IP Address

Can anyone tell me if there is a command line utility or third party tool that will scan the network and report back the IP address of all hosts connected to the network, particularly if some hosts are on a different subnet.

I have to install a new server onto a network (for a new client) which has network printers and a Cisco router installed, each being under support contracts by different people. I do not want to upset the current network setup.

Thanks

Mark Russell