This post is part of a series that covers what I feel to be the main (or core) tasks that a Network Engineer is responsible for. See my Know Your Network – Introduction page for more details.

Documentation is a big subject, and can be overwhelming. So lets keep this simple. First things first…you need a document that shows all of your wide area network (WAN) circuits. This document should include the information needed to troubleshoot any issues, open tickets with the carriers when things do go wrong, and basically include all information needed to manage your network. Here is a very sanitized copy of my WAN drawing…(I removed about half of the drawing and dummied up the remaining confidential information)…

ACME_Network_Diagram (pdf)

Things to include for each circuit…

• Carrier circuit ID (also LEC ID when possible)
• Bandwidth
• IP addressing (both public and private)
• Location (remote site)
• LAN subnet(s) at remote site
• Router make/model
• Secure modem information (for those sites that have out-of-band management)

When creating the document, I would also recommend…

• Use Microsoft Visio. It is uniquely designed for this type of work, and has a number of templates and objects which will make the process easier. Also, most vendors (such as Cisco, HP, Juniper, etc) have created their own Visio objects of their hardware, and put them in files called “stencils” which you can download and add to Visio. This is VERY convenient! (Example: just Google “cisco stencils”)
• Use color!! By this, I mean do all IP addressing in red, circuit ID’s in blue, PRI circuits in black…etc. Choose your own colors, but stick with it…make it a standard.
• Create separate layers within the Visio drawing. One layer will be IP addressing, another layer Carrier circuit ID’s, and another circuit bandwidth….you get the idea. This does take time to initially setup, but once it is done, you will have a document that you can easily customize. As an example…you have a vendor meet and they request a network diagram. You don’t want to give them a drawing that shows any confidential information, so prior to printing or saving as a PDF, you can turn off certain layers, such as IP addressing and circuit ID’s. This makes sharing your network diagram both easy and secure, and you don’t have to maintain multiple documents.
• When creating host names for your network devices (routers, switches, etc) I would use a standard naming convention that has meaning. For example, look at the host names for the construction offices on my sample drawing…the first three letters are all “con” for construction. The next three letters show location (city), and then the final three characters show what the device is (rt-router, sw-switch, fw-firewall, ap-accesspoint, etc), followed by a number (1,2,3, etc) for each device, as there could be more than one at a location, such as switches.
• Include a Legend that shows all carrier contact information and drawing color definitions.
• Make it easy to read…print it out on standard tabloid paper (11″x17″). You can fold it in half for easy storage in your laptop case. Also, save as PDF and send to your smartphone and tablet.

This is one of the most important documents you will create and it will greatly aid you in managing your network. If you take your time and do it right, it will serve you well over the years, and will be easy to maintain and update.

Hope this helps…let me know what you think!