Track Physical Network Connections
November 23, 2007
If you are maintaining a computer network, here are tips that have been very helpful in my experience. Remember to always document your decisions.
Unique Cable Colors
For each network device (hub, switch, router, gateway, etc.) choose one color for cables and stick with it. For example, say you have a router, a switch, and an access point. Start at the top: router is the parent so we choose one color, say black. All child devices connected to the router will connect through black network cables. A switch is attached to the router. All child devices connected to the switch will be connected through, say, yellow cables. The switch, however, is connected through a black cable to the router, since the router is the parent device for the switch. The next thing in the network are two desktops and a wireless access point. These would be connected to the switch using yellow cables. If we had another switch (switch B) to connect to the first switch, we could use blue cables to connect child nodes to it. However, it would itself be connected to its parent using yellow cables.
If your network is big enough to repeat colors, use this rule of thumb: two parent devices with same colored cables should be physically and/or logically far apart. If they are physically far apart, you may identify devices easily. If they are physically close enough to cause confusion, use logical separation: one color is at the start and the end of the logical network. The next color is the second and the second-to-last device. The third color is the third and third-to-last device.
A variation to this is to use colors for networks instead of network devices. For example, you may have an external and internal (192.168.1.0/24) network. You can use two different colors to represent them. As number of networks increases, you use more and more colors. No matter how many network devices are involved in one network, they all use the same color. It’s the network and not the network device which is more important.
Identify Source and Destination
If you go with the color scheme mentioned above, you can quite easily identify the source node for each cable you see. However, you may not be able to identify a target without putting labels on the cables themselves. The best places to label (identify) are points of connection (parent and child ends, right before the port where the cable has been inserted), points where cables change directions (where a cable has to go around an object, for example), and where a whole bunch of cables have been tied together.
Identify Network Devices by Hierarchy
On each network device, put a label which identifies it based on the network’s logical hierarchy. In our example, we have three layers or levels: router, switch, and switch B. You could label the router as L1 (level 1), switch as L2, and switch B as L3. As the wireless access point is connected to L2 but is itself a parent of some wireless devices, it could be labeled L3 as well.
Now we have two devices at L3: switch B and wireless access point. So you could then label them as L3-N1 (node 1) and L3-N2 respectively. To be even more descriptive, you could label them L3-N1-SW (switch) and L3-N2-WAP (wireless access point).
If at L3 you had more than one switch, you could modify the labels to reflect this: L3-N1-SW1, L3-N1-SW2, and so on. This would reduce confusion if more than one similar types of devices exist at the same hierarchical level.
Using these tips you should be able to reduce confusion when looking at your network. You are able to maintain and troubleshoot with much more ease now than before. Even if you do not have documentation handy, you should be able to get an idea of the logical and physical layout of the network. Of course, these tips will help in a relatively small network. But if you breakdown your huge network into smaller logical pieces, you could manage it this way.
Some good tips have been provided, in words and/or pictures, by the following: When data center cabling becomes art;