US 7,065,582 B1 · Automatic generation of flow control frames

Abstract

An automatic flow control mechanism that supports two modes of automatic flow control is provided in a network interface. In the first flow control mode, the network interface periodically compares the number of available receive descriptors with low and high threshold values. When the number of available receive descriptors falls below the low threshold value, the network interface sends a PAUSE frame requesting the link partner to suspend its transmission (in a full-duplex mode), or enables the back pressure mechanism (in a half-duplex mode). In the second flow control mode, when the network interface detects that the number of available receive descriptors is less than the low threshold value, it transmits a PAUSE frame requesting the link partner to suspend its transmission for a time period corresponding to a preprogrammed pause value (in a full-duplex mode), or enables the back pressure mechanism, at least, for a time interval defined by a pause timer loaded with the preprogrammed pause value (in a half-duplex mode).

Claims19

Dependent claims

A computer system comprising:

a local bus,
a host processor coupled to the local bus,
a network interface for providing an interface between the local bus and a network medium, and
a memory coupled to the local bus, the memory having receive buffers allocated for receiving data from the network medium,
the network interface including an automatic flow control mechanism for automatically controlling a flow of data from the network medium based on availability of the receive buffers,
wherein in a first flow control mode initiated when a flow control mode signal is at a first logic level, the automatic flow control mechanism is configured to respond to a shortage of the receive buffers by automatically requesting a remote transmitter coupled to the network medium to suspend data transmission until a predetermined number of the receive buffers is available, and
in a second flow control mode initiated when the flow control mode signal is at a second logic level, the automatic flow control mechanism is configured to respond to a shortage of the receive buffers by automatically requesting the remote transmitter coupled to the network medium to suspend data transmission for a predetermined time.

4 more elements

Dependencies are inferred from the claim text.

Automatic generation of flow control frames

Life of this patent

Automatic generation of flow control frames

Life of this patent

Abstract

Claims19