When you cascade, here is the basic rule.
1) you get out of at least 3 target ports into 3 User Station ports of the secondary switch, this creates 3 pass-ways to the second switch. Should you need more then that drop 4 or 5.
2) have you mean targets on the Main switch and the secondary targets on the second tier switch.
3) also you can have 2 top tier switches interconnected and then go down one tier... you could go 2 tiers down.... but then it becomes very complicated to troubleshoot and layout the none blocking setup.
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