Automatic Speed Negotiation

• Each device transmits at respective assumed rate of operation

  • Storage device fails to achieve word sync at 2Gb/s
  • Server host adapter fails to achieve 2Gb/s word sync in allotted time

• Server host adapter toggles to 1Gb/s data rate

  • Storage device achieves word sync at 1Gb/s
  • Server host adapter achieves word sync at 1Gb/s

• Host adapter initiates primitives to bring up link

2Gb/s Capable Server

1Gb/s Storage

• 2Gb/s Sync Pattern

1Gb/s Sync Pattern

• 1Gb/s Sync Pattern

1Gb/s Sync Pattern

Speed Negotiation Example

No word sync achieved

Word sync achieved

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