A method and apparatus are provided for implementing system to system communication in a switchless non-InfiniBand (IB) compliant environment. IB architected multicast facilities are used to communicate between HCAs in a loop or string topology. Multiple HCAs in the network subscribe to a predetermined multicast address. Multicast messages sent by one HCA destined to the pre-determined multicast address are received by other HCAs in the network. Intermediate TCA hardware, per IB architected multicast support, forward the multicast messages on via hardware facilities, which do not require invocation of software facilities thereby providing performance efficiencies. The messages flow until picked up by an HCA on the network. Architected higher level IB connections, such as IB supported Reliable Connections (RCs) are established using the multicast message flow, eliminating the need for an IB Subnet Manager (SM).