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Method and apparatus for nodes in network to avoid shrinkage of an interframe gap

DC
  • US 4,878,219 A
  • Filed: 04/28/1988
  • Issued: 10/31/1989
  • Est. Priority Date: 04/28/1988
  • Status: Expired due to Term
First Claim
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1. An output controller in a repeater node for controlling data transfers in a data communication system, the data communication system including a plurality of nodes coupled in a network for transferring frames of data from a source node to a destination node through a plurality of repeater nodes, wherein the repeater node receives a plurality of bytes in a frame from an upstream node, stores the plurality of bytes in an elasticity buffer, and transmits the plurality of bytes in the frame to a downstream node, wherein a last byte of a preceding frame and a starting delimiter for a subsequent frame are separated by a preamble including at least a minimum number of idle bytes, wherein each node in the network is operated by an independent local clock, and wherein the repeater node includes an input controller, the output controller comprising:

  • means coupled to the elasticity buffer for transmitting bytes to the downstream node in response to a local clock signal;

    means coupled to the transmitting means for indicating an idle byte is being transmitted to the downstream node;

    means coupled to the idle byte indicating means for counting the number of idle bytes being transmitted to the downstream node;

    control means coupled to the counting means and responsive to an indication from the input controller of receipt of the starting delimiter for the subsequent frame, for asserting a control signal to enable transmission of the starting delimiter to the downstream node in response to an idle byte count indicating that more than a threshold number of idle bytes is being transmitted to the downstream node, and for not asserting the control signal to delay transmission of the starting delimiter in response to an idle byte count indicating that the threshold number of idle bytes is being transmitted to the downstream node; and

    means coupled to the control means and the transmitting means for transmitting an additional idle byte to the downstream node in response to deassertion of the control signal at times when an equal signal is received indicating the starting delimiter is ready to be output.

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