We had this question for a Sql Server licensing scenario recently.
The Sql Server licensing model for most organizations is derived from the Microsoft volume licensing model.
External connector licenses are also called EC licenses or Internet Connector licenses.
An EC license is required when you have users external to your organization that need to access to any Microsoft application server (such as Sql Server) and the application server was licensed originally using a (Server + Client Access) license model . An EC license is NOT required when the application server is licensed using a per-processor based license.
|External Connector license is required when you license the the server software using a CAL model.||External connector licenses are not required when you license using a per processor licensing model|
CAL licenses (from Microsoft Volume Licensing): http://www.microsoft.com/licensing/about-licensing/client-access-license.aspx
SQL Server 2005 licensing and Internet Connector License: http://www.microsoft.com/sqlserver/2005/en/us/pricing-licensing-faq.aspx
Q. What exactly is a processor license and how does it work?
….. In addition to the installation rights to the actual server software, processor licenses also grant any number of devices or users the right to access and use the server software running on those processors. These access rights are available to all devices or users, regardless of whether they are inside the organization (intranet scenarios) or outside the organization (intranet or extranet scenarios). The processor license contains all that you need. With a processor license, there is no need to purchase separate server licenses, CALs, or Internet connector licenses.
(this information is for the most part also valid for Sql Server 2008)
SQL Server 2008 Licensing Information: http://www.microsoft.com/sqlserver/2008/en/us/licensing-faq.aspx