Help me extend my LAN, please!

February 1, 2008 3:25 AM

I'm extending an wired ethernet LAN to a nearby house. I'm planning to connect a 50m patch cable to the existing bridge router, run it through an existing underground pipe to the other house where it would meet a switch and serve internet via two shorter patch cables (25m?) to two laptops in that house. Can anyone see a problem with this setup?

For example: I've read about the 100m signal interference rule, but is that rule refreshed again at my switch? i.e. whilst the total distance in cable from the bridge router is 75m, the closest I'll come to that 100m signal loss rule is the 50m run? Thanks for help!

posted by dance to computers & internet (14 comments total)

Also, crossed and straight cables - I've tested my setup using only straight cables (S.C.), so:

Bridge router > S.C. > Switch > S.C. > Laptop

and it seems to work fine?
posted by dance at 3:33 AM on February 1

Yeah, that all looks good. The 100m rule is only for a single cable, not the total length (otherwise the Internet wouldn't work.)
posted by krisjohn at 3:47 AM on February 1

See also
posted by chillmost at 3:48 AM on February 1

Be careful burying cables, even in conduit. Too much accumulated moisture can reduce the lifespan of the wiring and verifying the quality of pre-existing pipe is hard. Direct-burial cat5e isn't too expensive but I don't know how available it is pre-terminated. If you've got a crimper it's a non-issue of course.
posted by Skorgu at 4:57 AM on February 1

two things:

1.as Skorgu noted, you want "outside plant" cable.
2.you'll be subjected to lightning strikes killing your network gear unless you ground and protect both sides.
posted by machaus at 5:51 AM on February 1

1) Agreeing that 100M is the rule per segment. Some of the older network topologies had total length of network rules, but not when using 100bT.
2) Yes, ground everything.
posted by gjc at 6:13 AM on February 1

Yep, you want (and probably require for building code) plenum cable between, it's a fire hazard and toxic fumes thing. Make sure both ends of that conduit are grounded, potential difference between buildings can "knock the piss out of you". Modern stuff doesn't need switchover cables and will just work. I'd invest a bit and pull fiber.

The distance rules are from the hub days. Pop a switch in there and you're fine. You can go hella further than 100m on cat5 from a switch...
posted by zengargoyle at 6:22 AM on February 1

You might want to consider running a spare cable while you're running the original one for troubleshooting or even expansion purposes. It'll (probably) be a lot easier to run a spare now than to try to run a make a whole new run in a few years.
posted by boreddusty at 7:08 AM on February 1 [1 favorite]

Fiber, fiber, fiber. My cat5 has lasted at least 8 years? And I put it in late in the game. If I was doing anything labor intensive like burying cable or running cable through the wall, I'd run fiber now. You will thank me in 4 years when high bandwidth media applications become more ubiquitous and you aren't struggling to stream high definition content to multiple nodes.
posted by geoff. at 7:51 AM on February 1

One thing to be wary of is different earth points at each end - with a cat5 connection there might be enough potential difference between each end's 0V that you fry one or other switch. Fiber optics do not suffer from this issue.
posted by gi_wrighty at 9:11 AM on February 1

More here: http://ask.metafilter.com/57840/What-kind-of-network-cable-to-run-underground

(I knew my answer sounded familiar...)
posted by gi_wrighty at 9:12 AM on February 1

since you already have the underground pipe, leave a length of cord in there after you finish pulling the cable; that will make pulling additional / replacement cable easier a year from now.
posted by jenkinsEar at 10:27 AM on February 1

Sorry for the silly question - but just to be sure - what needs to be grounded (cable or conduit) and how do I go about doing the grounding?

Really pleased to hear that the need to differentiate between crossover and straight through doesn´t exist anymore. The reason I was so keen to use pre-terminated cable was because I am aware that it´s not so easy to do it right yourself.
posted by dance at 5:56 AM on February 2

Sorry for the silly question - but just to be sure - what needs to be grounded (cable or conduit) and how do I go about doing the grounding?

Not a silly question at all, I can't figure out what they are talking about either :)

Here is one of my previous answers to this type of question.
In which I make a mistake, I don't have any ethernet devices that are not isolated. When I double checked I learned that I was wrong about that :P
posted by Chuckles at 12:33 AM on February 3