Method and apparatus for handling link suspend pulse and silent line state transitions of a network device

Abstract

A method and apparatus for handling data during link suspend pulse and the silent line state of a network device operating in a low power link suspend mode is presented. Accordingly, a new generation of network devices capable of operating in both the full power operational mode of prior art network devices, and a low power 'link-suspend' operational mode are presented. The low power 'link-suspend' (LS) mode reduces the power consumption of a LAN communications link at the physical layer by eliminating the need to continuously transmit standard idles to maintain link between two linked partners. In the LS mode, a low duty cycle “link-suspend-packet” (LSP) is transmitted between periods of silent line state (SLS). During the SLS, which is a non-data transmission period, the transmitter may be turned off to conserve power therefore preventing the receiver from immediately knowing the phase of an incoming data. Thus, in order to prevent loss of data, the LSPs serve to maintain link and provide information necessary to train the receiver loops so that they can quickly lock onto the incoming data. LSPs are specially constructed so that they can serve as part of the data preamble when the network devices are operating in the link suspend mode. Therefore, the nature of the LSPs is that they are compatible with the standard protocol requirements for data transmission.