As mentioned earlier, the original CMU wireless model allows simulation of wireless LANs and ad-hoc networks. However in order to use the wireless model for simulations using both wired and wireless nodes we had to add certain extensions to cmu model. We call this wired-cum-wireless feature. Also SUN's MobileIP (implemented for wired nodes) was integrated into the wireless model allowing mobileIP to run over wireless mobilenodes. The following two subsections describe these two extensions to the wireless model in ns.