Diagramming the Network Infrastructure
Solutions in this chapter:
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Preexisting Documentation Physical Layout Logical Layout Internal Access External Access The Incident
˛ Summary ˛ Solutions Fast Track ˛ Frequently Asked Questions
112 Chapter 5 • Diagramming the Network Infrastructure
It would be great if you could approach the networkadministrator of a company, ask for the network documentation, and get an up-to-date Visio diagram with every hardware device, along with its network address. However, this will almost never happen. There are several reasons for this, including constantly changing infrastructure, high employee turnover, lack of training, and lack of investment in technology. In the off chance that documentationexists, it is likely to be out of date or inaccurate. In truth, you will most likely be creating the documentation and diagramming things yourself. Even if you are so lucky to find that single network administrator out of a thousand who maintains up-to-date Visio diagrams, you will still need to examine the network infrastructure yourself to validate that they are indeed accurate. This chapter willhelp make you aware of what devices are critical to document and what types of information should be included within your report. The twin goals in creating a network diagram are to accurately depict both: the layout of the network, including links, components, and the logical aspects to the environment; and the details of the network, such as model numbers, network addresses, host names, and soforth. At its most useful, the network diagram should be a document that allows an outsider to come in, review the diagram, and be able to physically locate any network infrastructure component and connect to its administrative interface. Consequently, this is a very powerful document, and should be protected appropriately. Even if the diagram is a veritable work of art, it should not be printed andhung on the wall of a public cubicle. Printed copies should be kept secured under lock and key and electronic copies should be stored in such a way that access is appropriately controlled.
The types of documentation you will encounter will vary from the nonexistent to the hugely elaborate. Unfortunately, most human beings prefer to live for the moment, and it is oftennot the case that all changes that were recently made are revisited for the purposes of reviewing and documenting the change. With that in mind, you will encounter the following four categories of preexisting documentation:
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No preexisting documentation Out-of-date documentation Inaccurate documentation Accurate documentation
Of the four potential documentation circumstances,this is not very common in mid-size and larger environments: There is usually some documentation, but it is either out of date or otherwise inaccurate (we’ll discuss those circumstances in more detail shortly). Aside from a very small organization that may not have seen any benefit to creating network diagrams for five or six computers, the most likely reason for no documentation is that it hasbeen deleted, either by accident or by intention. In either case, you may be able to retrieve some documentation from a backup, but this will likely put you in the situation of having out-of-date or inaccurate documentation, so don’t waste the time hunting down tapes for a restore!
Diagramming the Network Infrastructure • Chapter 5
In circumstances where absolutely nodocumentation exists, there is likely to be no one with a significant level of network knowledge to help you begin creating documentation, so the bulk of the work will have to be your own. There should, however, be someone that you can liaise with to identify locations you will need to access to inspect cabling and other hardware. This person may be a building manager or office administrator, so remember...