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<html> <head> <meta content="en-us" http-equiv="Content-Language"> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> <link type="text/css" rel="stylesheet" href="../../../../../css/ccna.css"> <script src="../../../../../js/framesetHelper.js" language="JavaScript"></script><script language="JavaScript"> window.scrollTo(0,0); function newPage(pageID) { alert("COMMING SOON!!\nThis feature is currently in development."); } function launchMoreInfo(oid) { dash = oid.indexOf('-'); sub1 = oid.substring(0,dash); sub2 = oid.substring(dash+1); // this is an URL base on the // system that generated the static // download of the curriculum. httpref = "http://nomar.sdf.cisco.com/servlet/org.cli.delivery.rendering.servlet.MIServlet/Static=true,LMSID=DTUI,Engine=dynamic,Theme=cnamstheme,Style=ccna,Language=en,Version=2,RootID=knet-v214aCV47051/CHAPID=null/RLOID=null/RIOID=null/"; newref = httpref + sub1 +"/"+ sub2 +"/moreinfoframeset.html"; //alert("new newref :\n" + newref); window.open(newref,'MoreInfo','toolbar=no,status=yes,menubar=no,location=no,scrollbars=yes,height=442,width=756,left=20,top=20,resizable=yes') } function launchContentResource(contentID) { top.currentSupport = 0; 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It also locates TCP on the protocol graph of the TCP/IP stack.</p> <p>The purpose of this target indicator is not that the student memorize all of the fields of a TCP segment. Rather, if they can describe the most important features of segments that is sufficient. Also, it is important to relate segments to the other PDUs -- segments are encapsulated into packets which are encapsulated into frames which are converted to a bit stream on the media. The students have already seen Ethernet, Token Ring, and FDDI frame formats; and IP datagrams -- relate the TCP segment format explicitly to those diagrams.</p> <p>This TI relates to CCNA Certification Exam Objectives #1, #2, #6, and #35.</p> </span></td> </tr> </table> </td> </tr> </table> </td> </tr> </table><p> <i>Transmission Control Protocol (TCP)</i> is a connection-oriented Layer 4 (transport layer) protocol that provides reliable full-duplex data transmission. TCP is part of the TCP/IP protocol stack.<img border="0" src="../../../../../CHAPID=knet-v214aCH47512/RLOID=knet-v214aRLO47840/RIOID=knet-v214aRIO124687/knet/v214adataimage1/1.gif" width="12" height="12"></p><p>Following are the definitions of the fields in the TCP segment: <img border="0" src="../../../../../CHAPID=knet-v214aCH47512/RLOID=knet-v214aRLO47840/RIOID=knet-v214aRIO124687/knet/v214adataimage2/2.gif" width="12" height="12"></p><ul type="disc"><li> <i>Source port</i> - number of the calling port</li><li> <i>Destination port</i> - number of the called port</li><li> <i>Sequence number</i> - number used to ensure correct sequencing of the arriving data</li><li> <i>Acknowledgment number</i> - next expected TCP octet</li><li> <i>HLEN</i> - number of 32-bit words in the header</li><li> <i>Reserved</i> - set to zero</li><li> <i>Code bits</i> - control functions (such as setup and termination of a session)</li><li> <i>Window</i> - number of octets that the sender is willing to accept</li><li> <i>Checksum</i> - calculated checksum of the header and data fields</li><li> <i>Urgent pointer</i> - indicates the end of the urgent data</li><li> <i>Option-one option</i> - maximum TCP segment size</li><li> <i>Data</i> - upper layer protocol data </li></ul></td> </tr> </table> </td> </tr></table> <p> </p> <table width="100%" cellspacing="0" cellpadding="2" border="0" valign="bottom"> <tr> <td></td> </tr> </table> </body></html>⌨️ 快捷键说明
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