Frag Infinity Tournament, Inc. - FITES LAN Party - www.fites.net

LAN Party Forums => Support Group => Started by: Czar on September 03, 2009, 07:50:16 AM

Title: This ethernet patch cable is missing wires..but works?
Post by: Czar on September 03, 2009, 07:50:16 AM
So I was at GameStop yesterday and found a 10' `universal ethernet patch cable` for $1.99. Yoink..as I needed one. Got it home, was looking it over. It states Patch Cable and all that but each end only has Orange and Green wires.  4 wires total on each side.

Looking top down with the clip on the top, I've got from left to right:

Orange/White
Orange
Green/White
Empty
Empty
Green
Empty
Empty

I plugged it in to a PC and router, and it worked. I was under the impression that you had to have all the colored cables in there for it to work and could use different layouts to make either patch or crossover cables. Are some of the colored wires not used in a patch cables? Is this one functional yet unreliable?
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: _!Rathe!_ on September 03, 2009, 09:57:47 AM
This is from Wikipedia (http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair):

A 10BASE-T or 100BASE-T node such as a PC also called MDI that transmits on pin 1 and 2 and receives on pin 3 and 6 to a network device uses a "straight-through" cable in the "MDI" wiring pattern. A straight-through cable is usually used to connect a node to its network device. In order for two network devices or two nodes to communicate with each other (such as a switch to another switch or computer to computer) a crossover cable is often required at speeds of 10 or 100 Mbit/s. If available, connections can be made with a straight-through cable by means of an "MDI-X" port, also known as an “internal crossover” or “embedded crossover” connection. Hub and switch ports with such internal crossovers are usually labelled as such, with "uplink" or “X”. For example, 3Com usually labels their ports 1X, 2X, and so on. In some cases a button is provided to allow a port to act as either a normal or an uplink port.[\i]
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: Petch on September 03, 2009, 10:09:03 AM
What Rathe tried to say, is that for 10/100 Base T (10/100) networks pairs 3 blue/white blue & 4 brown/white brown (pins 4, 5, 7, 8) aren't used. 

Pairs 3 & 4 are used for 1000Base-T though, so if you hooked that cable up to a gig network you'll see the difference over a cable that has all the wires vs your cable that only has pairs 1 & 2.

I found a more in-depth explanation for you instead of me typing everything out:  http://www.zytrax.com/tech/layer_1/cables/tech_lan.htm (http://www.zytrax.com/tech/layer_1/cables/tech_lan.htm)


Hope that explains everything for you!
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: decepticon on September 03, 2009, 10:39:28 AM
What petch said.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: Czar on September 03, 2009, 10:48:56 AM
So it`ll work for connecting my xbox to a wireless router? (dd-wrt and all that) non-gigabit network.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: decepticon on September 03, 2009, 11:38:25 AM
Yes.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: The Shoctor on September 03, 2009, 12:05:00 PM
It would prolly even work with gigabit. The thing it WON'T work for is POE. (Power Over Ethernet.)
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: _!Rathe!_ on September 03, 2009, 12:36:16 PM
It would prolly even work with gigabit. The thing it WON'T work for is POE. (Power Over Ethernet.)

It will probably work with gigabit but you won't connect at gigabit speeds.  It would downgrade the connection to a 100 base T.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: The Shoctor on September 03, 2009, 02:17:05 PM
It would prolly even work with gigabit. The thing it WON'T work for is POE. (Power Over Ethernet.)

It will probably work with gigabit but you won't connect at gigabit speeds.  It would downgrade the connection to a 100 base T.

Depends on the wire itself, not the number of them.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: Petch on September 03, 2009, 04:13:42 PM
It would prolly even work with gigabit. The thing it WON'T work for is POE. (Power Over Ethernet.)


It will probably work with gigabit but you won't connect at gigabit speeds.  It would downgrade the connection to a 100 base T.


Depends on the wire itself, not the number of them.



1000Base-T requires the use of all four pairs of wires.  It is true that when using 10/100Base-T devices that PoE utilized the extra pairs of wires, but when using 1000Base-T devices and PoE they actually share the wires, the data "rides on top" of the DC current.

From the wiki on GigE: (http://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T (http://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T))
Quote
In a departure from both 10BASE-T and 100BASE-TX, 1000BASE-T uses all four cable pairs for simultaneous transmission in both directions through the use of echo cancellation and a 5-level pulse amplitude modulation (PAM-5) technique. The symbol rate is identical to that of 100BASE-TX (125 Mbaud) and the noise immunity of the 5-level signaling is also identical to that of the 3-level signaling in 100BASE-TX, since 1000BASE-T uses 4-dimensional Trellis Coded Modulation (TCM) to achieve a 6 dB coding gain across the 4 pairs.

The data is transmitted over four copper pairs, eight bits at a time. First, eight bits of data are expanded into four 3-bit symbols through a non-trivial scrambling procedure based on a linear feedback shift register; this is similar to what is done in 100BASE-T2, but uses different parameters. The 3-bit symbols are then mapped to voltage levels which vary continuously during transmission.


Title: Re: This ethernet patch cable is missing wires..but works?
Post by: Petch on September 03, 2009, 04:32:41 PM
So it`ll work for connecting my xbox to a wireless router? (dd-wrt and all that) non-gigabit network.

Indeed.
Title: Re: This ethernet patch cable is missing wires..but works?
Post by: Czar on September 03, 2009, 10:54:40 PM
Shaweet. Got it all workin` tonight. Pwnin` noobs on SFIV.