CAT6 maximum length

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This topic contains 36 replies, has 6 voices, and was last updated by Profile photo of GCumbee GCumbee 4 years, 9 months ago.

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  • #56366
    Profile photo of GCumbee
    GCumbee
    Participant

    I know there has been discussion before regarding cable lengths but all I found was for 5e. Maybe I didn’t dig deep enough. I have an installation with QU32/AB168 coming up. Large auditorium. Long distance from control room to stage. Having to use existing large conduits. Looks on paper like run could well exceed 300′ maybe pushing 400’with stage reel.

    What I have always gone by is the 100-120m protocol. But will 6 gain you more distance? It does in other things I’ve done like HDMI extenders.

    Thoughts on this?

    #56367
    Profile photo of Andreas
    Andreas
    Moderator

    The ~100m number is a limitation for copper ethernet (physical delay running a bit from sender to receiver) for proper packet collision detection, using Cat6 does not change this.
    However, the native dSnake connection is full duplex and does not need to handle collisions at all, so maybe longer distances are possible. This highly depends on electrical losses through the cable and design of transmitter and receiver circuits.
    However, I personally won’t push the spec four times and either go for fiber or add some switches as repeaters.
    I guess Bob will chime in soon… 😉

    #56369
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    😉

    I THINK (need to go and check) that Cat6 is shorter limits than cat5 due to more twisting…

    Back in a mo – interesting question 😉

    Nope – they are all the same, must be something else I can’t recall which is a more twisted pair (and therefore the cable length is longer per “ground metre”

    100 metres is the limit between active nodes – so if you are out past 300′ I’d bung a simple ethernet switch in the middle.

    If you want WiFi access as well then either read up on vlans or use a second cable 😉

    I read in one location (and now I’ve lost it, although it’s alluded to above) that the limit was due to the signalling speed, and the requirement not to have a whole packet ‘on the wire’ at one time. I suspect that might only have ever been an issue in collision domains though. I do know that I have run >100m 10Mb/s over crudely patched* Cat3 – but that was switched at one end.

    * The ends went into old telephone connectors – a 2″ long PCB with four traces which plugged into a socket. So that lot was all completely untwisted 😮

    Personally…
    I’d use it as an opportunity to get a set of three VLAN switches (one at each end to handle dSnake/Control, the other as a spare/extender).
    Obviously they are billable…

    #56375
    Profile photo of PEJ
    PEJ
    Participant

    The Ethernet limit for utp (unshielded twisted pair) is 100m no matter which cable you choose. That is 328 feet. Go over the limit and you will see issues.
    The Category of the wire impacts the speed it can handle. Cat 5 and 5a can handle 10, 100, 1000Mbps. Cat6 can go higher…sort of, and has better noise/interference immunity at the slower speeds.

    If you need 400 feet then add an active device, such as a switch, as was suggested above. Another option would be to use fibre optic cable, but that will require a media converter or switch on each end. It will certainly exceed your 400 foot requirement.

    Peter

    #56377
    Profile photo of GCumbee
    GCumbee
    Participant

    Yeah. Was afraid of that. I recently had to replace a 5e run with 6 to solve and HDMI extender issue so wasn’t sure it was a distance or bandwidth issue. Putting 6 in fixed it.

    This is a large room. The conduit route is just long. I don’t have much choice. What we ran is shielded CAT 6 but as mentioned I think I’m going to be at 350ish maybe.
    Not sure where I can insert a switch that I can get power. Maybe near the end of the 300′ leg. Then rest is 100’Jackreel with Ethercons. I can and was planning on shortening it. That only really need about 50′ to hit the AB168.

    In one post Nicola said max 120m but recommended 100. If it would work to 120m I can do it.

    Nicola?

    #56378
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    HDMI extenders are rarely ethernet, and the reduction in crosstalk of cat6 may well be enough to go way beyond 100m with that kind of device.

    It is highly likely to work to 120m – I can’t actually find any definitive document talking about the logic behind the limit – and collision detection is frequently mentioned (either true or just self reinforcing, I can’t tell). IF the 100m is about collision detection then you have no issue. Also note that dSnake is a 100Mb/s protocol, and Cat6 will take Gb/s to 100m. Signal degradation should be different between the data rates, so that supports the collision domain theory.

