Patent ID: 7873751

Claim:
A computer program product stored in a computer-readable recordable-type medium comprising functional descriptive material that, when executed by a computer, causes the computer to perform actions that include: receiving a packet in a host channel adapter for a system area network, wherein the packet is received by the host channel adapter from an application on a host associated with the host channel adapter and the packet is received by the host channel adapter for the purpose of transmitting the packet over the system area network, and wherein in response to the host channel adapter's receiving the packet and in response to an associated Force Out bit in a work queue element being set to a first value, the host channel adapter attempts to transmit the packet to local logical host channel adapters, and in response to the channel adapter's receiving the packet and in response to the associated Force Out bit in the work queue element being set to a second value that is distinct from the first value, the host channel adapter transmits the packet over a system area network fabric, and wherein the host channel adapter is shared among a plurality of logical partitions within a logically partitioned data processing system, and wherein each logical partition within the plurality of logical partitions includes a logical host channel adapter having a logical port; checking a multicast table in the host channel adapter to determine if a matching entry exists in the multicast table for information in the packet, wherein the multicast table contains information on multicast groups to which logical ports of logical host channel adapters belong; and forwarding the packet to trusted software in response to a determination that the packet is intended for multicasting and that no matching entry exists in the multicast table for the information in the packet, wherein the trusted software forwards the packet to one or more appropriate recipient logical partitions within the plurality of logical partitions.