Lenght of ethernet cable for a router

[#1]

As I have mentioned on this forum before, I have a house in France with nominally 512k broadband service, more likely 100k if I am lucky and the local village a mile away is not using up the contention !

After ten years of suffering, the county has installed a new system called WiFi Max MiMo (Multiple In Multiple Out) for the rural areas.  It is a sort of cell system using a variety of repeaters located on church towers, water towers and whatever else they can find, as well as occasional antennae located on poles at the roadside.  (For anyone who may be interested, I am attaching a brochure but it is in French).

Now, my house is in a little valley.  The MiMo system needs line-of-sight to the village church tower where the closest repeater has been mounted.  It is well within the parameters for my house, except that the only place which is high enough to see the church tower is a tall barn in the garden which is on higher ground.  It is served by electricity already.  I am thinking of trying to install the MiMo antenna on the gable of this barn, and then running a cable to the box of tricks inside the barn which runs the service.

That obviously is not where I would want to locate my computer !  From the barn to the house there is already an underground conduit carrying the electricity supply.  What I am thinking of doing is running an ethernet cable in this conduit, with one end connected to the RJ45 on the box of tricks in the barn, and the other end to a standard WiFi router in the house.  In principle, I think that this should work.

However, the question I have is how long can an ethernet cable practically be without losing performance ?  I calculate that the cable run between the box of tricks in the barn to the WiFi router in the house would be about 70 meters in total.  Is this do-able ?

I would be grateful for any comments.

[#2]

Hi there,

As I'm sure you're aware the longer a cable the greater the length of time it would take for the signal to move down it, however we're talking a matter of fractions of a millisecond so I don't believe the difference would be perceptible.

I would advise using good quality cable like cat 6 though.

[#3]

Cat 5e & 6 are good for Gbit upto 100m, and Cat 6 is cable of 10Gbit upto 55m IIRC

[#4]

Thanks for the answers.

It may be that the engineer insists that the modem / router is located in the garage; I hope not but he may have rules / procedures to which he has to adhere.  If that were to be the case, then the ethernet cable would still run from the modem in the garage to the house where it would connect to a slave WiFi router.  That should work as I already do this in my house in England but disable DHCP on the slave router. 

However, the telephone supply will come from a dedicated VOIP RJ11 socket on the same modem / router in the garage which would need to be extended to the house telephone circuit.  Would it be possible to use one of the spare pairs in the ethernet cable for the telephone or would it interfere with the broadband ?  In other words, the cable would have an RJ45 on one pair and an RJ11 on another pair.

[#5]

I'm confused, what modem/router in the garage ? My French isn't perfect but that document you linked doesn't mention a modem/router or Voip ?

The antenna unit is powered using POE ( power over ethernet ) from the POE power supply unit. The 20m cable supplied is ( I assume) external grade and therefore you are limited to using that between the power supply and the antenna unit. From the power supply LAN connection the cable length won't be a problem as others have said.

Ahh , I've just found the throw away reference to the modem router!

Vous  pouvez  désormais  procéder  à  l’installation  de
votre  Box  Internet  (fournie  par  votre
fournisseur d’accès)

and for our non-french readers ( courtesy of google translate )

You can now install
Your Internet Box (provided by your
access provider)

I assume that's the modem/router with voip facility.

I don't see any problem ( and neither should the engineer ) with having the POE power supply in the barn ( apart from it's not weatherproof! so will need to be in some enclosure )  and a long cable from it's LAN socket to the Internet box in the house. As has been said , I would use CAT6 if possible but CAT5e shouldn't be an issue at 70m.

[#6]

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@adamwalker wrote:

....I don't believe the difference would be perceptible.

---

At 0·33 microseconds per 100 metres, probably not.  

[#7]

Thanks for the comments.  I congratulate you on your understanding of French !

Since my last posting, the parcel with all the equipment for the installer has arrived, which I have opened now.  Inside is the antenna, which is about 30 cm x 30 cm, so pretty unobtrusive, a 20 m length of what looks like external grade cable with an ethernet plug (RJ45) at each end, a power supply with two RJ45 sockets, one marked POE and the other marked LAN, and a WiFi modem / router with four ethernet ports (RJ45) and two telephone ports (RJ11).  It is badged with the ISPs name (Ozone) but looks to me like a pretty standard WiFi router.

Presumably, the modem / router could be installed in the garage (it is a proper dry garage with roller shutter door and electricity), from there the POE cable would go to the antenna on the roof and the 70 m LAN cable would go to the slave WiFi router in the house.

Would it be an acceptable alternative to buy 70m of external grade ethernet cable myself to replace the supplied 20m external grade cable, so that the MASTER modem  / router could be installed in the house instead of the garage, or would 70m of cable from the POE socket to the antenna result in too much signal loss ?  This would remove the need for a slave WiFi router.

Thanks.

[#8]

I'm not an expert, and my French is not brilliant,  but I think what you are proposing should work. But you could do it more simply. I am assuming the  "barn" and the "garage" are the same building.

