Have you looked into the incremental additional costs associated with more fiber? Smallest that we've seen trunk fiber is 6 strands of SM fiber. When you look at pre-termed fiber with MTP/MPO connectors, it might be worthwhile to have home runs to each floor.
L2 rings IMHO seem pretty brittle. I know there are L2 ring products like Juniper BTI, which use ERPS and not strictly STP/RSTP to move blocking ports, and those seem a little better although it's mostly statically configured.

With one pair going up the stack and another coming down, what happens when a device in the middle releases some magic smoke? Do you have 2 devices at each landing?

Now that I've (maybe?) shot holes in some arguments, my personal preference, in a situation like this, would be to use passive DWDM.

With an OADM at each floor, you can easily terminate all the wavelengths at the home run location and have "dedicated" L1 paths to each floor. You could use the 2nd pair of fiber to even set up some form of link-agg if you so choose.

Another non-optimal option might also be something like GPON, although I've stayed away from that.

Passive DWDM would also give you room for expansion and you could have 10Gbe optics at each floor which would give you the full bandwidth at each landing.

Hope this helps. I'd be curious if anyone else has ever used DWDM in an intra-building scenario.

Thanks,

Abhi

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