The key difference between the X3522 and its predecessors is its queue handling:
- Predecessors of the X3522 bundle together a receive queue, transmit queue, event queue, and interrupt and call these a virtual interface (VI), They present a very large number (typically 1000s) of VIs that can be allocated to applications on demand.
- The X3522 has entirely separate receive and transmit queues that can be allocated more flexibly. They can be directed to separate event queues, and the event queues can be shared. The X3522 presents fewer queues (typically one per CPU, but with an overall limit) and applications can attach to them as required.