CAT 5 Splitter?

[Packin]

Is there such a thing? I'm talking about something similar to what one would plug into a phone jack to split the connection. I have my desktop, and now a notebook that I recently got which I may want to use simultaneously. Now that I'm thinking about it though, I probably won't be able to have the same IP for both computers. My setup is basically CAT 5 cables run throughout the house which all go to a central location where those cables are then plugged into a router which is hooked up to a cable modem. Any suggestions as to how I could use both of these computers at the same time in the same room? Or if my idea would work? Thanks.

-Packin-

 

[Lord Evermore]

There's no such thing, because you can't have two devices signalling over the same wire at the same time. When you connect a device to a NIC, or a hub port, the wires are electrically separated so that technically the two devices aren't on a common wire. You'd just end up with the two devices interfereing with each other. You could make a "splitter" by pulling out the unused wires from one connector on each end and wiring them to a separate connector, but you might have issues with interference and crosstalk and the like.

A hub or switch can be had for as little as 4 dollars if you look around.

 

[BigFatCow]

get a hub/switch.

 

[capricorn]

As said before, a small hub/switch will let you do this.

But say to yourself. Isn't it about time I attached a wireless access point to that router, get myself a wireless card for that laptop, and let myself roam free? Just a thought.

And yeah, every PC has to have it's own IP address.

-cap

 

[Packin]

Yes, a wireless setup would be nice. Do you know which brands are good or which brands are the most cost efficient? A recommendation for an access point and card for my laptop would be great. Thanks for replying.

*Edit* I will be going to college next fall so I need a wireless standard that works with all the other standards. I'm not quite sure what standard my college had but I will try to find out. Does this even matter?

-Packin-

 

[Lord Evermore]

At a minimum they'll be using 802.11b. That's actually the most likely, since that's 11Mbps theoretical and way less in real use, so it keeps the dirty pirates from sucking up as much of the school's bandwidth. They may also use 802.11a, or 802.11g. Those are both faster, but 11a didn't get much of a toehold, and 11g is relatively new and expensive. However if you get a 11g card, it will work on a 11b network, so you can have fast speeds using a 11g access point at home, and still work at school.

Any device that's identifiec as WiFi will work with 802.11b and of course any device identified as 802.11b should work. Not sure if WiFi includes 11g yet, I think it was going to be called something else like "Fast WiFi".

 

[byak]

Originally posted by: Lord Evermore
There's no such thing, because you can't have two devices signalling over the same wire at the same time.

Thats bullshit. Ever heard of the bus topology?

You can build a "hub" from a few cat5 connectors and any generic wire. It won't have the flashy lights, and it won't amplify the signal, but it will work the same otherwise.

 

[Lord Evermore]

Yes I know what a bus topology is. You might want to tone down the language.

Wires have to be crossed for send/receive, and I have never seen a "splitter" for Ethernet. If you just split a wire to go to two machines, then one machine will send on that wire and the other machine would never receive it, because it's going to the send pin on the second machine.

That's why crossover cables are used for direct connections between equal pinned ports.

 

[Macro2]

I think he must refering to the thin-net coxial spliters that typically were used in bus topology. On maybe the vampire clips they used on thicknet.

At any rate, as you know, cat ethernet is inherently a star topology and the splitter is a hub (multiport repeater) or switch (multiport bridge).
Circuits must be maintained as you suggested.

As far as transmitting on the same wire at the same time, no, but then there is multiplexing but thats another story.

 

[ScottMac]

Byak: you're wrong.

There's more to a hub than a bunch of crossover connections.

Coax, yeah sure, bus ... no problem. UTP requires the correct repeater / transceiver functions or nothing works (or nothing works properly).

Scott

 

[Lord Evermore]

I love the feeling of vindication. I don't get it often, usually I'm actually wrong.

 

[drag]

A cat5 splitter would be called a PASSIVE hub. That's what hubs do and that's all they do. I don't know if you can get a 2-port hub, or a y splitter or something,. A passive hub is just a one bunch of wires connecting all the other wires together.

A hub that has a power lead into it (99% you'll buy) simply acts as a repeater and boosts the signal. That's all hubs are and that is the definition of a hub. Those are called active hubs and 8 or more port active hubs are dirt cheap, that's why you don't see passive ones anymore.

Thats bullshit. Ever heard of the bus topology?

You can build a "hub" from a few cat5 connectors and any generic wire. It won't have the flashy lights, and it won't amplify the signal, but it will work the same otherwise.

That's exactly what a PUNCH DOWN BLOCK is for. It's a simple device that allows you to splice together a bunch of wires easily. They are commonly used to provide a patch panel for racks so that you can unplug wires in and out to make it easy to orginize. Another thing they are used for is provide wall outlets. Normally you have one wire patched to one outlet, but not nessicarally, but it's kinda ghetto otherwise.

