Very odd question about cat5 distance and router vs switch?



  • I have one client where they have 2 buildings linked together via a single cat5 ran underground. The topology of the network goes as such:

    Internet
    |
    Linksys SOHO router –--Switch----Computers
    ||
    Link to building across the property
    ||
    Linksys SOHO router acting as a switch (no internet port used, just ports 1 (other building) and 2 (switch))
    |
    Switch
    |
    Computers

    Yet when I do the following:

    Internet
    |
    Linksys SOHO router ----Switch----Computers
    ||
    Link to building across the property
    ||
    Switch
    |
    Computers

    I don't even get a link light on the switch. No activity at all.

    Any idea how to fix this and get the desired outcome I'm trying to do above? I'm guessing it has something to do with the distance a cat5 signal can travel.

    I am planning on replacing that linksys by the internet with a pfsense 2440. I would prefer not to buy two 2440's just to make this work.



  • maybe one of the pairs are damaged & for whatever reason the linksys doesn't care & the switch fails autoneg.

    in any case: copper is not the best idea to put between buildings. lightning strikes will destroy both ends of the equipement.



  • @heper:

    maybe one of the pairs are damaged & for whatever reason the linksys doesn't care & the switch fails autoneg.

    in any case: copper is not the best idea to put between buildings. lightning strikes will destroy both ends of the equipement.

    Oh I agree. I'd rather do fiber, but I wasn't the original IT guy in this deal :) Trying to work with what I have. The wire is definitely ghetto ran inside one of the buildings. One side is done up real nice, the other side not so much. It's ran underground via 3" PVC piping too which I'm sure some creatures might have been able to access somehow.


  • LAYER 8 Netgate

    How long is it? Find someone with a nice tester and have them test it. If it's bad, use the existing cable to pull through a new one.

    If it's longer than 100m (including patch cables, etc) you're going to find some gear works and some doesn't. In that case pull fiber. You can generally get away with runs longer than 100m in some cases but it's out-of-spec and something that manages to work today might not work tomorrow.

    And if it was me I'd pull twice what you think you need. If you need one pull two. If you need six pull twelve, etc. It shouldn't cost that much to have someone come out and pull a 12-strand multi-mode (good to 550m, cheaper optics) or single-mode (good to 10km+ depending on optics) and terminate it in a couple trays. At least if they can just pull it through the existing conduit.



  • As heper and Derelict already stated: use fiber between buildings - and not only because of distance limitations and lightning strikes.
    Do you have UTP or STP currently? With the shield of STP connected you can have ground loops as every building is grounded separately and levels between them are unlikely to be the same. What you hear as humm in audio can render data transmission useless (even though you're not reaching the 100m limit and all wire-pairs test good).



  • Once on top of all from me I fully agree to all things stated before but want to bring in one more
    option to solve this issue. If there are a distance that can be covered with WLAN, go and have a
    look at the UBNT equipment, there have WLAN APs pair that are building a WLAN bridge from
    150 MBit/s - 500 MBit/s or more if needed, that might be perhaps the best solution for you.

    • electric strike can also set one or more buildings in fire and what you want then tell your insurance?
      We was bringing them Internet might be not the best statement on this then?
    • if this cable is not really deep under the earth and in hardly winter times it can be broken (coper)
      or what is more bad it can be shorten and cut down the lines inside.
    • Cat.5(e) is able to be used over 100 meters right, but this often means 90 meters long and two times
      5 meters on top for the patch cables.

    So a very cheap LAN meter or cable tester will be at 10 € to get your hands on, I would suggest to test
    the line and then change them out or against a WLAN solution. The SG-2440 will be a nice pfSense box
    but can´t repair your cable or link and the UBNT WLAN AP pairs are the best option to go with in my eyes.

    • Ubiquiti NanoStation M5 - NSM5 - Link Set ~180 €
    • Ubiquiti NanoBeam M5 NBE-M5-16 - Link Set ~130 €
    • Ubiquiti NanoBeam M5 NBE-M5-19 - Link Set ~180 €

  • LAYER 8 Netgate

    Yup +1. If there's line-of-sight Ubiquiti can probably do this for US$500 including ready spares for each end on the shelf. Likely won't be gigabit, or 10G as if the right fiber and optics were employed, but probably good enough.


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