House pre-wired for LAN network and testing line not making sense

Question

When we bought our house I had the builder pre-wire the house with Cat5e (or so I thought). The cables terminate to wall plates and I have a really simple patch bay in a closet. Of course they did not label the patch bay, so I have had to use my tester. I am noticing only 1 2 3 and 6 are lighting up on the tester. The cables I am using to test light up 1 to 8. I tried several rooms and they all register 1 2 3 and 6. Could the pairs be messed up in the cables? Is this not Cat5e? Connections do work and I am seeing gigabit connectivity on my NICs.

Update and possible answer

After some reading 1-2-3-6 are standard Ethernet. Seems most electricians only wire 2 pairs for Tx and RX.

This was confusing, because my own wiring was testing with 1-8 blinking. I wanted to make sure I didn't have to rewire my entire house.

Answer 1

Wikipedia's article for Fast Ethernet, section called "100base-TX" says, this “runs over two wire-pairs inside a category 5 or above cable. Like 10BASE-T, the active pairs in a standard connection are terminated on pins 1, 2, 3 and 6.”

Most Cat5e cable I've come across has all 4 pairs (8 wires) available. So what you are experiencing are some cheaply-made cables. Understand that this was a low-quality job, inferior to what has most commonly been offered. (Although having just two pairs is common enough that I've heard of such things, it is not the most common practice that I've come across. So, they've been cheap, at the expense if giving you low quality.) However, if the wires work well, then 100base-TX ought to work fine.

Wikipedia's article for Gigabit Ethernet, section called "1000Base-T" states, “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 adaptive equalization and a five-level pulse amplitude modulation (PAM-5) technique.”

Because of the cheap route that was taken, the end result is that the world's most common Gigabit implementation is not going to be available with such wires. (Gigabit needs 4 pairs / 8 wires, and recommends CAT6 or better, although CAT5e ought to generally work.)

I wanted to make sure I didn't have to rewire my entire house.

Enjoy one of these:

• Re-wiring the house
• Slow wired networking
• Using Wi-Fi ; modern/faster Wi-Fi connections may be father than older/slower wired connections. Whether this is a good option may vary depending on factors like distance/reception and airwave interference. You might find that to be cheaper than trying to rewire a house.