protocol. Every device on an IP-based network, includ- ing PCs, print servers, and routers, requires an IP address to identify its “loca- tion,” or address, on the network. This applies to both the WAN and LAN con- nections.

There are two ways of assigning an IP address to your network devices.

Static IP Addresses

A static IP address is a fixed IP address that you assign manually to a PC or other device on the network. Since a static IP address remains valid until you disable it, static IP addressing insures that the device assigned it will have that same IP address until you change it. Static IP addresses are commonly used with network devices such as server PCs or print servers.

If you use the Router to share your cable or DSL Internet connection, contact your ISP to find out if they have assigned a static IP address to your account. If so, you will need that static IP address when configuring the Router. You can get the information from your ISP.

Note: Since the Router is a device that connects two networks, it needs two IP addresses—one for the LAN side, and one for the WAN side. In this User Guide, you’ll see references to the “WAN IP address” and the “LAN IP address.”

Since the Router has firewall security (NAT), only the Router’s WAN IP address can be seen from the Internet.

However, even the WAN IP address can be blocked, so that the Router and network seem invisible to the Internet—This is shown in the Filters section in “Chapter 5: Using the Routers Web-Based Utility”.

Wireless Access Point Router with 4-Port Switch

Dynamic IP Addresses

A dynamic IP address is automatically assigned to a device on the network, such as PCs and print servers. These IP addresses are called “dynamic” because they are only temporarily assigned to the PC or device. After a certain time period, they expire and may change. If a PC logs on to the network (or the Internet) and its dynamic IP address has expired, the DHCP server will assign it a new dynamic IP address.

For DSL users, many ISPs may require you to log on with a user name and password to gain access to the Internet. This is called “Point to Point Protocol over Ethernet” or PPPoE. PPPoE is similar to a dial-up connection but does not have a phone number to dial into, and PPPoE is a dedicated high-speed con- nection. PPPoE also will provide the Router with a dynamic IP address to establish a connection to the Internet.

DHCP (Dynamic Host Configuration Protocol) Servers

DHCP frees you from having to assign IP addresses manually every time a new user is added to your network. PCs and other network devices using dynamic IP addressing are assigned a new IP address by a DHCP server. The PC or net- work device obtaining an IP address is called the DHCP client. The Router’s WAN port is, by default, set as a DHCP client.

DHCP servers can either be a designated PC on the network or another network device, such as the Router. By default, a DHCP server is enabled on your Router’s LAN ports. If you already have a DHCP server running on your net- work, you must disable one of the two DHCP servers. If you run more than one DHCP server on your network, you will experience network errors, such as conflicting IP addresses. To disable the Router’s DHCP function, see the DHCP section in Chapter 3: Configuring the Router.

Note: Even if you assign a static IP address to a PC, other PCs can still use DHCP’s dynamic IP addressing, as long as the static IP is not within the DHCP range of the LAN IP Address.

If the Router’s DHCP function fails to provide a dynamic IP address for any reason, please refer to Appendix A: Troubleshooting.

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