Confused by Cat5e voice and data wiring

February 23, 2009 10:30 AM

I'm trying to do all the wiring in my house in order to distribute data and voice connectivity to each of the locations to which Cat 5e is run. It's been a while since I've done wiring (last time was probably a college job maybe 15! years ago), and I've got a few questions about how to set this all up. Sorry for the length, but I wanted to be as clear as possible about my current set-up.

All the inbound and outbound wiring goes into a structured wiring enclosure from Open House, using their data termination hub.

My current set-up: my Comcast cable modem's RJ-45 output is plugged into my WRT54G, which broadcasts a G network. The WRT54G's 4 outputs go to:

an Apple Airport Extreme to broadcast an N network to faster wireless devices;

a Slingbox;

the DirecTV receiver;

and a computer at that location for playing video and music and browsing internet on the attached display.

I want to connect the 4 outbound wiring locations to the wired network. So far, I have just wired in the outbound wiring to an data termination hub, matching the colors on the wires to the colors on the hub. Then, I wired all the jacks attached to that outbound wiring using the T568A standard. All the jacks seem to work fine, and I can remove one of devices currently attached to the WRT54G and connect that output to the jack on the termination hub which corresponds to each of the outbound wires. I get connectivity at the other end of each of the wires, and things seem to work well.

Question 1: Is there a way to check that this wiring is done correctly? I get the same kinds of numbers through Speedtest that I get from wireless devices on the network and the devices wired directly to the WRT54G, but it's limited by the outbound network connection and not anywhere close to 100baseT capacity. Is there a way to verify that the wiring is done correctly, or does the fact that I have a good internet connection mean that all is good? When I finally get a decent LAN set up, I feel like I will be using much more of the "capacity" of my wiring set-up, and I'm not that sure of my skills and connections.

Question 2: What do I need to put between the WRT54G and the jacks on the Cat 5e termination hub in order to distribute the network to each remote jack? Will an simple unmanaged hub do, as long as the WRT54G is not overwhelmed by the number of different active connections? Can I use a hub at each remote jack, if I want to have multiple wired devices in each remote location? Or do I need an actual switch between the WRT54G and the Cat 5e jack connected to each remote jack? What does an unmanaged hub actually do? If the WRT54G does all the routing and switching, do I just need to physically connect the right wires at the remote jacks, so that I could just wire multiple jacks into the same wire and let the WRT54G figure it all out? Bonus question: Whether I need a hub or a switch, will I find anything to fit nicely into my Open House enclosure? Is this or this what I need?

Question 3: Eventually, I will probably want to use the Cat5e drops to provide voice to the remote jacks as well. How can I figure out what twisted pair or pairs actually carry the voice signal from the phone company? Can I determine this by looking at the network interface box? How can I pass the voice and the data for the network over the same Cat5e cable, even if the maximum data speed is slower, maybe limited to "10baseT" speeds? Which wires get wired where?

Thanks for any help you can provide to a guy who hasn't messed around with low-voltage wiring since the mid 90s!

posted by iknowizbirfmark to computers & internet (11 comments total)

Question 1: Some of 3COM's network cards have cable test functions that they can run, at least on Windows. You can also pick up a simple cable tester from any small computer shop. These come in two pieces, which you place on either end of a run. The cheap ones will simply test connectivity on all eight wires. It's an easy way to determine if you have something connected in the wrong order or not fully punched down. By the way, you used a proper punchdown tool, right? There are fancier cable testers out there but you definitely don't need them for this situation.

Question 2: Start referring to them as switches. If you can actually still buy hubs avoid them in favor of switches. Switches learn what is connected to each port and help to prevent broadcast storms that hubs have no way of preventing. Switches on either end will allow you to split the connection.

Question 3: Check out the diagram partway down this page and look at which pins say "Unused" You can pull these pins out at either end and run them to other equipment. Insert argument about crosstalk and why you shouldn't use the unused pairs here, but it's theoretical. You can get away with it.

Above all else DO NOT use zip ties. Go to a craft or hardware store and get some velcro ties. These allow you to be super-flexible with the length you need, they're easy to install, and easy to remove. You won't end up slicing your hand or cable trying to cut zip ties off, and you won't pinch cables unnecessarily.