    Any PoE switches available? Or is that getting a bit fancy for the desired application?
    A simple 30-40m mains reel would probably work quite well to get power down the conduit, although it’s not ideal (since the sockets tend to be on the reel…

    #56383
    Profile photo of GCumbee
    GCumbee
    Participant

    These extenders are twisted pair RJ45 so not sure if you call that Ethernet protocol or just what it is. Changing out 5-6 fixed the problems we had.

    #56387
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    The protocol is the electrical bit – the physical cable can be used for all sorts…
    I’m kind of hoping we get cat5 wiring for lighting circuits – after all 25W of LED with built in data connectivity could be rather useful.

    LiFi, or even just sane remote control…

    #56389
    Profile photo of GCumbee
    GCumbee
    Participant

    Cat 5-6 already widely used for DMX.

    #56390
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    Not taking the power as well though…

    #56391
    Profile photo of GCumbee
    GCumbee
    Participant

    New video cameras from several companies do PTZ plus POE on single CAT. Saves on local power supplies for cameras.

    I have some HD video installs with CAT6 running around 400′ for PTZ and works fine. They use a local power supply. So SDI/CAT6 run to camera.

    #56428
    Profile photo of PEJ
    PEJ
    Participant

    Yeah. Was afraid of that. I recently had to replace a 5e run with 6 to solve and HDMI extender issue so wasn’t sure it was a distance or bandwidth issue. Putting 6 in fixed it.

    This is a large room. The conduit route is just long. I don’t have much choice. What we ran is shielded CAT 6 but as mentioned I think I’m going to be at 350ish maybe.
    Not sure where I can insert a switch that I can get power. Maybe near the end of the 300′ leg. Then rest is 100’Jackreel with Ethercons. I can and was planning on shortening it. That only really need about 50′ to hit the AB168.

    In one post Nicola said max 120m but recommended 100. If it would work to 120m I can do it.

    Nicola?

    At 350+ you will likely see errors and retransmissions which is not good for real time data from an AB168.

    Replace the long Ethercon with a basic 50′ utp jumper to keep it under 300′. Replacing broken jumper (without Ethercon connectors) as required is better than packet loss in an audio system.

    Peter

    #56436
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    I doubt the stagebox or desk ever bother with retransmission – it’s just pointless in this scenario.

    All the evidence I’ve seen suggests that the length limit is based on collision domains, which don’t exist in dSnake.

    The limit is also certainly ‘between nodes’ rather than ‘end to end’ so the 100′ reel won’t present an issue if it between active nodes.

    #56447
    Profile photo of Andreas
    Andreas
    Moderator

    Cable length only affects signal quality in our dSnake scenario. The difference is pure physical, in terms of TP symmetry, capacitiy between wires, resistance. A better cable may provide larger lengths in terms of capacitance (like Cat6 over Cat5), but the resistive parameter is fixed. So you will get a drop in signal amplitude on longer cable runs which is known in our world as Signal to Noise ratio (SN). It is up to the receiver circuit (including the PHY) to handle this (all industry standard components, no big choice there).
    Depending on your environment longer runs using a better cable may work, but reduced SN opens the doors to fail on smaller electrical influences.
    I’d probably just try it (using a shielded Cat6 or even Cat7 cable). If it does not work reliably, splice the cable wherever a switch could be easily mounted.

    #56451
    Profile photo of GCumbee
    GCumbee
    Participant

    Its going to be a couple weeks or more before I test this. Just started on this install. Haven’t ordered the QU32/AB168 yet. Mon we continue on our quest to get the wire through a maze of concrete block walls and conduit to its destination. I think there is a point above a dressing room I can insert a switch if I have to. Not sure about power there. There is a chance I might be able to re route it through a mechanical room and shorten the run. Not use the empty conduit we were planning on. If that works I maybe can shorten it by 20-30′ or so. Anything at this point would help.

    I will report back on this when we get it going. Might wind up being last week of June. Thanks for all your input.

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