Network Documentation – CompTIA Network+ N10-009 – 3.1

One common type of network documentation is the network map. And there are different types of network maps that you might want to create. One type is a physical network map, which shows the physical layout of the equipment, the cabling, and everything in between.

This is an example of a physical network map. It shows a connection in from the internet with the physical cable plugging in to the internet router, which can be found at 10.1.1.1. There is a physical wire connecting to the internet firewall, and then another wire connecting to the core router, which is located at 10.1.10.1. This physical connectivity continues on through the rest of the diagram, and if you were to go into this room, you could track back that cable to this equipment using this physical network map.

We can often create these network maps using third party software such as Visio, OmniGraffle, Gliffy.com, and many others. The software can be used to create physical network maps. It can also be used to create logical network maps.

Logical network maps show a higher level view of connectivity, where you’re not focused on individual interfaces and cables, but more on how the entire network is connected. This is a logical network map that shows a cloud connection in the middle and different headquarters buildings connected from different locations into that single cloud. Obviously, in the middle of all of this are a number of routers, switches, and other servers, but all of that is broadly shown as a single location in a logical network map. These might be good maps to use. If you’re planning additional locations, you can view the layout of the existing wide area network cloud and then decide where the best location might be for another installation.

And if you wanted to get into a detailed view of exactly where equipment is located and what that equipment looks like, you might want to use a rack diagram. Rack diagrams are designed to give you a physical view as if you were standing in front of that rack in the data center. It’s very common to have restricted access to the data center. So a documentation like this can be used for individuals who may not have that level of access into the building. You can then use this documentation to tell someone to stand in front of the rack, look about 3/4 of the way up on unit 14, and you’ll see the power strip.

You can even use this documentation to locate the exact rack in the data center. You might have on the documentation that this is in row three of the data center, and this is rack W. This gives us a way to provide detailed documentation for someone who may be standing in front of the rack when we may not be in the same building. So instead of telling someone to reboot a server that’s in this rack, we could specifically say, go to unit 15 in this rack and reboot that individual server.

Another useful physical piece of documentation is the cable map for your office. This will allow you to see a view of the office and exactly where the wires are installed in that facility. You’ll often see one of these diagrams in the IDF or MDF. It’s usually on the wall so that you can understand where these wires are going when they leave that closet.

This would show you where the physical wires are running, either under the floor or above the ceiling. And you can see that each drop for each one of these is numbered. This allows you to correlate the network drops out at each individual desk with the network drops that are connected to the patch panels inside of the wiring closet. These are not just useful during the installation process, but they’re also useful when troubleshooting. You can track back exactly where a wire was run inside of the building and be able to correlate that back with problems that you might be having with that particular network drop. You can also create network diagrams that combine layer one, layer two, and layer three views of the network.

Layer one would be the physical layer, layer two would be the data link layer, and layer three would be your network layer. Here’s an example of a network diagram that includes a number of switches, routers, and end stations. And we have labels here for layer one, layer two, and layer three. We can start with the layer one connection, which shows the physical interfaces for the switches and the routers where all of these wires are connecting and providing this connectivity. We can overlay, on top of that, a layer two perspective, which now includes MAC addresses for all of these different components. And if you wanted to include IP addresses, we can overlay the layer three addresses so that you know exactly what IP address is associated with which MAC address, which is also associated with each physical address.

Another important part of documentation is a need to track your assets. This means that we need to put tags or labels on every asset that we’re bringing into the organization. This would be laptops, desktops, routers, firewalls, switches, and anything else that we’re buying and installing into our network. Once we have all of these devices tagged, we can use that tag when we’re referring back to a trouble ticket or some type of problem. For example, we could say that a router in the data center that’s labeled with number 42 is the one that’s causing this particular problem.

We can also use these tags for financial purposes. We may need to track these devices over time to be able to track their depreciation. Or you may need to reference the asset tag to know when the device is purchased, which would also tell you if that device was currently still under warranty. These asset tags are usually very visible so that you can find them when you’re on the phone with someone in the support team. There might be a barcode or RFID associated with this and there might be additional information. If a third party runs across this device, they’ll know exactly who owns that particular piece of equipment.

The asset tag that’s connected to the device, the components within that device, and then the user who is using that particular device may all be combined within one single asset database. This becomes a centralized database that can be used by the asset support team, by accounting, by folks that are in the finance department, and anyone else who may need access to this data. If we need to know the physical location of a device, we can look at our asset database and see what user has been assigned to this particular component. If we then know the user’s location, then we also know the location of this particular device.

As we’ve also mentioned, we may want to use this also for warranty tracking, to be able to understand when a device was purchased and what the status is of that particular warranty. And if we’re tracking the number of devices, we can also track the software that’s running on those devices. This can be very useful if we need to determine how many licenses we need to purchase for our organization. We can determine very quickly, how many of those units we own by referencing back our asset database.

Another important piece of documentation relates to the ongoing use of IP addresses in our organization. We would commonly track these by using an IP address management or IPAM solution. This is something that can provide us with a way to plan, track, and configure the DHCP and IP address schemes that we are using throughout our company. Using IP address management, we can document what users may be using what IP addresses.

Since we often use dynamic IP addressing, it’s useful to be able to map a user with a specific IP address during a particular date and time. This might also give us the ability to identify any problems or shortages that we might have with our IP addressing configurations, and based on this information, we might need to modify IP address ranges or add additional IP addresses to our DHCP infrastructure. This gives us a way to manage all of our ipv4 and ipv6 addressing throughout our organization, all from one central console. Here’s a console from an IP address manager, showing different subnet details, statistics about the IP addresses that we’re currently using, change log entries, warning, and error logs and other details that can help us manage our IP address configuration.

If you’re working with a service provider, and most organizations are, you will need some way to verify that you’re getting the proper level of service. This is often done contractually with a service level agreement or SLA. This defines the minimum level of service required for this contract that you have with this third party organization. For example, if you’re contracting with a wide area network provider or an internet provider, you may have an expectation that you’ll be up and running 99.99% of the time. And you might want to have that level of service documented as part of this SLA.

You can use this for any type of service level. For example, you might have an SLA that your organization will have no more than four hours of an unscheduled downtime. This means that your service provider will need to have something in place to be able to bring you up and running if you happen to have an outage. They might have a process for quickly dispatching a technician. Or they might have equipment that they keep on your location that you can pull out of a box, put it in the rack, and get up and running as quickly as possible.

As we’re increasing the amount of access points and other wireless infrastructure in our organizations, we need some type of documentation to understand the impact of all of these different wireless components. For that, we will create a site survey. This will allow us to identify all of the access points that we might be using, even if they are access points that we may not be in direct control of. We can at least see the frequencies that are in use and be able to document those as part of the site survey. Once we understand all the frequencies in use, we can then document those and configure our systems to have the minimum level of interference for all of our access points.

If you’re in a building with a lot of different companies or you happen to be in a large campus where there are many different buildings owned by different organizations, you may want to perform these site surveys very often to understand exactly what the wireless infrastructure may look like. One common way to document this is with a heat map. You can walk around and use a mobile device to be able to document how the wireless signal may be propagating, depending on where you may be standing inside of your building.