12 Replies Latest reply: Mar 22, 2009 1:03 PM by Scott Morris - CCDE/4xCCIE/2xJNCIE RSS

    "Error Detection" and "Error Recovery" with TCP


      I need another "cisco answer" here folks.


      I was watching another training video and the instructor mentioned the following example:


      Data Sender sends 4 segments to a Data Recipient:


      - Seq 100

      - Seq 200

      - Seq 300

      - Seq 400


      If Sequence 200 didn't make it to the recipient, the recipient would send back an ACK 200 (which is considered error detection) and the sender would resend the lost segment (which is considered error recovery).


      I can't help but disagree with this... I would think that the process of requesting segments to be resent (and sending them) is a function of "error recovery" and that error detection is associated with other error checking functions (for example the TCP payload checksum).


      My question is: What components of TCP pertain to "Error recovery" and what components of TCP pertain to "Error detection"? Cisco answers please