Prashanth is right, a direct point-to-point Gigabit connection to the 3550-EMI would give better performance with what you've got. It'll run in full-duplex mode.
You can use GigaStack GBICs to do point-to-point connections, instead of 1000BASE-T or -SX GBICs. But you're limited to a maximum distance of 1 meter between units, vs. 100m of the -T GBICs or 220 to 275m of the -SX GBIC.
But you can add the 3550-EMI to the GigaStack "cascade". The in/out cascade configuration causes the Gigabit "backbone" between the switches to run at half-duplex. This isn't bad, if your traffic needs there are light to moderate. Also, it's very cost-effective. But if you need top performance, it's not the best approach -- a 3550-12G and point-to-point connections to each switch instead of GigaStacking would be ideal. Also, more expensive.
For somewhat better performance using just GigaStack GBICs, you could create two GigaStacks of two 3550-48-SMI switches each, and then connect each of those mini-stacks to a GBIC port of the 3550-EMI. Think of it as "segmenting" your GigaStack backbone.
Ultimately, what's best for you really all depends on your traffic needs, and your budget.
We are pleased to announce availability of Beta software for 16.6.3.
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looking for early feedback from customers befor...
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