Part I: To Add the Dial-Up Entry to ISA Server
Some PPPoE software (such as WinPoet) are represented by a dial up entry. To configure ISA to use this entry for internet access:
In the ISA Management interface, expand Policy Elements.
Right-click Dial-up Entries, click New, and then click Dial-up Entry.
Type a name and description, click the PPPoE dial-up entry by clicking Select, and then specify the appropriate account information (user name and password for the PPPoE connection) by clicking Set Account.
Part II: To Construct the LAT
When you construct the LAT, include only the network adapter that represents the internal local area network (LAN). The inclusion of the network adapter that is connected to the DSL modem does not prevent network access, but it does pose a security risk on the internal network.
Part III: To Configure Routing and Firewall/SecureNAT
The final step is to ensure that both Web and Firewall/Secure NAT clients are routed through the PPPoE connection.
Right-click Network Configuration, click Properties.
Click to select Use Dial-up Entry check box.
Expand Network Configuration.
Right-click, and then click Properties of any routes that you have configured that require access through the PPPoE adapter.
On the Action tab, click to select the Use dial-up entry for primary route check box.