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We are about to start wiring out a building expansion and our vendor has laid out the racks in the following configuration:

Option 1

1U Fiber patch panel 
2U Cable Manager 
2U 48 port Patch Panel
2U Cable Manager 
2U 48 port Patch Panel
2U Cable Manager 
1U 48 port Switch
2U Cable Manager 
1U 48 port Switch
Total = 15U 

All the patch panels would be connected to the switches with 1ft+ cables fed through cable management.


What I am considering instead is:

Option 2

1U Fiber patch panel 
1U 24 port Patch Panel 
1U 48 port Switch
2U 48 port Patch Panel 
1U 48 port Switch
2U 48 port Patch Panel 
Total = 8U

All of the patch panels would be connected to the switches with .5 ft cables directly on their face with the top 24 ports of each switch patched to the patch panel above it and the bottom 24 ports of each switch patched to the patch panel beneath it which would not require any cable management.


If I go with option 2 it save all of the space used by cable management and allows us to keep adding on switches and patch panels at the end without having to re-cable all of the patch panels above.

Our vendor has indicated that this is not best practice and that .5ft cables will introduce cross talk. I could understand that being the case if we were connecting the .5 ft cable directly into another switch but we are connecting it to a patch panel that likely has another 150 ft cable run from the back of the patch panel out to the port in the building in which case the real resulting cable is 150.5 ft at minimum before even connecting it to a PC.

It seems like it makes much more sense to go with option 2. It is easier to expand, saves space, and saves money on cabling and cable management.

Does this kind of configuration make sense or is there a legitimate reason to choose Option 1 over Option 2?

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1  
neatpatch.com - It'll change your life. –  Evan Anderson Dec 31 '11 at 19:12

6 Answers 6

up vote 6 down vote accepted

Cables are easier to trace, and space is used much more efficiently in Option 2. Crosstalk increases when longer cables are tightly bundled, so you should have LESS with the short ones, even if they were switch-to-switch.

Ensure cables at back of patch panel are routed to leave room for easy switch insertion. It works well for us.

My only question: will you need more switchports for the 24-port patch panel?

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+1 - nothing like having to force 96 Cat5 cables that have almost no slack on them out of the way to get a new switch in behind them, which usually involves positining the switch vertically, forcing it through, then rotating and then screwing into place, usually chipping away the plastic outer sheet over one or two cables in the process. –  Mark Henderson Feb 22 '11 at 23:02

We do it this way (ie your option 2) in our server room and wiring centres. Much neater to setup, and if you need to pull or replace a switch, you don't have to wade through bundles of Cat5.

It's a win for us.

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I think your plan is as sensible as any. You're saving money and saving almost half of the rack space with your design.

I don't get how the vendor thinks that 6 inch cables will introduce any more cross-talk than cables of other lengths will or by jamming them all into cable managers?

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In the early days I used to go with option 1 but now prefer option 2. Either can be made perfectly tidy and manageable, if you just take the time to make it so.

One tip I would suggest, which has saved me tremendous amounts of time over the years, is to set up an easy to use and easy to maintain system for keeping track of cable endpoints. While this might not sound too important when dealing with just a rack, it should be part of a larger system. Quite simply, I use a database to record cable endpoints. I don't need to trace cables (if the database has been properly maintained) because by knowing one end of any given cable I can quickly look up where the opposite end terminates.

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try racktables - very easy to setup and well worth having - especially if you plan on any growth. –  Glenn Kelley Feb 23 '11 at 5:55

I disagree with most of you guys .. I think that some form of cable management is very worthwhile. My perspective is primarily from a consulting, having visited hundreds of sites, fixing problems and dealing with changes.

Option 2 will look great on day 1, but has no flexibility. Murphy will come looking for you, and make your life miserable. Your successor will curse your penny pinching.

IMHO, there is an element of laziness in the option 2 approach. Just put it all together and plug it it .. don't worry about tomorrow! Save a few bucks! Organizing things properly, considering future changes, and keeping things tidy and looking sharp takes time and effort.

** Future maintenance should be a primary consideration. Things change. Your installation needs to allow you to quickly and easily identify what is where, and move things around easily.

** You want to be able to easily see the front of the equipment. You want someone to be able to take a picture or put a web cam in front of the rack. You want to be able to read the labels and markings.

** The 1:1 patch-to-port matching sounds good but doesn't work in real life.
- Some switches have the ports clustered to one side or another of the switch.
- Switch ports fail.
- Things change. Switches get upgrades, specific users need specific connections, etc. - Actual ports in use don't usually distribute evenly. - Switches need to be connected to each other, which requires ports.

** You don't mention a UPS/battery backup. You need to worry about the back side of the rack as well.

** Why are you concerned about rack units? Are you leasing by the U? The cost differential between 2-post racks of various heights is trivial. Cable management things are over-priced but don't matter in the overall cost of the project. If you have physical space, I recommend a full height rack!

** I suggest leaving space at the top of the rack for another patch panel. Execs are moving walls and changing floor plans all of the time. If you leave space, then adding a few desks is a minor annoyance, not a lost weekend.

** At the very least, keep some cable management around the fiber.

** Other notes

.. use velcro straps rather than zip ties and don't wrap tightly. You should easily be able to slide a finger into a bundle.

.. get appropriately sized patch (and power) cables. Long cables that have to get coiled, tucked or stuffed somewhere contribute to big problems later.

.. My understanding is that cables < 1m are not technically within the CAT5/6 spec, but work fine for standard applications. I avoid them between switches or for connecting servers.

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I am agreeing 100% here with tomjedrz. My company provides network management services to several companies and we always see the same thing. Over time option 2 gets harder to handle.

And another point you have to look at: air flow. If you have so many cables just in front of the switch then it could be that the switches can not suck enough cold air. Or the hot air can not leave fast enough. In short your switches could get defective faster. (This all depends on the type of switches of course.)

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