Digital Equipment Corporation

David A Gagne

Satish L Rege

Kadangode K Ramakrishnan

In a network adapter for a host computer, the data occupancy level of a buffer memory used to store network packets is monitored, and the occupancy level is reported to the host. The buffer memory is organized as a plurality of fixed-size pages. A memory controller uses an allocation counter to track the number of pages available to store incoming data packets, and the value of the allocation counter is compared with a programmable threshold. A data word accompanies each packet delivered to the host to indicate whether the allocation count exceeds the threshold. When the buffer memory has insufficient free space to store an incoming packet, the packet is discarded. The network adapter keeps a count of the number of discarded packets. An adapter manager microprocessor, which is part of the network adapter, reports the count to the host computer on request. The adapter manager also reports the value of the allocation count and other important network adapter variables to the host computer.

System for using three different methods to report buffer memory

A method and apparatus for transferring packets of information with different attributes from a device interface to buffers in a host memory dedicated to particular attribute values or ranges of values. The apparatus consists of multiple shared data structures in the form of receive rings, each associated with memory buffers dedicated to a particular range of values for a particular packet attribute. The device interface determines which receive ring is associated with a buffer dedicated to the proper attribute value range by comparing the value of the attribute of the received packet with the values of attributes associated with the buffers of each ring. A sequencing ring is provided to store the order in which each receive ring must be accessed by the host cpu when retrieving packets. This sequencing ring ensures that the host cpu will retrieve the packets in the order in which they were received.

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Goffstown, NH, United States of America

David A Gagne