Spanning-Tree or No Spanning-Tree, that is the question
Todays big issue on networks is Spanning-Tree and vendors focused to handle this issue with trill.
ToR (Top of Rack) installations are so popular and still some ways to handle STP instead of using Nexus and VDX like solutions to save a money.
My self i could’t imagine before connect ToR switches to core or distribution switch with aggregation, because i always connect my servers to switch like this for bw issue or NFT but one of my friend Levent OGUT who is in London and working on Junper said that aggregate your ToR switches to core/distribution switch to eliminate hugh STP process.
Very helpful idea to reduce number of STP process. This idea push you to Virtual Switching Systems like Juniper/Cisco
Another best practice from Juniper http://www.juniper.net/us/en/local/pdf/implementation-guides/8010018-en.pdf
Of course trill help to network guys to remove the STP from their networks but cost and possibilities to use STP can push you to mix the environment. The main limitation about virtual switching and aggregation is supported number of LAG by switch which you should consider about it.
PS: This post is only for advise about idea of reduce STP and do not provide a design.