good cabling in real environments [Re: Request for submissions: messy cabling and other broken things]

Wed Dec 17 18:25:49 UTC 2003

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Pekka Savola wrote:

| On Tue, 16 Dec 2003, John Kinsella wrote:
|
|>Always liked the work my fellow coworkers at Globix used to do - I don't
|>have any shots of SJC or NYC online (too bad - a few projects I went to
|>alot of trouble on to show the rest how it should be done ;) ), but
|>here's one of our demo panels from LHR:
|>
|>http://thrashyour.com/lhr1-wiringdemo.jpg
|>
|>And yeah, most of what was under the floors in all the DCs looked like
|>that, and yeah I hear for strict cat5 regs that they shouldn't be
|>velcroed together like that.  Wire wraps were never used (only velcro),
|>bundles are laid down so that shortest is on the bottom side, longest
|>on the top.
|
|
| Now, we've seen a few pics of "good" cabling as well.
|
| However, I'm forced to ask which kind of "good cabling" is possible in
| a dynamic environment when you plug in/out, change, etc. the cables.
| This seems to invariably lead to total chaos :-).
|
| For example, consider the case of a patch panel of 200 plugs, where
| you'd have to wire cables to 20 different physical locations (where
| the switches/routers are)?  How do you manage that elegantly, at the
| patch panel side and the switch/router side?  :-)
|

One of the things we did was to not allow cabling directly to the switches
and routers.  We would always extend switch and router ports to structured
wiring infrastructure and then do patching from structured panel to
structured panel.  This would insure that clean wiring technique was
employed near the gear and that cables would not cross cards making them
inaccessible in the event of failure.  It also isolated the dynamic portion
of the wiring infrastructure to patch fields and away from user cabinets
and network gear.

| I mean, it's fine if you take 100 cables, and wire them between the
| patches and the switches (or the racks if you have the patch
| cross-connect there) in bulk, but consider the case where you have 15
| different switches (different subnets), a computer moving in/out of
| the room in a daily basis etc.  You can't just go around wiring like
| http://thrashyour.com/lhr1-wiringdemo.jpg or
| http://new.onecall.net/timages/cat5patch.jpg
|
| How do you do good cabling in dynamic, real environments? :-)
|

You also have to plan for plenty of cable management.  In our patch fields
we had cable mgmt at the top, the middle, the bottom, and the left and
right sides of each rack.  Took extra room and required extra racks, but it
helped mitigate sloppy patch jobs.  Additionally, we kept a ton of extra
patch cords of various lengths around.  We had preplanned the necessary
lengths and instituted a color coding scheme to denote different services
running through the cables.

- --
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bep

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