At the very minimum use bidirectional modules so you will have four channels. That way you would only have 15 switches on a chain. Also be sure to configured your STP weight so the cut will be in the middle. So one fiber will normally be transmitting to 7 switches, the other fiber to the other 8 switches.

This is still inferior to the WDM solutions proposed, but I fear you have multimode fiber and might not have that choice.

Regards,

Baldur

On Wed, Feb 26, 2020 at 3:33 AM Norman Jester <nj@jester.mx> wrote:

I’m in the process of choosing hardware
for a 30 story building. If anyone has experience with this I’d appreciate any tips.

There are two fiber pairs running up the building riser. I need to put a POE switch on each floor using this fiber.

The idea is to cut the fiber at each floor and insert a switch and daisy chain the switches together using one pair, and using the other pair as the failover side of the ring going back to the source so if one device fails it doesn’t take the whole string down.

The problem here is how many switches can be strung together and I would not try more than 3 to 5. This is not something I typically do (stacking switches). I have fears of STP and/or RSTP issue stacking past Ethernet switch to switch limits (if they still exist??)

Is there a device with a similar protocol as the old 3com (now HP IDF) stacking capability via fiber?

I’d like to use something inexpensive as its to power ubiquiti wifi on each floor. Ideally if you know something I don’t about ubiquiti switches that can do this I’d appreciate knowing.

Norman