Cisco Systems SPA2102 manual Phone Adapter with Router, Networking Basics, The Use of IP Addresses

Phone Adapter with Router

If you use the Phone Adapter 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 Phone Adapter. You can get the information from your ISP.

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

A DHCP server can either be a designated PC on the network or another network device, such as the Phone Adapter. By default, the Phone Adapter’s Internet Connection Type is DHCP (obtain an IP address automatically).

The PC or network device obtaining an IP address is called the DHCP client. DHCP frees you from having to assign IP addresses manually every time a new user is added to your network.

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 a dedicated, high-speed connection type called Point to Point Protocol over Ethernet (PPPoE). PPPoE is similar to a dial-up connection, but PPPoE does not dial a phone number when establishing a connection. It also will provide the Phone Adapter with a dynamic IP address to establish a connection to the Internet.

By default, a DHCP server (on the LAN side) is enabled on the Phone Adapter. If you already have a DHCP server running on your network, 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 DHCP on the Phone Adapter, see the Router - LAN Setup section in “Chapter 5: Using the Web-based Utility.”

dynamic ip address: a temporary IP address assigned by a DHCP server.

dhcp (dynamic host configuration protocol): a protocol that lets one device on a local network, known as a DHCP server, assign temporary IP addresses to the other network devices, typically computers.

6	Chapter 2: Networking Basics
	The Use of IP Addresses

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