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Cat5 networking issues - Extending multiple connections

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Hi,

I have a 16 twisted pair cable going from one building probably 100m or so to another building with multiple computers in the second building. I used to use just 2 pairs for one connection to a single computer there but need to have multiple machines connected now. The connection seemed to drop in and out quite a lot before, so I put a 5 port switch in line with just one ethernet cable going in and then coming out. Is it pointless to connect multiple leads to the same switch or is there a way to keep each cable pairs separate up to each PC which still having a 'boost'?

I am concerned about collisions with multiple connections bottle-necking at the switches at either end, it will probably be expensive / sub-optimal to have multiple 5 port switches, one for each ethernet link.

Or how would someone else do it?


Thanks,

Jules
 

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I had a similar problem many years ago when I was an IT Manager.

We had a long run <100m but not by much and through some very harsh HF welding equipment.

I ended up doing a run of fibre optic with transceivers at each end which then went into a switch.

Never had a single problem with that setup.
 
Looking at your picture though - why are you going gigabit to 100 mbit ? If you have CAT5e cabling, you should be able to attain gigabit speed between the two sites if you have gigabit switches at each end and use all four pairs in the cable.

In fact that is how my workshop is connected to the main house - GB switch -> CAT5e -> GB switch - probably about 30-40 meters between switches.
 
I only have two pairs for each connection at the moment - but then there should be no reason why I can't use four pairs per connection and have half the number of connections going the distance and then multiply the connections with the switch(es) at either end, correct me if I'm wrong. Currently I have four phones going there each using two pairs of the sixteen, leaving effectively four connections for the network, but I think I only need two pairs so there is one connection between switches leaving the other three as redundancies if that one fails.

Is gigabit going to run over that distance though? Because it seemed to default to 10Mb sometimes when I had the distance between switches larger.

The 16 pair cable between the buildings is unitronics liycy/tp/ 16x2x0.14 if that makes a difference?

Thanks,

Jules
 
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If you want to run Gigabit over copper at distances near 100M you really need CAT6 cable - in CAT5/5e/6 cable each pair has a different twist/per inch rate and CAT6 has a plastic former to maintain seperation between the pairs. Your 16 core cable sounds more like phone cable than network cable. You mention that your Gigabit drops to 10Mbs which suggests the cable is way below spec'


You should be using fibre between buildings really.

Just run a single Gigabit fibre between the switches. It's very unlikely you need 1Gps for each computer back to the main building unless you are transferring huge amounts of data to different destinations at the other end.

We run 300 port switch stacks over 2 x 1GBs trunks (aggregated for resilience) and normal surfing/email/office apps have no performance issues. Only time we see 95% utilisation on a GBs links is backing up servers to LTO5 tape drives.

If you run switch to switch the link should be operating in full duplex mode, collisions are then non-existent and the distance restictions really come down to S/N and losses in the cable. Fibre SX Gigabit Ethernet will run at least 220M, if you use OM3 50/125uM fibre you'll get much further than that.

On fibre links we generally force the speed and duplex at both ends. Whatever you do make sure both ends are set the same.

Connecting multiple links between switches needs them to support some kind of link aggregation but for a few PC's your not likely to benefit. For one thing the traffic is balanced over multiple links based on source and destination (either MAC or IP) address and not link load. So traffic between one device and another will always use one and only one of the links.
 
I'm running 60m of CAT5/6 between buildings, from a DSL modem/switch to a remote computer. I worry that a nearby lightening strike will wipe out the network card(s) or modem due to an induced ground voltage difference between buildings. Any suggestions?
 
As above - fibre optic is the way to go.

Total isolation electrically as well as being totally immune to interference.

*Edit - or even consider wireless and directional antennas if you don't need vast bandwidth.
 
I'm running 60m of CAT5/6 between buildings, from a DSL modem/switch to a remote computer. I worry that a nearby lightening strike will wipe out the network card(s) or modem due to an induced ground voltage difference between buildings. Any suggestions?


There is no actual galvanic connection between devices (as long as you use UTP cable not STP) The RJ-45 connection feeds into a transformer, if it has PoE it's slightly different. Like this https://www.electro-tech-online.com/custompdfs/2013/01/PS-85789-001.pdf

I always specify fibre between buildings where I work, but where our Facilities dept' have got funny about the cost, like for a single link to a Portacabin, we have just put an old Ethernet switch at either end. The one into the main LAN connects over a 1M fibre patch lead - if lightning strikes it blows the cheap switches (and potenially the person using the computer in the Portacabin ;)

In practice I've only seen lightning damaged network kit twice. Once in a PC where the main LAN chip on the NIC had a hole in it, but the PC it was in continued to work once the NIC was replaced. The other took out a single port on a switch, with no visible damage and the rest of the switch continued to work. Not direct strikes though.
 
There is no actual galvanic connection between devices (as long as you use UTP cable not STP) The RJ-45 connection feeds into a transformer...
That is true up to a few kV. Above that everything is connected to everything and you hope that the NIC card is made with proper overvoltage protection so that the rest doesn´t catch fire.
 
That is true up to a few kV. Above that everything is connected to everything and you hope that the NIC card is made with proper overvoltage protection so that the rest doesn´t catch fire.

Yes absolutley, as Picbits says fibre optic is the way to do it.

MikeMI refers to ground induced voltage difference but the CAT5 cable between the buildings has no ground connection or any direct electrical connection - upto the point the lightning breaks it down of course.

I remember the days of 10Base2 thin (and 10Base5 thick) Ethernet over coax where occasionaly you'd go to a site, unplug the BNC connector from the PC and get noticable tingling because of the difference in ground potential.
 
In practice I've only seen lightning damaged network kit twice. Once in a PC where the main LAN chip on the NIC had a hole in it, but the PC it was in continued to work once the NIC was replaced. The other took out a single port on a switch, with no visible damage and the rest of the switch continued to work. Not direct strikes though.

I took out a whole network once with a Henry Vacuum cleaner ;)

We had a laser printer with a toner spill and I cleaned it up with the office hoover. Unfortunately this caused a huge static buildup and there was a large spark between the hoover and the laser printer which was still connected to the network.

One by one, each of the network ports on the switches went haywire - ranging from a few seconds to a couple of minutes. Then my office phone started ringing ......

A quick 50 mile round trip for an emergency switch purchase later and we were back up and running. The printer survived by the way.
 
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