In any typical Technical Architecture document, at a minimum, you specify details on how developers would connect to your application server which would in-turn connect to DB server, and these details without fail would need ports and protocols related details. This can grow as complex as the number of servers and components you have in your solution design. Hardware estimation and sizing is one other such area, but you might find sizing tools for the same which can provide an estimate based on the projections you provide for your target environment. Below are two such diagrams from a Sharepoint perspective which gives an overview of what kind of details you would require for an infra design perspective to rig your solution.
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