Last week we talked about how to cable up high density switches in the data center. I left off with best practices for determining cable measurements.
The next step is to break the ports into logical blocks. Most switch manufacturers like Cisco and Brocade have a specific way the ports are grouped, either “6 packs” or “8 packs.” Find out the measurement of these blocks. Do the same for where the other side of the cable will be plugging into. I would always recommend that you follow TIA-942 standards, cabling within the rack to a patch panel (typically the top of the rack).
The next step is what really makes this cabling job a showpiece - the staggering! Use the dimensions you have obtained above and stagger the lengths of the cables in increments according to the switch port blocks. Your length will typically increase by “X” amount for every block. Account for staggering on the patch panel side as well. Depending on where the patch panel is mounted, it can increase or decrease as well. This is where having a hand drawn diagram with measurements is VERY helpful. At this point you should also think about labeling these cables with the appropriate port numbers or other designation that will make the install a snap.
Now that you have your measurements, you will want to get your cabling ordered. Take note of the manufacturing tolerances of the suppliers assemblies. Asking for a .25” stagger when the cables you are ordering have a tolerance of +2/-1” tolerance will not turn out how you envision it, as the lengths you receive will most likely not match at all. With that said, your measurements need not be that specific. If you are close on your staggering measurement in logical “blocks” of cabling (ex: every 12 cables the length increases 4”) then during the install you will be able to run all the cables parallel and the length will all be very close so all the cables will bundle together very nicely. CABLExpress has a dedicated team that works on projects like this every day and offers a wide array of products that is designed to make these jobs even easier. The Skinny-Trunk® Harness product line eliminates cabling bulk making cable management a no-brainer, and there are pre-engineered staggers for every switch configuration.
We also have a tutorial video about this topic, available below: