L shaped building - Long run

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dkcook2-p40
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L shaped building - Long run

Postby dkcook2-p40 » Wed May 06, 2009 6:08 am

I've read the maximum length you can run an Ethernet run is roughly 300feet.

We are trying to run a line in one of our old buildings that is L shaped. The total distance is around 300 - 350 feet. About half way on the run at the corner of the L we will be stopping at a clerk's office and put in a switch. From there we will be going from under the building up to the attic and down to the other end of the building.

My question is does the 300 foot rule reset with the switch in the middle? At the end of the run we are talking about putting a wireless router to cover that side of the building and a family history room.

Any thoughts? Thanks for your help this is a great forum.

thanks, Dave

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aebrown
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Postby aebrown » Wed May 06, 2009 6:27 am

dkcook2 wrote:I've read the maximum length you can run an Ethernet run is roughly 300feet.
...
My question is does the 300 foot rule reset with the switch in the middle? At the end of the run we are talking about putting a wireless router to cover that side of the building and a family history room.


Yes, the 300 foot limit does reset at a switch, so you're just fine. A switch receives the packets and then sends them again, so you get a fresh 300 feet, so to speak.

By contrast, a passive hub is simply wiring and so the packets are not refreshed and so the limit is not reset. But you did mention a switch, so this would not apply in your case.

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Postby techgy » Wed May 06, 2009 6:58 am

Alan_Brown wrote:Yes, the 300 foot limit does reset at a switch, so you're just fine. A switch receives the packets and then sends them again, so you get a fresh 300 feet, so to speak.

By contrast, a passive hub is simply wiring and so the packets are not refreshed and so the limit is not reset. But you did mention a switch, so this would not apply in your case.


I wouldn't bet on the 300 foot limit as being firm. One ward in our stake recently had a video teleconference between the ward and 2 general authorities. The conference was transmitted over a high speed DSL line. We ran the Ethernet cable from the family history room to the chapel - a length of approximately 140 feet down the halls.

As this was a temporary installation we didn't need to make it pretty. :)

We did a test feed a couple of days prior to the conference and failed miserably. The packet loss was high and both audio/video were constantly freezing for several seconds.

We solved our particular problem by extending the phone line that supported the DSL into the chapel and then using a short Ethernet cable. This worked perfectly.

I didn't take the time to experiment with Ethernet cable lengths but I was no where near the 300 foot limit. You may want to look at a wireless installation instead of the Ethernet.
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dkcook2-p40
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Postby dkcook2-p40 » Wed May 06, 2009 9:34 am

Techgy wrote:I didn't take the time to experiment with Ethernet cable lengths but I was no where near the 300 foot limit. You may want to look at a wireless installation instead of the Ethernet.


Sounds like this was a frustrating situation.

My experience with long runs has not been the same. I have run long lengths in other buildings very successfully. I have one building that has three lines between 150 and 200 feet and another building that has a run that goes at least 150 feet under a cultural hall.

I agree wireless is a good solution and we will be installing a couple of wireless routers as part of this installation also.

Good news on the switch.

Thanks for the feedback.

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Mikerowaved
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Postby Mikerowaved » Wed May 06, 2009 11:40 am

dkcook2 wrote:My experience with long runs has not been the same. I have run long lengths in other buildings very successfully.

My experience has been the same. A good quality CAT5e (or better) cable is much better at reducing loss and rejecting interference over long runs than standard CAT5. There are higher grade cables to chose from, but CAT5e should give you the best bang for your buck. Also, make sure all of your connectors and terminations are similarly rated and (hopefully) professionally installed. These usually end up being the weakest links in most installations.

Best of luck in your project. :)
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dkcook2-p40
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Postby dkcook2-p40 » Wed Jun 10, 2009 7:21 pm

Thanks for your help with this. It worked fine. We had a network engineer help with a couple of semi - computer savvy folks and we got it set up and working well. I would also recommend it be set up professionally if possible.

