The VPCS can simulate up to 9 PCs. You can ping/traceroute them, or ping/traceroute the other hosts/routers from the virtual PCs when you study the Cisco routers in the Dynamips. VPCS is not the traditional PC, it is just a program running on the Linux or Windows, and only few network commands can be used in it. But VPCS can give you a big hand when you study the Cisco devices in the Dynamips. VPCS can replace the routers or VMware boxes which are used as PCs in the Dynamips network.
VPCS has developed from a simple tool to a powerful testing tool - ideal for use in simulated networks such as GNS3. The ability to send UDP and TCP "pings" makes it far more useful than a normal PC in testing ACLs , and the detailed output of ping replies and other commands (including the ability to see packet dumps) make it a must have item in the Networking Engineers toolkit. See my blog (Googel search for "vpcs tutorial") for more details on how to use this excellent application
i believe gns3........thnx