> The nice thing about this method is that it's all passive components. > > I might still rather do the switch at top with PoE in+out and VLAN per SM. > Without actually adding everything up I'd wager that the cost was about the > same....or comparable at least. The operational difference is in whether you > have more faith in the brains out in the field or more faith in the brains in > the office configuring switches. And if the building had more than 2 units > it might matter that you can add a 3rd or 4th SM this way. > > Or the ultimate lesson to take away from this: If you're running a difficult > and time consuming cable path then pull extra cables at the same time. It's > hard to get employees to look past the current job and think about how they > can help themselves in the future, but it's nice if they can. >
Very very true. In this case the wire run was not that difficult around 3 years ago. Then they remodeled the entire building. If I ever remodel/build a home or business I am thinking of running in wall micro duct to each location etc. > On 1/29/2020 12:52 AM, Forrest Christian (List Account) wrote: > > The differing twist lengths are engineered to minimize crosstalk between the > pairs. If all of them have the same number of twists per inch then you will > find that the same wires tend to be next to each other down the length of the > cable. If instead you have each of them have a different number of twists > such that over the length of the cable the amount of time each is in contact > with each other tends to be more even, reducing crosstalk. > > I suspect in some cases having two separate links running through the same > cable will hurt performance because you will get crosstalk from the other > link which you may not be able to cancel out using an echo canceller. > Probably depends on the length and specifics of the link. > > On Tue, Jan 28, 2020 at 8:33 PM Ken Hohhof <af...@kwisp.com> wrote: >> >> Each pair has a different number of twists per inch. In Cat5 and Cat5e >> cable I observe the green and orange pairs, which are the data pairs, have >> the tightest twists. I don’t remember if Cat6 is similar. This leads me to >> believe the blue and brown pairs may have inferior crosstalk performance. >> But GigE uses all 4 pairs for data, so my theory is probably wrong. I guess >> the important thing is that none of the pairs have the same number of twists. >> >> >> >> The reason I mention this is sometimes I see people assert that if you split >> a Cat5 cable into 2 as is being discussed, it will hurt the performance. >> >> >> >> From: AF <af-boun...@af.afmug.com> On Behalf Of Forrest Christian (List >> Account) >> Sent: Tuesday, January 28, 2020 5:24 PM >> To: AnimalFarm Microwave Users Group <af@af.afmug.com> >> Subject: Re: [AFMUG] Cambium POE Splitter >> >> >> >> This is actually pretty simple: >> >> >> >> Split the CAT5 into two, two pairs per radio, put the pairs on the data >> line. At the bottom use a 24V gigabit capable injector which puts the >> power on the data pairs. We have a couple at PacketFlux, Chuck makes a >> couple, and there are others available. The goal here is to get the 24V >> riding the data line along with the data. So effectively you have two >> 10/100 capable links up with power on them. >> >> >> >> At the top, you reverse the process.... get a device which will pull the >> power off of the data pairs, probably one of them from Chuck. (See >> 800-GigE-PoE as an example). Plug the cable from the bottom in the PoE >> port, then build yourself a cable for the radio which puts the extracted >> power on 4,5,7,8 and the data pins where they belong. >> >> >> >> You could also use a single midspan Gigabit PoE injector at the bottom with >> power on all 4 pairs, then remove it using a similar one at the top. Then >> your long CAT5 stays unsplit, and the splitting and PoE mess is all in a >> single cable harness. To do this you'd take two cat5 cables, and then wire >> the 1,2,3,6 pairs from each cable into a single RJ45 (putting one on 1,2,3,6 >> and the other on 4,5,7,8) which gets plugged into the non-PoE side of the >> extractor. Then the remaining 4,5,7,8 wires you'd connect to the power >> which came out of the PoE extractor at the top. The bottom harness would >> be similar but for simplicity you can just put 24V in the injector and not >> connect 4,5,7,8 on either CAT5. Now I think about this, this is what I'd >> probably do and just use a single 800-GigE-PoE top and bottom. >> >> >> >> On Tue, Jan 28, 2020 at 9:17 AM Matt <matt.mailingli...@gmail.com> wrote: >> >> I have a case where I need to power up two separate Cambium 24 volt >> SMs on rooftop but only need 100base to each. Its very difficult to >> run the second wire at this location which I need. Anyone know of way >> to split the cat5 at bottom and top to do this? Not likely but >> thought I would ask. >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> >> >> >> -- >> >> - Forrest >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > -- > - Forrest > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
