a Queueing system has 5 generators(sources) that send messages(packets) to one server. the server takes sometime (exponential distribution of inter-packet-time) then sends the packet to the sink that discards them. While the server is still processing a packet, if it receives another packet then it sends it to a QUEUE that its depth is decided by a parameter.
some statistics are needed. thats the basic idea...some other details will postponed to save time. if u know how to do the above the rest is simple(counters here and there to keep track of things within the system)
let me know if you can do it.