Network Diagrams

It has been said that a picture is worth a thousand words, and diagrams can speak volumes about systems. The trick is not with the tools, but with first knowing what you want to say.

Map of the server rooms is a vague objective.

Physical layout - this would begin with an accurate diagram of the server room showing such things as wall and door placement, electrical service box and outlets, and air plenumns. On this you would add the equipment racks to scale and then list the servers in each rack. A second series of diagrams would show each rack from a front and rear view with the servers and other equipment shown in the proper place within each rack. If your drawing tool has equipment templates you could use these to show the various boards and connections in the rack diagrams. To this you might want to add color coding to quickly illustrate the particular electrical circuit or UPS that each is attached to, perhaps by coloring the power supply modules. Another use of color could be to illustrate department ownership or support, or system.

Wiring schematic - this is a map of the physical cable interconnections. It does not have to be to scale since it is intended to show how the cables between devices. Devices can be shown as simple boxes. A good cable labeling system adds value, since the schematic can then reference the cabel labels. Color can be used in a variety of ways. A few approaches include by cable function - colors by 10 Mb, 100 Mb, 1 Gb, T1, RS-232, etc. By function - colors by production LAN, production WAN, NMS, primary power, UPS, etc. By system - colors by Web, ERP, VoIP, NMS, etc.

Basic network diagram - this is a map of the IP or other protocol layout showing communications and interconnection. Devices may be simple icons or graphical representations of actual equipment. The interconnects are simple lines, typically with either a media or ID label. Here you can add more meaning with color. Color can be used to illustrate subnets or systems or devices, or all of these.

Performance network diagram - similar to the basic network diagram, it adds a visual representation of the interconnections capacity and latency. The pipe diameter illustrates capacity, with a 100 Mb ethernet "pipe" being ten times the cross sectional area of a 10 Mb ethernet "pipe" for example. The length of the pipe between devices shows the latency. Apply a scale to begin with and then use it throughout. Consider using a "transparent" pipe of a fixed length for local interconnects with a latency below 1 msec. For WAN or MAN connectivity use a scale of n cm per x msec. What this provides is an easy understanding of why the site connected over a frame relay with a latency of 130 msec performs slower than the site on an equal bandwidth dedicated circuit with only 10 msec latency. For capacity planning, the pipes can be shaded to show traffic. This adds understanding as well when you are trying to decide if performance will improve by moving that 100 Mb connection with 20% utilization to a 1 Gb connection where utilization will drop below 1%.

As for tools - all of this can be done even using the draw package in Word. However, Visio 2000 Enterprize has a discovery package that will find your devices and possibly identify them by make and model. This is a real time saver. It also will do the basic network diagram aspect. Excel can be used as a text file to record the data.

When I've had the same task several times. I just do a simple search for network Diagramming and usually find a scanner, I think NetIQ makes one, that will scan your network and create a VISIO diagram. A little touch up labelling and you're done,NODES, IP's and all.