Thousands of hosts on a gigabit LAN, maybe not

Sat May 9 16:57:26 UTC 2015

The standard 48 port with 2 port uplink 1U switch is far from full depth.
You put them in the back of the rack and have the small computers in the
front. You might even turn the switches around, so the ports face inwards
into the rack. The network cables would be very short and go directly from
the mini computers (Raspberry Pi?) to the switch, all within the one unit
shelf.

Assuming a max sized rack with depth of 90 cm and the switches might be 30
cm. That leaves 60 cm to mount mini computers. That is approximately 12000
cubic cm of space per rack unit. A Raspberry PI is approximately 120 cubic
cm. So you might be able to fit 48 of them in that space. It would be a
very tight fit indeed but maybe not impossible.

As to the original question, I would have 48 computers in a subnet. This is
the correct number because you would connect each shelf switch to a top of
rack switch, and spend a few extra bucks on the ToR so that it can do layer
3 routing between shelfs.

Regards,

Baldur