Yes you can just tape the ends of a bunch of wires together and if you do it right it will work, but probably not all that well unless you go thru great pains to make sure that all the wires are tightly twisted right up to the point were you tape/solder them together. The main problem that you would run into is interference. The wires are twisted so that the electricty on each pair is going the oppisite direction and it creates a magnetic sheild from the twisted wires. Untwist them and you loose this sheild for the untwisted parts. Usually it's not a big deal, 10baset you can have a couple inches untwisted, 100baseT you probably only want a half inch untwisted, and 1000baseT you want absolutely as little as possible untwisted.

A trivia thing. You know what differenciates a cat5 vs cat5+ vs cat6? How tightly the wires are twisted.(other then maybe quality control on the wire's metal) The tighter the twist the more shielding effect you have, but also the more wire you use up per inch. So cat6 is more expensive because it uses up a lot more wire per foot then the generic cat5 stuff.

There's no such thing, because you can't have two devices signalling over the same wire at the same time

apperiantly you don't remember how ethernet works to well. To the devices (unless you are using a switch as a switch(properly and not a expensive hub,), a router, or a bridge) on a LAN that just operates off of a hub or a wireless hub the entire topography seems to them as one gigantic wire. Therefore ALL the devices are signalling on ALL of the wires ALL of the time. This is what is known as a collision domain.

Only one device can actually signal at a time. And it's first come first serve. If one machine is transmitting then all the machines are receiving and none of them "speak" until the first one shuts up, then they have randomized timers once they get dead silence until another one begins transmitting. If 2 or more try to transmit at the same time this is known as a collision and they both shut up and go back on random timers and then retransmit. Hopefully now they don't do it at the same time and everything works.

If you have too many computers on one line or wire (even though in reality they are on a bunch of different wires) then you get too many collisions and then bandwidth suffers. So that's what bridges and switches and routers are for. (although they don't do it the same way) Lots of places today will have a actual switch for each room that has their own private wire from the switch to the computer. That way unless a computer is talking to another computer in that same room, or is doing a broadcast, then each computer has the full bandwith on the wire to the switch. That is of course if the switch is set up like that, lots are just used as sort of a complex hub.

 

[drag]

One thing I forgot to mention. In order for one wire to connect directly into another computer you have to use a cross-over cable. You can't just put a straight thru wire to one or another, they have to swap then ends around, which adds to the complexity of the home-made hub thing. (meaning go and buy the cheapest hub you can find, it'll be easier)

 

[ScottMac]

Drag, your description of Ethernet is basiclly correct, but please find me a link that shows more than two ports of 10BASE-T in a passive device.

I've been in networking now for 20 years, give or take, and I've never seen or heard of a passive 10BASE-T device (other than a crossover cable, or a box with a crossover between two jacks).

You absolutely can do it with coax, 10BASE-2 (or add some external transceivers on a garden hose for 10BASE-5).

Codenoll actually had a passive FIBER hub for Ethernet (ended up being 10BASE-FC maybe FP... something like that .. passive 10 Meg Ethernet on fiber)

LatticeNet, 10 BASE-T and 100 Base-(anything) are, by design and specification, active devices.

There are Cat5-rated 110 punch blocks, but they are spec'd for cross-connect only (MDF-->IDF-->Device), not parallel connection.

There may be as many as two manufacturers of 66 blocks that are Cat5 rated (I know of one, from browsing the Anixter catalog). They are also strictly cross-connect ... and barely recommended for that.

Farallon (I think it was Farallon, maybe AMP) had a 10BASE-T daisy-chain product, which has gotta be one of the stupidest ideas in networking.

Somebody has a thing that'll break out the four-pair into two two-pair jacks (one device on each end of the cable) for two network connections on the same cable (also a bad idea, and out-of-spec).

Token-Ring has a (looks like passive) device (MAU) - really not passive, it gets it's operating voltage from phantom voltages on the cable from the clients.

See, for two devices (a crossover) it's no big deal, because you have a one-to-one, transmit-to-receive. If you add a third device to that, there's no passive way to get the TXs and RXs on all three devices to the right place ... you'll have created a short circuit between transmit and receive ... something that even coax-based Ethernet will not tolerate ... and 10BASE-T "fer sher" can't handle. At the very least, every time Station A transmits it's gonna sense a collision, JAM, and fall back.

I've never seen, never heard of, a passive 10BASE-T hub. I'm not saying they don't exist, but somehow over 20+ years they've escaped my attention. If you have a link, please put it up. (Thanks).

Regarding the differentiation of Cat5, 5e, 6: there's much more to it than the twists. It's not so much how MANY twists, but the number of twists per-pair, the lay of the pairs within the shealth (pair-to-pair relationships), insulative material for the wires, insulative material of the jacket, and in the case of Cat6, all of it that I've seen uses an "X" member to keep the pairs separate and spaced for the run of the cable. Every manufacturer has thier own formula for creating a UTP cable that will meet the spec, and simply twisting the wires of the pair tighter is not enough. Usually each pair has it's own twist-per-foot count, and theyare different from pair-to-pair. In some cases, the thickness of the wire's insulator can change the properties enough to improve the desired characteristic. It's all physics voodoo, but it's absolutely more than just twist count per foot.

