A method, system, and program product for a data processing system having multiple hosts which dynamically determines blocking of packets in the data processing system. A connection is established between a host and an adapter for communication with a Local Area Network. A set of parameters is established for blocking packets transmitted from the adapter to the host. The set of parameters is stored in the adapter to be used by that connection. The packets transmitted from the adapter to the host are grouped or blocked in accordance with the set of parameters for that connection. Periodically, the packets being transmitted from the adapter to the host are evaluated for determining changes in the parameters. Changes to the set of parameters are recorded in the adapter for that connection to the host. Where there are multiple connections established between the adapter and multiple hosts, a set of parameters to be used for each connection is established such that packets are blocked in accordance with a respective set of parameters for a respective one of the hosts.