Supporting iWARP Compatibility and Features for Regular Network Adapters

With several recent initiatives in the protocol offloading technology present on network adapters, the user market is now distributed amongst various technology levels including regular Ethernet network adapters, TCP Offload Engines (TOEs) and the recently introduced iWARP-capable networks. While iWARP-capable networks provide all the features provided by their predecessors (TOEs and regular Ethernet network adapters) and a new richer programming interface, they lack with respect to backward compatibility. In this aspect, two important issues need to be considered. First, not all network adapters support iWARP; thus, software compatibility for regular network adapters (which have no offloaded protocol stack) with iWARP capable network adapters needs to be achieved. Second, several applications on top of regular Ethernet as well as TOE based adapters have been written with the sockets interface; rewriting such applications using the new iWARP interface is cumbersome and impractical. Thus, it is desirable to have an interface which provides a two-fold benefit: (i) it allows existing applications to run directly without any modifications and (ii) it exposes the richer feature set of iWARP to the applications to be utilized with minimal modifications. In this paper, we design and implement a software stack to handle these issues. Specifically, (i) the software stack emulates the functionality of the iWARP stack in software to provide compatibility for regular Ethernet adapters with iWARP capable networks and (ii) it provides applications with an extended sockets interface that provides the traditional sockets functionality as well as functionality extended with the rich iWARP features