A computer system that implements a quality of service policy. Information defining the quality of service policy is stored in a central location, such as a server within an enterprise. Policy management software on clients in the network download quality of service policy information from the central location to the clients. Within a client, a portion of the policy information is selected based on its applicability to a particular connection. The selected information is cached with an association to the connection so that, as datagrams are generated for transmission over the network, relevant policy information is quickly accessed for use in controlling transmission characteristics of datagrams sent using that connection. The policy information is applied on a datagram-by-datagram basis, allowing policy information to be selectively applied based on network type. Policy information may be selectively applied to those datagrams transmitted over a managed network.