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Phase re-alignment of SONET/SDH network switch without pointer manipulation

  • US 6,751,238 B1
  • Filed: 04/20/2000
  • Issued: 06/15/2004
  • Est. Priority Date: 04/20/2000
  • Status: Expired due to Fees
First Claim
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1. A skew-tolerant distributed network switch comprising:

  • a plurality of network interface ports containing;

    ingress ports, coupled to receive input data streams from external sources;

    egress ports, coupled to transmit data streams over external links;

    switch elements, coupled together and to the ingress and egress ports, to form a switch fabric for switching cell-packets from an ingress port to an egress port;

    each network interface port receiving a clock pulse that is synchronized to the data streams, wherein different network interface ports receive the clock pulse with varying skews to the data streams;

    input buffers, in the ingress ports, for buffering data from the input data streams;

    a packetizer, coupled to the input buffers, for forming cell-packets from the input data stream, the cell-packets being injected into the switch fabric by the ingress ports and routed to the egress ports through the switch elements;

    wherein the input data streams are organized into data frames that comprise one or more of the cell-packets;

    wherein the clock pulse is for indicating a frame boundary in the input data streams;

    output buffers, in the egress ports, for receiving and storing data from the cell-packets routed through the switch fabric, the cell-packets being re-ordered into a same sequence order as within the input data streams;

    transmitters, in the egress ports and coupled to the external links, for transmitting data from the cell-packets stored in the output buffers over the external links; and

    clock triggers, receiving the clock pulse, and coupled to the transmitters, for delaying transmission of the data in the frames until a clock pulse is received by the clock trigger;

    wherein the cell-packets from a frame are formed and injected into the switch fabric after a first clock pulse is received by the ingress port, but before the next clock pulse is received by the ingress port;

    wherein the cell-packets are received by the egress port before the next clock pulse;

    wherein the next clock pulse is a next pulse after the first clock pulse, whereby the cell-packets are formed and routed through the switch fabric within one clock period and whereby clock skews are tolerated by delaying transmission of the data from the egress ports until a next clock pulse is received.

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