Hardware infrastructure migration is largely dependent on your current hardware and target hardware.  Let look at some common scenarios and network infrastructure components:


IBM Mainframe to Open Systems


      Moving IBM ....MIPS to core, processor speeds....one server to run database, application server (including transaction monitors),  batch processing, ETL software, messaging    software ..... 

Distributed Desktop to Browser/Server (client/server migrations)


RISC to CISC (x86)


IaaS - Private or Public Cloud


       Do you want to own the hardware infrastructure (private IaaS) or put it in the cloud (public IaaS) ?

Virtualization


Hardware Infrastructure


       Firewalls, load balancers, routers.  Network pipe