Week 33 Lesson Plan Addendum


Cabling Labeling Procedures

Cable labeling

There are two styles of cable labeling. Both styles involve the assignment of reference letters to specific rack locations of devices and or cabling. The military style of rack labeling is to assign an Alpha-numeric reference to each piece of equipment in the rack. The commercial style involves assignment an alphanumeric reference to each 2 and ¾ inches of vertical rack height.

A reference for rack locations will look something like:


The first A refers to the front of the rack. The #5 refers to the fifth device or location from the top of the rack. The second A refers to the left most position in the A5 location. The #1 refers to the first connection at that location. There can be more or less designations of the location but for our discussion here, we will limit the connection labeling to this sequence of alphanumerics.

One has to create a list of to and from for cable labeling purposes. A cable label will consists of three lines of information. The first line will consist of connectivity info for the end you are holding (what it plugs into). The second line of information on the label designates the other end of the cable (where it goes). And the third line gives the cable a reference designator such as a wire number such as W10023. Conversely, the other end of the cable will have the same label with the first and second lines reversed (obviously the ends of the cable are reversed so the label must be as well).

Usually within an existing organization, the labeling of cables has already been accomplished and you will just have to learn what someone else has already established. However, on many occasions, you as the lead technician will be asked to design and implement a cable labeling scheme both within your organization and for your customer. For example, if your customer is the federal government, there are established rules for cable labeling but they may not be followed. You will be expected as part of your daily task issues to learn and demonstrate a proficiency in the scheme that they use.

All devices in a rack are to be labeled. The next task associated with the learning of the cable labeling scheme is to maintain the records of all cabling in your organization. It is not a good idea to trace cabling through ducting or walls to find the other end of the cable. It also is a very good idea for your organization to not rely on the old geezer in the corner to remember and to tell you where the other end of the cable is located. After all, he may retire and never pass on his secrets. Remember, knowledge is power and one of the secrets that a lot of people believe makes them a little more valuable to their organization (and also a little more immune from layoff or firing) is that no one else has their knowledge and little secrets of cable labeling. You may run into opposition from the old timers for this very reason but you still need to persevere and get the data even if you have to do it yourself.

The other task we are going to become expert at is to create a drawing from a list of cable labels. As with anything in the computer world, accuracy is everything.

The other part of this task is to create the ability within yourself to not only document where all the cables go in your organization, but to create documents that reflect rack elevations, interconnectivity diagrams, cabling lists, cable labeling lists, etc.