asking about high speed networking topics

hi,

I am a first-time user for this website hope that you will help me to resolve my problems... Thanks

1. As we know the saturation throughput of 4-by-4 output-buffered switch is 1. May i know the reason why?

2. about the output-buffered swtiches, they perform better than input-buffered swtiches. WHY? and is it to say that it is perfectly good??? i think it must have some tradeoof right? may i know more about the output-buffered switches tradeoff???

Please provide me some guidelines on these topics....A million thanks to you take care and good luck