To better manage your network, it is important for you to document your network and create a baseline of your network behavior. Network documentation and baseline is especially critical w hen troubleshooting a network and a troubleshooter need to use the information to efficiently diagnose and correct network problems. G ood network documentation will make you a more effective troubleshooter by saving you time and effort . An well established network documentation policy will also prevent you from performing the time - consuming and error-prone process of creating a network configuration from scratch every time when you need the information .

We listed the key g uidelines for creating effective network documentation as follows:

• Define your objectives: Define objectives for this documentation and only collect data relevant to your objective and do not over-do it.
• Determine the scope: Define which end systems are included in your domain of responsibility.
• Be consistent: Use consistent terminology, abbreviations, and style.
• Make the documents accessible: Store the network documentation in a location where it is readily available for you .
• Keep the documentation accurate: Update your network documentation timely when conditions and devices in the network change.

There are a few often-used network baseline documentations such as network configuration tables and topology diagrams. In addition, the network bandwidth usage baseline is also critical for you to understand your network. We will briefly overview each type of documentation and process in the following sections.

Network Configuration Table

When the configuration of your network is failing or performing suboptimally, a network configuration table will provide you with a saved configuration that should perform at an acceptable level. When creating a network configuration table for troubleshooting, you should document the following:

• The device name
• Data link layer addresses and implemented features
• Network layer addresses and implemented features
• Any important information about the physical aspects of the device

Network Configuration Table Components Related to Troubleshooting

Network Topology Diagram

A network topology diagram is a graphical map of a network. The topology diagram illustrates how each device in a network is connected, while also including the aspects of its logical architecture. Networkt opology diagrams share many of the same components as their network configuration table counterparts. The key values of a network map are:

• Know exactly where each device is physically located
• Easily identify the users, devices and applications that has a problem
• Help you systematically search each part of your network for problems

Each network device should be displayed on the diagram with consistent notation or a graphical symbol, and each logical and physical connection should be represented using a simple and appropriate symbol. At a minimum, a network topology map include s illustrations of all devices and how those devices are connected. Many topologies also include network cloud symbols , which is often employed to represent entities that are either outside of the autonomous control of your network or outside the scope of the topology diagram.

Topology Diagram Components

Although the components of a topology diagram can be restricted to a particular layer of the TCP/IP model, most often they are a combination of the most important components of several logical layers. To illustrate the important components of a network at the Internet TCP/IP layer, you might include IP addresses, subnet masks, and routing protocols.

The following is a sample network topology diagram created using LANsurveyor:

How to Baseline and Document Your Network ?

Network Bandwidth Usage Baseline

By monitoring your network over a long period, you can recognize its normal behavior. You begin to see a pattern in the traffic flow, such as which servers are typically accessed, when peak usage times occur, and which router/switch is the busiest and so on. Knowing your network well allows you to be more effective at troubleshooting problems that arise and optimize your network performance. This process is called baseline analysis.

A baseline can serve as a useful reference of network traffic during normal operation, which you can then compare to captured network traffic while you troubleshoot network problems. A baseline analysis speeds the process of isolating network problems. By running tests on a healthy network, you compile "normal" data to compare against the results that you get when your network is in trouble.

Additionally, knowing your network's background noise is helpful for you to recognize "real" data flow. For example, one evening after everyone is gone, no backups are running, and most nodes are on, analyze the traffic on your network. The traffic that you see is mostly broadcast and multicast packets. This traffic is the background noise of your network, which is the overhead of your network. If background noise is high, redesign your network to optimize its performance and lower this overhead.

Using a Good Tool for Your Network Documentation and Baseline

There are many tools available to automate the network documentation process. One of such tools to draw your network diagram automatically and keep your software and hardware documentation up-to-date is LANsurveyor (http://www.javvin.com/LANsurveyor.html). To set a baseline for network bandwidth usage, CyberGauge is an affordable and function rich product to choose. (http://www.javvin.com/CyberGauge.html).