Point-to-point link

I need to do a quick point to point link with 2 hops but i won’t have any CMM available. Is it possible to create a sync with one master and configure the other master and 2 slaves to get the sync from it.

I have another question regarding the above mentioned point to point.
Since I have to do 2 hops i will have 2 backhaul units back to back which is the best way to connect them? I was thinking to connect the RJ12 port directly to each other to get the sync and the RJ45 port of both backhaul units to a switch via the power supply connector that comes with it. would that work?

Put both masters back to back have one set to generate sync and the other to rec from timing port. tie pins 1 and 6 of the timing port RJ11 for both masters together. and plug in both RJ45 ports to a switch. on the configuration for the downlink data lets say you have three sites A, B, C site A has a slave, site b has 2 masters, and C has a slave. If you want the same speed up as you want down just set both masters to 50% If you want a higher download than up you will have to set the A to B master downlink data to 25% and the B to C master to 75% or whatever value you decide but what i am getting at that one has to be opposite of the other

You don’t even need the Ethernet switch; the center two backhaul units can be connected back-to-back with an Ethernet crossover cable. The simplest way to do this is to make your own using a pair of RJ-45 wall jacks (without the wall plate) and a short piece of CAT5.

If I connect them back-to-back with a cross over cable how will i be able to power them?

Without a switch or hub, there will be three (3) cables:

1. BH1 to PowerSupply1
2. BH2 to PowerSupply2
3. PS1 to PS2

Make any one of the three – but only one – a crossover.

The PS1-to-PS2 cable needs female jacks at each end to connect to the PSs’ male plugs. You can buy two (2) female-to-female gender CAT5 gender changers to use with a male-to-male cable. Or you can make a female-to-female cable using a pair of wall jacks. Or, if you can find one, you can buy a gender changer that is also a crossover; but I’ve never seen one for sale.

Putting in a 4-port switch might be easier, but it creates another point of failure, and it may require a narrower operating temperature range. I know of a similar Canopy installation where the link failed on cold winter mornings. They installed a heater in the cabinet housing the Ethernet switch and the link stabilized.

Thanks a lot that really answered my question perfectly.

Now I think I have another problem because I’m afraid that the BH units aren’t going to be delivered on time. Is there a way to do this point to point link with 2 APs and 2 SMs since these are already available. If yes, how?

Yes, they’ll work the same way:

AP ------ SM+AP ------ SM

The AP to SM link distance, however, is limited to 15 miles within the software.

Depending upon distance requirements, we will often select the AP – SM paring to service remote towers as it permits us to service local customers as well. We use an Advantage AP to feed an Advantage SM for the point to point and use non-Advantage SM’s for local customers.

Teknix - My analysis says a straight-through cable would work as well, since all but the earliest modules auto-sense. Or did I miss something on pinouts in my analysis?

It is not recommended to set same-band collocated BHMs to different Downlink Data %s, like one 25% and one 75%. They will then have mismatched transmit/receive ratios and interfere with each other. At low throughput, you might get away with it and not see any effect, as 1) the interference is often when they aren’t sending or receiving anyway, so nothing gets “stepped on”, and 2) internal resends of bad fragments make it so the user sees good data, and no effect on throughput since there is plenty of “air time” for resends. However, at high attempted throughput, a mismatched transmit/receive ratio really hurts.

This is why in a same-band double-hop backhaul both links should be set to 50% Downlink Data. The two BHs in the middle (regardless of whether they are BHMs or BHSs) must be transmitting and receiving at the same time, so both links must be set to the same Downlink Data %, and the best value is 50% as it usually doesn’t make sense to have 25% in and 75% out from the central tower.

It is not recommended to collocate an SM and an AP that are operating in the same frequency band. An SM and AP are completely out of phase for transmit/receive. The collocated SM will be listening for its distant AP but get drowned out by the collocated AP, then in the rest of the transmit/receive cycle the collocated AP will be listening for distant SMs but get drowned out by the collocated SM. Collocate the two APs, or collocate the two SMs and put CMMs on the APs so the network stays synced.