How to add an additional ethernet jack in a room already wired?

Question

I have a router and switch in the basement and have set up ethernet jacks here and there on the first floor. During some remodeling, I had an electrician pull Cat6 cable up to my 2nd floor.

Now I wish I had a jack in a different place on that floor. I can access the attic crawl space where the current jack is and where I'd like another, but because the remodeling is long done, it would be impossible (or hugely expensive) to have another line run between the basement and the 2nd floor.

Can I split the cable at the current jack somehow? I see that some responses on SuperUser recommend using a switch, but I wonder about:

• transmission problems (bottlenecks)
• What kind of switch do I need?
• Would the switch have to have power (none in the crawl space, of course)?
• what about heat in the attic?

Wireless is already present on the 2nd floor but not always fast enough or secure enough for me.

Answer 1

Unfortunately switches or routers in tight space with bad ventilation can easily overheat, in most cases a reset helps getting it back to life again but just until the next overheating (I have seen switches doing this in cable management boxes on desks but running happily outside the boxes).

There is also a really hackish way to solve this problem if 100 Mbps speed is enough for you: the Ethernet cable has four pair of cables but up until 1 Gbps (1000base-T/TX) uses only two pairs (usually orange and green) the other two pairs can be used for an additional connection.

For this purpose there are so called Ethernet spliters (even on Instructables).

As an alternative you can directly split your cables coming from the wall too, just remember to use the correct pins and not to separate the wires in the pairs from each other. So putting two heads this way [ orange-white, orange, green-white, -, -, green, -, - ] and [ brown-white, brown, blue-white, -, - blue, - - ] on both ends should do the trick.

But note that replacing the heads could be much more complicated than replacing the splitters. On the other hand, putting as less components in the system as possible reduces the chance of a bad connection and failure.

Also see A “splitter” is plugged into a patch panel… how does this still work? thread on Server Fault.

Answer 2

If it was done properly & actually pulled through, then there should be a pull cable left in the space; otherwise you can pull 2 new cables through by sacrificing one of the existing cables & using that instead.

The trick is to always leave one more cable/string in a run than currently in use.

That will only work, of course, if the runs are large enough & it wasn't just plastered into the wall.

Edit
Failing that, yes, a 50 buck ethernet switch will allow you to add more devices hardwired nearby - though they will all share the single connection down to the cellar, that would only really be an issue if everything was pushing data around in high quantities all at the same time.

Answer 3

The device at the end of each cable needs to get traffic only for itself. The router (which contains a switch) does that by sending only the appropriate traffic to that cable. The router can use a cable as a trunk for more than one device but if you use a simple signal splitter at the end, the devices won't be able to distinguish what traffic belongs to each one. You need another switch to separate the traffic for each device.

Cat6 can carry a tremendous bandwidth. Using it as a trunk line is not an issue in terms of a bottleneck.

The switch would need power but all of this could be done inside that room. Connect the switch to the ethernet jack and an outlet. Then run a cable from from the switch to each device. If appearance matters, hide the cable in a channel fastened around the wall near the floor (if you use staples instead, use the type that contain a plastic "U" that ensures the cable won't get pinched and don't put any sharp bends in the cable).

An alternative, although probably more expensive, would be to use a powerline network adapter. Another cable from the router goes to a powerline interface that plugs into an outlet near the router. In the destination room, another interface plugs into an outlet and provides an ethernet jack for the additional device. It uses the house wiring for the connection in between.