rack cable length

This is probably a stupid question, but....

We've got a few racks in a colo. The racks don't have any decent cable
management (square metal holes to attach velcro to). We either order
cable too long and end up with lots of loops which get in the way (no
place to loop lots of excess really) or too short to run along the
side (which is worse). It appears others using the same racks have
figured this out, but...

Do y'all just order 10 of each size per rack in every color you need
or is there a better way to figure this out? I'm guessing something
like 24 inches + 1.75 inchex x Us) + 24 inches and round up to
standard length...?

Cables should be within 2 feet of the total distance, if you order a stack several sizes too long then add something like above/below the switch:
Slack should never be stored in the vertical, only in the horizontal.

Hi Shawn,

If you don't leave slack, you can't really pull the server out of the RU
for maintenance (hot swaps, etc). Your best choice is to purchase cable
management trays if that makes sense (Dell servers usually come with
those). Otherwise you just need to deal with the loops and whatnot the
best way you can. If your colo hardware is really random (dells, HPs,
supermicros) then it gets worse, but if your hardware is homogeneous then
you can come up with some way of attaching brackets to the side of the rack
that could help you avoid a rats nest in the back of your rack (granted you
can't find cable management trays or they are too expensive to justify the

Or you build the cable to fit the span. I must be getting old.


You must build them if you want the professional look. No way around that
- unless you want to take up rack space with some sort of cable management
wrapping system and that becomes a pain to make future changes or replace

Thank You
Bob Evans

Copper and fiber patch panels are key. This way you can control the length from the patch to the device (router, switch,server).


Justin Wilson j2sw@mtin.net
http://www.mtin.net Managed Services – xISP Solutions – Data Centers
http://www.thebrotherswisp.com Podcast about xISP topics
http://www.midwest-ix.com Peering – Transit – Internet Exchange

Yeah, I am talking about just the runs in the rack - I don't see
a(nother) patch panel helping here.

I've found that the pre-crimped cables tend to hold up better than
those you do yourself...?

I can go fairly quick once I'm on a roll but I wonder if this is the
right way to go here.

There's a "best of both worlds" version of this: buy lots of the
short-length cables (1 to 6 feet) and "cut down" longer cables where
the distance exceeds the short cables I can buy.

I typically buy 25' cables each of which turns in to a pair of shorter
cables with one manufactured and one field-terminated end. I end up
with cables that are "just right" and well organized.

Harder to do with power cables but still somewhat functional.


Ok I've got a few comments offlist too and they all seem to draw the same
conclusion - crimp your own length. Thanks all for the input.