Method and apparatus for providing a network interface

Abstract

A network adapter includes a bypass buffer with sufficient capacity to store a packet from an upstream neighboring adapter and to store at least one additional incoming packet as a local packet is sent. The adapter also includes control logic which monitors the bypass buffer to determine whether the adapter may send local data packets. A network may be formed of such network adapters linked through counterrotating rings. If the control logic determines that the bypass buffer has sufficient storage available to avoid overflow while the adapter sends the local packet, the adapter sends the local packet. The control logic may choose to send a local packet only if there is sufficient room available within the bypass buffer to store a packet the same size as the local packet which is to be sent, thereby insuring that the bypass buffer does not overflow before the adapter can resume transmitting data from the bypass buffer. If there is not sufficient room within the adapter's bypass buffer, the adapter requests a pause in transmissions from its upstream neighbor which pause will permit the adapter to empty its bypass buffer and to then send a local packet. If the upstream neighbor cannot accommodate the pause request, it, in turn, requests a pause from its own upstream neighboring adapter, and so on, until a pause is effected and the original pause-requesting adapter can empty its bypass buffer and transmit its local packet.