High density switches, by themselves, look very impressive. When they are cabled up they look one of two ways.
Or a cable management nightmare:
These switches cost a lot of money, so it makes no sense to have them looking bad. It is not just aesthetics either. Messy cabling can lead to downtime! Here is why - if the cabling is a “rat’s nest,” it is very easy to inadvertently tug too hard where you shouldn’t be tugging, causing undue stress on connectors. It also impedes airflow which can cause premature failure of the hardware itself. If one blade happens to go down, then the replacement of that blade becomes VERY difficult due to the cables strewn across that block the removal of the bad blade. Plus, it just looks bad! I think most would agree that this makes a big visual impact and is a true reflection of your team’s professionalism.
So how do you do this right?
First, don’t attempt this last second. Respect layer one and plan in advance - add cable planning to your purchasing process for the hardware.
Next is to map out where the switch is going to be in the rack, and map out the cable routing pathway. Plan for expansion and ensure you have adequate cable management channels to handle that expansion.
From there you want to break down the measurements into sections. Map this out on a piece of paper and note the individual measurements. For example, sketch the racks, the chassis with the appropriate blades in it, and note where the cable changes direction. Use a string or a flexible tape measure for this job, as that best emulates a cable. Also knowing the measurements of the switch itself, including the blades, will be very useful. You can use this information to come up with the total length of the cable from the first port of the switch to the first port of the patch panel. I would recommend that you add roughly 10% to this measurement. This can account for routing and bundling. It is best to be a little longer than to come up short!
Read Cabling Up High Density Switches in the Data Center - Part 2.