network architecture

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This chapter explains how to create the physical presence of the LIC: the bit you can touch and see, the bit that has flashing lights and dangling cables. The virtual presence, the Internet services used by Internet clients, is created by building applications later.

The network is a group of general purpose computers and specialised data communications computers connected together.

what it is

LIC topology: plan view
The end users of the LIC (the customers) are here.
Services for Internet clients go here.
The LIC support team is here.
Internet firewall

The first thing to create is a small network architecture with a data network container and application hosts.

  • The data network container is all the network paraphernalia that lets LIC services be part of the Internet.
  • Application hosts are the objects we place in our container: the computers that run the Internet services.

The first step is planning. The design of the LIC starts with the LIC topology. This the the simple view of the LIC components. The following pages explain many things, including what a data network is, why this LIC diagram looks like the way it does and what a DMZ is.

The next step is building. The hard way to build the LIC is to get all the components, lay them in a line, start at one end and connect them all together. It won't work. It is like a composer scribbling down a new symphony without making mistakes, which is impossible. Unless you are Mozart. Which is unlikely because he died in 1791. We build several small chunks and test each one.

I build up the computers later on, starting with the home network

learning to swim

It's time to inflate your armbands and wade into the shallow end of the Internet. The stages you take to build the network are listed in this table.

LIC table: build the network
  stage description
1 build your own paddling pool The first thing to do is build a suitable home for all the physical stuff. It needs power, racks, cable trays, good security, fire prevention, a solid floor and air conditioning.
2 splash around Install the first computers. You need a few general purpose computers, a few network computers, network cables and power cables.
3 go to the municipal pool Make everything talk to each other.
4 fancy strokes Connect your fledgling LIC to the outside world.
5 high dives Install the rest of the computers.

what it isn't

Physical presence and virtual presence do not correspond to hardware and software. The physical presence is not just hardware. Lots of software is required to make the data communication happen. The applications that provide the virtrual presence, on the other hand, are only software.

where it is

Wherever you put it. In a coffee shop, in a garden shed or, to be really extreme, as a simulation in a mainframe.