Conservation of Work - Queue management schemes can be distinguished whether or not they are work conserving .
Work conserving system sends the packet once the server has completed service.
Hence, the server may not be idle if there is work in a queue. Non-work conserving scheme is one where a server waits random amount of time before serving the next packet in a queue, even if packets are waiting in the queue. Integration with Different Networks Even if switches and routers manage their traffic perfectly, traffic still may not achieve performance guarantees.