Tag Archives: network cabling

Another Example of How Important Wire is to Wireless

A house built on a shaky foundation cannot endure. And a WLAN built on a shaky wiring foundation likewise cannot endure, I tellya. My friends, is your foundation shaky? Is it? CHECK YOUR FOUNDATION NOW. (I happen to sell foundation-strengthening herbal supplements on the side, if you need that sort of thing…)

I’ve long been a proponent of recognizing installed UTP as a vital component in the networking ecosystem. Too many people take Layer 1 for granted, and forgivable sins of of our 10 Mbps and Fast Ethernet pasts won’t fly in a Gig world. Toolmakers like Fluke Networks sell cable certification testers that take the guesswork out of whether a given cable run can be relied on to perform as expected. Don’t use one of these testers at time of cable installation, and you are only assuming you have a good station cable.

I just had an interesting situation come up that I helped a very skilled field tech with. He was working in several different small buildings, each serviced by a Cisco Catalyst Switch and a handful of 3802 802.11ac access points. The switches and cable had been in place for years, and the APs for many months, all with no issues whatsoever.

Then, we changed out the old 3560X switches for shiny new 3650s (curse you Cisco for your bizarre fascination with part numbers so close together), and suddenly some APs weren’t working any more. Between us, we checked all switch settings, POST reports, CDP tables, logs, etc- everything you can dream up on the switch. We put the APs that weren’t working back on the old switches, and they came right up. Hmmm… thoughts turned to PoE/code bugs, but then I went a-Googlin’ before consulting TAC.

I found this document that put me on the path to righteousness. Though we weren’t having “PoE Imax Errors”, a couple of nuggets jumped out at me about our new switches.

PoE Imax

Holy guacamole- We got us a situation! But wait… THERE’S MORE!

PoE Imax2

Shazam! Which, of course, translates in Esperanto to “maybe your cable is actually kind of iffy, and all the CDP stuff that happens at the milliwatt level before PoE gets delivered worked OK with your old switch but not with the new one that has the enhanced PoE controller”.

If you don’t know that the newer switch does PoE differently, you might wrongly assume that your cabling is “good” because the APs worked on it when those APs used the old switches connected to that wiring. By now, you can probably guess where I’m headed…

Our tech tested the cabling on the new-switch-problem APs and in each case found that they needed help to work with the new switch. He re-terminated and tested each, with the APs then coming up with no issues. I have no doubt that this cable was certified 10-12 years ago, but in that time a lot can happen to either end of those cables depending on the environments where they are used.

Live and learn!



Could Cabling For 802.11ac Revolutionize The Low Voltage Industry?

Caution- at first read, the following may seem a bit nutty. I’m OK with that. Let it sink in…

As I wrap another interview with a major wireless vendor, once again I hear that 11ac access points will require two Gigabit uplinks bonded as an Ether Channel to handle all of that high-rate data traffic goodness that comes with the pending WLAN standard. Let’s pause for a minute- think about the wiring now in place for your APs. Most of us have a single Gigabit (or Fast Ethernet) run to each of our APs. Which means 11ac is going to MINIMALLY force us to add another wiring run per location, or redesign the whole pricey cable thing from scratch (maybe not so big of a deal in small, modern spaces- but an absolute nightmare in large environments, historic buildings, etc.).

Bottom line- UTP (that’s 4-pair network wiring for the uninitiated) will be added for 11ac. Yes, you will be runnin’ some wire, Jack. Here’s where I want you to wander into the Land of Imagination with me.

Why just run two wires to each AP? Why not run three? If you’re running wire anyways, what the heck? I’ll bet you’re wondering what that third wire is for, huh? It’s for emergency LED lighting. Or small Crystal Eye-style CCTV cameras. Or paging/muzak speakers. Or heat detectors. Or femtocells. Or a bunch of other distributed devices that are already part of the Low Voltage landscape- except in my vision, they are now somehow integrated into the access points that are all over the place. So when you device-out a new space, you have a common cable plant and decidedly less pathway and location complexity.

How does this get done, like from the component build perspective? I don’t know- I’m not that kind of engineer, So it’s easy for me to simply envision it and let someone else say the words that poo poo the notion. In my mind, I take my new 11ac AP out of the box, I attach one of a dozen different low-voltage device modules, connect three wires,and I hang it. Back in the closet, two wires go to my Ethernet switch, and one patches off to an emergency lighting system. Or the third wire also patches into the switch on another VLAN for CCTV. Or for the fire system. Or whatever.

Yes, WLAN makers would have to get cozy with folks in other industries pretty darn quick to come up with this sort of model as 11ac rolls out and we all start planning for the new wiring runs needed for it. Heck, I’ll even give ’em until Wave 2 to get it done.

If I’m paying through the nose for new access points AND new wiring, why not get something truly practical, innovative, and cool out of it? Architects/space designers would love it- they tend to hate all of the devices that are mandatory on the walls and ceilings of business environments.

OK, maybe it is a bit nutty. At the same time… maybe there’s something to this idea.