The Antenna unit needs linking to the PSU/POE so that it is supplied with power. The LAN port on the PSU then gives you your broadband. So I think what you need to do is:

Install the antenna unit on the barn. Connect it using the 20M of cable supplied to the POE port on the power supply in the barn. Run an additional 70M length of cat6 cable from the LAN port of the PSU in the barn to the house and plug that into the router.

You might want to consider surge protectors on the 70M length of cable from the barn to the house. A local lightning strike can generate significant voltage differentials over that distance.

[#9]

Thanks.  That is really useful and helpful.  Yes, barn and garage are one and the same although barn is a red-herring as there is a barn next to the garage which I would not be using.  It would be the garage which is wind and watertight. It actually also has a loft which gives it more height and it is on higher ground than the house as well.

With regard to surge protectors, I will do as you say.  We do get bad storms with lightening and loose the power frequently, and I already protect my existing modem with a surge protector for that reason.

The line-of-sight to the church was obstructed by about six sweet chestnut trees at the top of the garden - until this afternoon.  It beggars belief that there were wide open spaces on either side but the line-of-sight had to go straight through the middle of the trees.  Chestnut is like a weed here and a plague as they grow everywhere.  A local farmer (aged 82) came to help me with his chain saw and did more work than me,  I cannot believe the strength of the man, 15 years my senior.  I am exhausted just from pulling large branches and massive logs into a huge pile where they will stay until winter when the farmer will come with tractor and trailer to take it all away to turn into wood pellets which heat the two houses on the farm.  So at least it is not wasted.  The last thing I need is more wood myself - I have probably got 10 years supply cut up in my barn.

Thanks again to everyone who has responded.   When everything is all up and running in hopefully a month or so when I come over here next (assuming the system has been finished on the church tower by then), I will post again to update you all.

[#10]

I promised to give an update on my new WiFi MiMo system in France after it had been installed, so here it is.  It is absolutely A!1.  The dish, which is only about 10 inches square,is attached to the top of the chimney.  There are about 10 transmitters in range on various church towers and water towers, but because my house is in a valley of its own, I can only see one of them, about four miles away - there has to be clear line of sight. This one is actually just on a pole on a hillside across another valley, but as they say "a miss is as good as a mile", well, I really mean the opposite. The point is that it can bee seen from the chimney without obstruction (just).  The result is speeds of 24 mb download and 3 mb upload. Unbelieveable.  Prior to that, it used to take three weeks to download the BBC web page, now it is instant !  As demand grows, contention rates may reduce that, but so far, so good.

The installation cost nothing.  It was supplied free by the County because our house is not served by fibre.  So access  was a publicly funded service.  The monthly rental is the same as my previous ADSL copper wire but, as the telephone also uses the same service, the copper and the associated dedicated telegraph pole is now redundant - shame France Telecom only renewed the copper last year !  The customer service experience from the new company is nothing like the usual "boff, followed by gallic shrug" service of France Telecom, meaning "You have a problem ? So what ?  So do lots of others" !  Having installed everything free, connected me and got everything working, I received an unsolicited telephone call two days later to enquire whether everything was alright !  But, how long will all this last ?  The French are renowned for non-existant customer service.

I should add that the telephone is not like usual VOIP at all.  I assume it is VOIP as it plugs into the router, but maybe it is more like cell-phone technology.  Call quality is excellent and no different at all to copper.

Of course, having at last got a good broadband service (three times faster than Plusnet in my similar rural situation in Dorset), I want to be able to use it everywhere in the house, but thick walls are a problem.  In Dorset, I have the same problem, and have installed a master and two slave WiFi routers using ethernet cable, disabling the dchp in the slave routers, to serve the long, thin house because WiFi does not pass through old very thick walls.  I have the same problem in France - old house, thick walls.  When the house was renovated, I made sure that trunking was buried in the plaster to take an ethernet network but the cable was never installed.  It would be easy enough to pull Cat5 cable through the trunking now, and then to attach slave WiFi routers in various rooms in the house.  The alternative would be to use a Homeplug with WiFi extenders instead.

So now my dilemma is which to do ?  I have two spare WiFi routers, so it would only be a matter of buying the cable.  But the Homeplug and extenders would be easier of course.  Being very old fashioned, my natural instinct is to do the job properly and install the Cat5 ethernet network, basically because I assume that the WiFi radios in the routers would give a stronger signal than the radios in the Homeplug WiFi extenders.  But maybe my assumption is completely wrong.

I would be most grateful if anyone could advise me which to do ?  Thanks.

[#11 · Accepted solution]

If you've already taken the trouble to bury conduit in the walls do it properly and run CAT5e/6.

Homeplugs are a convenient bodge at best

[#12]

If a job's worth doing, it's worth doing right! Forget the homeplugs.

[#13]

That's what I hoped you would say !  Slave routers with ethernet certainly work but I had no idea how they compare with homeplugs  So thanks again and I will go down that route.