My question is : if IBM Network Advisor can manage non IBM "Brocade" product? like HP Brocade?
I believe it will, the IBM's and HP's of this world are just reselling BNA as there own.
Thats said I've never tested that nor come acrosse a mixed environment.
Dion's right, any Brocade switch can be managed by IBM Network advisor (the same happens with the BNA versions of the other vendors). So there is no problem in doing it.