What is rp-pppoe-* packages used for?

Hi, I started to study how to build OpenWRT recently. I discovered there are three packages named rp-pppoe-common/server/relay. They are documented that "this open-source product is ideal for Linux users with\ a DSL "modem" whose Internet service provider uses PPPoE". In my understanding, this means I need this package to connect to my internet servicee provider, i.e. dail up.

However, it is written in wiki that

The packages ppp , kmod-pppoe and ppp-mod-pppoe must be installed to use PPPoE.

It seems I do not need rp-pppoe-* packages to dail up. I am really confused, can you please teach me these packages are used for what purpose? Thanks.

The rp-pppoe-server package is needed to force any client trying to access the ports of the network interface managed by the PPPoE server to authenticate before being able to connect.

In short, it is used to protect access to a network interface, almost always an interface that provides an internet gateway, from unauthorized use. It can be also used to meter how much time and traffic is consumed by connecting clients when the ppp-mod-radius plugin is enabled and configured correctly.