Consider a group of IP routers connected by an ATM overlay network. Assume the IP routers use a distance-vector routing protocol (such as RIP). Consider also the case where each ATMswitch in the network is turned into anMPLS router (a "label-switched router), and hence it can run IP, and again, all routers use a distace-vector routing protocol. Under these conditions, what are the advantages, if any, of turning the ATMswitches into LSRs, as opposed to using an overlay network?