1 Reply Latest reply: Mar 27, 2012 4:41 AM by David - CCNA R&S RSS

    Error in TCP ACK w/ errors diagram? INCD1 OCG Ed: 3


      Possible TCP Syn_ACK error.pngfrom CCENT/CCNA ICND 1 640-822 Official Certification Guide; page 147,  Wendell Odom.


      Hello CLN Team,


      Anyone know of where I can find the errata for the OCG ed:3? I believe sequence 3000 is the one that is lost according to the "explosion" symbol but the following ACK and captions impliy that the web browser did not receive and is expecting sequence 2000.


      Lastly, once sequence 2000 is received, if the web browser already has 3000, shouldn't the last ACK be 4000?


      Or am I off target here. Thanks




      Message was edited by: RG_WB reason: wrong reference page

        • 1. Re: Error in TCP ACK w/ errors diagram? INCD1 OCG Ed: 3
          David - CCNA R&S

          Hi RG,


          I have the 3rd edition and it still has an explosion on the 3rd. However it does say above it "the second TCP segment was lost or is in error" So I believe the explosion is in the wrong sequence number, it should be moved from sequence number 3000 to 2000.


          Which would explain the forward acknowledgement being 2000, as it is expecting 2000 next as it never got it. So the 1000 bytes is forwarded with sequence number 2000 as per diagram but the last ACK should have a sequence number of 4000 as that is what it is expecting next. As per what is says in the blurb box on the right.