The term "typical" might not be so appropriate when talking about small ISPs. We have met a lot of network administrators and we seen a lot of small ISPs, and they all had different configurations.
The network we are going to build in this example is not specific to any provider but rather a general one. These types of networks exist in generally with a few modifications.
The network has more security breakpoints than the previous network; so we'll have more complex and complicated firewalls.
Let's take the following network as an example:
This is a small ISP that has one internet connection, an access network, a server farm, and the internal departments. This ISP uses Linux routers and servers.
The connection from the provider comes in one interface of the Linux core router. Usually, the core router should be a very stable and powerful machine because it needs to have a few network interfaces through which a significant amount of data is passed....