I am looking for software that will act as multiple clients to test dhcp leases

I have setup a network with firewall/router/switch etc... It is for mobile deployments and I would like to test the device before putting it out in the field. I have been unable to test the device with higher amounts of connections (1000+) To ensure that there will still be traffic passing and that the dhcp servers will handle the connections.

Does anyone know of any software that will emulate 1000+ Connections and pass traffic or send packets per IP address to test this???