ServiceLink Manual

Chapter 6. Installing And Configuring Your SME Server V5 with ServiceLink Software
Your server must know three additional things to communicate on the Internet:
• its own unique IP address so that Internet data packets can reach it.
• a subnet mask (also called a netmask) which looks like an IP address and allows other computers to infer your network address
from your IP address.
• the IP address of the external gateway for your server. This is the IP address of the router on your server’s external network. It
identifies the computer that your server should contact in order to exchange information with the rest of the Internet.
Normally, you would need to know this information and enter it into the server console. However, most ISPs are capable of
automatically assigning these configuration parameters to your server using a DHCP server or PPPoE.
If you have a static IP address and your ISP is configuring your server using DHCP or PPPoE, select Option 1, 2 or 3
depending upon how you will be connecting to your ISP. When you first connect to your ISP, your server will automatically be given
its external interface configuration parameters.
If your ISP is providing you with a dynamic IP address, the ISP will configure this through DHCP or PPPoE and your server will
be re-configured automatically whenever your IP address changes. If you plan to use a Dynamic DNS service, select Option 2.
Otherwise, select Option 1.
There are some very good reasons to use a dynamic DNS service if you have a dynamically assigned IP address. It is a simple,
affordable way to ensure continuity of service when your IP address changes. Please read the next section on dynamic DNS for more
information about dynamic DNS.
If you are using ADSL and need PPP over Ethernet, choose Option 3. You will then be asked for the user name and password you
use to connect to your ISP. Note that some ISPs require you to enter their domain name as well as your user name.
What is PPPoE?
PPPoE is the Point-to-Point Protocol over Ethernet. Essentially, it is an implementation of the popular PPP protocol used for
dialup connections - only configured to run over an Ethernet connection. Many ISPs that provide ADSL connections use PPPoE
as the method of connecting their customers to the Internet over ADSL.
43