ISL's between 8510 and existing DCX switches

Hello Team,

We have an existing infrastructure of DCX switches 4 in number and are planning on ISLing them into the newly brought 8510's while taking advantage of VF's-We may have to create BS and VF's if want to use XISL's(just my thought).

Since the old DCX fabric already has its own zoning DB and we want to import it into the new switches(with VF's),should we use XISL with BS or dedicated withing a VF?

Thanks in advance..