Lastly, don't exceed the recommended bend radius of whatever cable you choose.
posted by odinsdream at 10:51 AM on February 23

it's pretty easy to find just a run-of-the-mill 100baseTX switch. I wouldn't bother with a managed one for a small network; either of the two you linked to will work ok. you can, of course, get a rack-mount or desktop switch elsewhere too. rack-mount equipment tends to all be the same width - get out your tape measure to verify that a rackmount switch will fit into your enclosure, though.

i would run separate lines and termination blocks for phone. sure, you can use the unused pairs for now - for now is the key there. gigabit uses all 4 pairs, and it's cheap now. if you're to be streaming HD content (or just a lot of data, period) over your network, you'll probably want to upgrade to it eventually. (personally, I wouldn't bother with a 100Mbit network anymore; it's not that much more to get a Gb switch.) you can do Gb over Cat5e.
posted by mrg at 11:26 AM on February 23

The "termination hub" is just a punch-down panel. Typically you wire these straight-through pin-to-pin between the panel and the wall jacks, rather than puttting T568x in your walls, but in practice this doesn't really matter much. Use regular ethernet cables between the punch-down and the WRT, no intermediate device is necessary. Get a cable-tester if you like, they're available for a variety of prices. Maybe you can call a local cabling installer to see if they have anybody in your neighborhood you could have them drop by and test your 5 drops for $50 or something.
posted by rhizome at 11:33 AM on February 23

By the way, you used a proper punchdown tool, right?

Yes, a 110 tool on the termination hubs (as the documentation called for) and the included tool one-off proprietary tool for the jacks.

It looks like there are a lot of options for testing the quality of the wiring/connections, so I will probably get something like this. It may be overkill for this purpose, but it will probably serve me well as I stumble through more of this!

i would run separate lines and termination blocks for phone.

Wish that I could, but the drywall has been up for years, and cable fishing has been a nightmare with the audio cables, so I'm stuck with whatever I can manage over one run of Cat5e to each location. It sounds like I will be able to wire POTS over one pair along with 100Mbit over two of the other four twisted pairs and that will be the extent of what I can do with the existing wiring. I will mess with that after I get operational voice service.

On the switch/hub issue, I'll get a little rack mount switch for the wiring enclosure, probably one of the ones I linked before, and then a cheapie like this for distribution at the ends.

Thanks to everyone for all the help!
posted by iknowizbirfmark at 12:15 PM on February 23

How do I tell whether a switch is managed or unmanaged? Does "unmanaged switch" = "hub"? Will anything called a "switch" manage traffic to prevent broadcast storms?
posted by iknowizbirfmark at 12:17 PM on February 23

The cable tester you linked to looks overpriced, for what it's worth. If the tester runs on batteries and has LED lights it should be no more than $20. Otherwise you're paying for fluff. There are simple cable testers and there are complex cable testers. Simple = $20, Complex = $500+

Hubs are dumb. Switches have intelligence. Managed switches have more complex software that allow you to actually log into them and adjust behaviour. Simply avoid hubs since you can get a switch for probably the same price and get the benefits it offers. It's highly unlikely that you need a managed switch. These are generally necessary for segmenting commercial networks for security or performance reasons.
posted by odinsdream at 1:24 PM on February 23

Quick info byte on hub vs. switch:

A hub takes all the packets it receives on a port and broadcasts it to all but the source port. This is why it's called dumb. It neither knows nor cares what is connected to it.

A switch, on the other hand, knows the hardware addresses of all the devices that are directly connected to it. (It learns these over time as traffic comes into it on each port.) When it receives a data packet, it looks at the header to see where it's supposed to go and only sends it to that port. If it doesn't know where to send it, then it will broadcast it to all but the source port.
posted by pmbuko at 1:43 PM on February 23

The only cable tester you need is "ping". Ping your router continuously (with large packets if you prefer) and make sure the results are sane. Or just watch the statistics on your network connection- if you're not dropping packets, the wires are working just fine.

Caveat- 1000bt uses all four pairs so your setup will not be future proof.
posted by gjc at 6:08 PM on February 23

You can do speed tests on your LAN using iperf or a similar utility. It's not hard to use.
posted by snuffleupagus at 5:23 AM on February 24

gjc: Consider this scenario:

You run a length of cable and intend it to be straight-through. Instead, you cross one of the pairs making the run a crossover cable. This is accidental. You test the run with Ping on a laptop and everything works fine. You try another laptop and it doesn't work.

The reason? One laptop has a NIC that does auto-crossover and one does not. This problem would have easily been detected with a simple cable tester.
posted by odinsdream at 6:28 AM on February 24

How do I tell whether a switch is managed or unmanaged?

A managed switch costs about five times more, per-port, than an unmanaged one.
posted by rhizome at 2:05 PM on February 24