Satish , i think there is vast difference between by201 and by501 .Ericsson is the only company which as of my knowledge has sized down the hardware keeping redunancy in mind. Gone are the days whn u had 1 etc board,now u have an inbuild STM 1 magzine in the switch .same applies to group switch ,iog and cp. now iog comes in a magzine rather than a 2 rack .cp comes in a rack than than 2 rack. now there is a 3 1/2 inch od drive rather than 5 1/4 inch . no more tape drives.. there are lot of changes which i can’t describe.. for more details contact ericsson site..
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