We were able to cover 95% of the building with two n-routers. We ran wired lines to each clerk computer. We will be running a family history workroom (unofficial) with a couple of computers off the wireless network (WAP right above the room).

Thanks for your help. Glad to have this installed and functioning.

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Ethernet cabling

Postby billshort-p40 » Thu Jun 11, 2009 2:09 pm

Glad you were able to get your equipment working. For future reference here is some additional information. The length limit for that is part of the official Ethernet specification is 100 meters (328 feet) combined cable length. I have several runs at my work that exceed that, a couple are around 750 feet long. While this is definitely not a recommended practice, it illustrates the fact that the 100 meter limit is a conservative limit and is based on the technology limitations at the time the standard was adopted.

There are a number of factors that can impact the success of cabling installations. If you were having trouble with runs under the 100 meter limit there were definitely some of these issues involved.

Use quality cable rated at least CAT 5 and maybe CAT 5e or CAT 6 for longer runs. The way the wires are inserted into the plastic (RJ-45) connectors matters. I've found that using the standard known as T568-B gives the best results and reduces problems by providing better separation between the individual pairs at the connector. Cables should never be kinked, bent 180 degrees onto itself, or folded. Avoid compressing cables with wire ties or other methods that bind down the cables too tightly. Don't run the cables near any electrical devices or along side of an electrical cable run because it may induce electrical noise into the wire. Excessive pull force on an Ethernet cable during installation can cause enough stretching of the individual wires to affect performance. The maximum recommended pulling force is 25 ft/lbs.

Hope this information is of some help to the forum members.

Bill

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300 ft rule

Postby gdtaylor-p40 » Mon Jun 29, 2009 7:45 am

300 ft rule is more of a recommendation that depends on your signal and hardware quality. The greater your signal frequency (or bandwith being used) the better your harware needs to be to handle it effectively. Operating at or over the fringe of the recommendaton means small details of the quality of wire and connectors used, wire kinks/abrasions and equipment quality used make a bigger difference in throughput.

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Postby jdlessley » Mon Jun 29, 2009 11:44 am

gdtaylor wrote:300 ft rule is more of a recommendation that depends on your signal and hardware quality.
The most common Church network installations use Cat5, Cat5e, or Cat6 cable. The ANSI/TIA/EIA-568-B.1-2001 specifications for these cables limit the maximum distance between nodes as 100 meters (roughly 328 feet). This specification is derived from the electrical propagating properties of the copper medium used. Timing of the signal over the maximum distance is what drives this limit. Signal and hardware quality limit the maximum reliable signal frequency that can be used and not the maximum distance. Frequency translates in lay terms to the amount of data or bandwith the medium can provide. The ANSI standards are designed to account for quite a number of variables that affect the ideal situation. While an installation may be able to transmit signals on a given day at distances greater than 100 meters the reliability of the signal goes down dramatically when this distance is exceeded (signal packet collisions and packet reception/responses exceeding the maximum time). Professional installations attempt to achieve near as possible to 100% reliability. Adhering to the ANSI specifications will ensure the greatest reliability as possible.
gdtaylor wrote:The greater your signal frequency (or bandwith being used) the better your harware needs to be to handle it effectively.
This statement is true. But it has little to do with the maximum network cable run.
gdtaylor wrote:Operating at or over the fringe of the recommendaton means small details of the quality of wire and connectors used, wire kinks/abrasions and equipment quality used make a bigger difference in throughput.
Again this is incorrect because the maximun run of a network cable is limited by the timing of the signal. The quality of the signal is affected by the longer runs of cable but that factor does not come into play until well after the timing limitation is exceeded. If the ANSI standards were adjusted to allow for a longer time of signal propagation then longer cable runs with high signal reliability would be possible.

The bottom line is to not exceed the 100 meter standard for Church installations. Doing so may incure additional costs and lowered reliability.
JD Lessley
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