At the termination, conductor spacing, inter-conductor dielectric, layout, body material, etc will determine the CAT rating of the connector. That's whay using a cheap, unrated connector can totally blow the spec out of the water and turn your expensive CAT 5e/Cat6 cable into "phone wire" (unrated crap).


Packin : Hubs are cheap, small switches are cheap. Do it right and save yourself a lot of headaches.


FWIW
Scott

 

[Alkali]

You'll have to buy a hub or switch.

There are such things as splitters, but trust me you dont want one, (in Cat5) they utilise the 4 unused wires to carry the second signal, and you need 2, one on each end to translate the signal back.

Multiple signals can go over one cable, but they have to be properly packeted up like a switch or router will do, splitters don't have the electronics to change packet information.

 

[drag]

Drag, your description of Ethernet is basiclly correct, but please find me a link that shows more than two ports of 10BASE-T in a passive device.

That's probably one of those things that is possible, but is just realy stupid to have. In order to have one you wouldn't be able to have use it as a repeater therefore the range of the device would be very limited since your going to add up the lengths of the wire together to make sure that you stay within the limits. I am sure that someone somewhere built one, it's one of those things that would of made sense to some poor guy before Hubs got a dime a dozen. Like the three-wheel car here in america. You know that it would work, that someone somewhere built one, but nobody in their right mind would actually buy one.

This is the Closest thing I could find. I guess you could concidure it a passive 3-port hub, but that's stretching it. I figured out a way to splice 3 wires together using a bunch of diodes and simple resistors, so I know it's possible, of course each time you add a port you have to increase the complexity by a factor of 2 and it's not pretty. You'd pretty much make it impossible after 5 wires. You sort of set them up in a triangle or star wiring pattern were each tx pair would go into each of the 2 opposing rx pair and use the diodes so that the voltage from a transmitting line going to the rx line doesn't try to backtrack into the other wire's tx pair. Then you would have to add a few resistors into the wires so that the baseline voltage signal doesn't get too high and screw things up.

At first I thought it would be easy until I remembered to whole crossover thing. That's one of the things that that I get mixed up on and it's been a while since I messed around with ethernet stuff. You'd notice that if you came to my house and realized that I accidently wired EVERY wire into my hub as a crossover. 3 crossovers = 1 crossover and 2 crossovers = a straight-thru. Of course after I figured out what I did i didn't have enough rj-45 jacks left to fix it and I had to wire the rest of them like that. (i've fixed it since then.)

 

[Lord Evermore]

That two-port device is pretty much the ONLY way it would work with any reliability and affordability. Three connections is the highest you can go before you start getting send and receive pairs mixed. Making your own device and isolating the signals is probably the stupidest thing I can imagine. Considering a hub is available for only 10 dollars or less, I can't see any reason someone would get anything like that device.

I like how that page describes the 30 dollar Y-net as the solution to a peer to peer network without buying 5 dollar crossover cables.

Alkali: hubs don't change packet information. Neither do switches. Hubs simply rebroadcast data onto the proper wires to the other ports. The electronics needed for that are needed because the "crossover" has to happen on multiple ports, rather than a single port, and actually wiring that up with the wires directly connected would be a problem. Switches do the same thing, but they also read the packets so that the retransmission only goes out to the proper port. It's still the same packets.

What it seems to come down to is, yes, there may be a very small number of devices that perform this function, but they're of limited use, very expensive, a bad idea, and nobody's ever heard of them because of the complete lack of need or desire for them in any market.

Ethernet is physically a star topology, all nodes connect to a central point. Conceptually it is a bus, but electrically it's not, at least in 99.9% of designs.

 

[drag]

Originally posted by: Lord Evermore
That two-port device is pretty much the ONLY way it would work with any reliability and affordability. Three connections is the highest you can go before you start getting send and receive pairs mixed. Making your own device and isolating the signals is probably the stupidest thing I can imagine. Considering a hub is available for only 10 dollars or less, I can't see any reason someone would get anything like that device.

I like how that page describes the 30 dollar Y-net as the solution to a peer to peer network without buying 5 dollar crossover cables.

Alkali: hubs don't change packet information. Neither do switches. Hubs simply rebroadcast data onto the proper wires to the other ports. The electronics needed for that are needed because the "crossover" has to happen on multiple ports, rather than a single port, and actually wiring that up with the wires directly connected would be a problem. Switches do the same thing, but they also read the packets so that the retransmission only goes out to the proper port. It's still the same packets.

What it seems to come down to is, yes, there may be a very small number of devices that perform this function, but they're of limited use, very expensive, a bad idea, and nobody's ever heard of them because of the complete lack of need or desire for them in any market.

Ethernet is physically a star topology, all nodes connect to a central point. Conceptually it is a bus, but electrically it's not, at least in 99.9% of designs.

Your, Right.