ccna exp1 - chapter04 - osi transport layer

Chapter 4 - OSI Transport LayerCCNA Exploration version 4.0

Hc vin mng Bach Khoa - Website: www.bkacad.com

CCNA Exploration V4.0 www.BKACAD.com

Hc vin mng Bach Khoa - Website: www.bkacad.com*ObjectivesExplain the role of Transport Layer protocols and services in supporting communications across data networksAnalyze the application and operation of TCP mechanisms that support reliability Analyze the application and operation of TCP mechanisms that support reassembly and manage data loss.Analyze the operation of UDP to support communicate between two processes on end devices



Hc vin mng Bach Khoa - Website: www.bkacad.com*Transport Layer Role and ServicesExplain the purpose of the Transport layer Enables multiple applications to communicate over the network at the same time on a single device Ensures that, if required, all the data is received reliably and in order by the correct application.Employs error handling mechanisms.



Hc vin mng Bach Khoa - Website: www.bkacad.com*Transport Layer Role and ServicesMajor functions of the transport layer and the role it plays in data networks Tracking the individual communication between applications on the source and destination hosts.Segmenting data and managing each piece.Reassembling the segments into streams of application data.Identifying the different applications.



Hc vin mng Bach Khoa - Website: www.bkacad.com*Separating Multiple Communications



Hc vin mng Bach Khoa - Website: www.bkacad.com*Segmentation



Hc vin mng Bach Khoa - Website: www.bkacad.com*Controlling the Conversation



Hc vin mng Bach Khoa - Website: www.bkacad.com*Controlling the Conversation



Hc vin mng Bach Khoa - Website: www.bkacad.com*Transport Layer Role and Services









Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format:



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format: Port numberSource Port 16 bits.Destination Port 16 bits.



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format: SequenceSequence Number: 32 bitsThe sequence number of the first data octet in this segment (except when SYN is present).



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format: AcknowledgmentAcknowledgment Number: 32 bitsThis field contains the value of the next sequence number the sender of the segment is expecting to receive.



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format: Code bitsControl Bits: 8 bits ACK: Acknowledgment field significantRST: Reset the connectionSYN: Synchronize sequence numbersFIN: No more data from sender



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP Header format: WindowWindow: 16 bitsThe number of data octets beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept.



Hc vin mng Bach Khoa - Website: www.bkacad.com*User Datagram Protocol (UDP)

UDP is a simple protocol that exchanges datagrams, without acknowledgments or guaranteed delivery. Error processing and retransmission must be handled by higher layer protocols UDP is designed for applications that do not need to put sequences of segments together



Hc vin mng Bach Khoa - Website: www.bkacad.com*UDP header fieldsSource port Number of the calling port Destination port Number of the called port Length Number of bytes including header and data Checksum Calculated checksum of the header and data fields Data Upper-layer protocol data The protocols that use UDP include: - TFTP (Trivial File Transfer Protocol). - SNMP (Simple Network Management Protocol). - DHCP (Dynamic Host Control Protocol). - DNS (Domain Name System).






Hc vin mng Bach Khoa - Website: www.bkacad.com*Port and TCP port



Hc vin mng Bach Khoa - Website: www.bkacad.com*UDP port



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP and UDP Common Port



Hc vin mng Bach Khoa - Website: www.bkacad.com*TCP and UDP port numbers

Both TCP and UDP use port (socket) numbers to pass information to the upper layers. Port numbers are used to keep track of different conversations crossing the network at the same time.



Hc vin mng Bach Khoa - Website: www.bkacad.com*Netstat command



Hc vin mng Bach Khoa - Website: www.bkacad.com*Application and Operation of TCP MechanismsDescribe the role of port numbers in establishing TCP sessions and directing segments to server process



Hc vin mng Bach Khoa - Website: www.bkacad.com*3 way hand shake



Hc vin mng Bach Khoa - Website: www.bkacad.com*Application and Operation of TCP MechanismsTrace the steps in the handshake in the establishment of TCP sessions



Hc vin mng Bach Khoa - Website: www.bkacad.com*Application and Operation of TCP MechanismsTrace the steps in the handshake in the termination of TCP sessions



Hc vin mng Bach Khoa - Website: www.bkacad.com*Managing TCP SessionsTCP uses sequence numbers to reconstruct the data stream with segments placed in the correct order. Sequence number incremented by the number of bytes that have been transmitted.



Hc vin mng Bach Khoa - Website: www.bkacad.com*Managing TCP SessionsTrace the steps used by the TCP protocol in which sequence numbers and acknowledgement numbers are used to manage exchanges in a conversation



Hc vin mng Bach Khoa - Website: www.bkacad.com*Managing TCP SessionsDescribe the retransmission remedy for lost data employed by TCP (refer to 4.3.3.1)



Hc vin mng Bach Khoa - Website: www.bkacad.com*Managing TCP Sessions












Hc vin mng Bach Khoa - Website: www.bkacad.com*Managing TCP SessionsTCP uses window size and acknowledgement to manage data loss and congestion during a session.






Hc vin mng Bach Khoa - Website: www.bkacad.com*Flow Control When datagrams arrive too quickly for a host or gateway to process and the transport function can issue a not ready indicator to the sender to stop sending data. When the receiver can handle additional data, the receiver sends a ready transport indicator. When this indicator is received, the sender can resume the segment transmission.



Hc vin mng Bach Khoa - Website: www.bkacad.com*UDP ProtocolUDP is a simple protocol that provides the basic Transport layer functions. It much lower overhead than TCP, does not provide the sophisticated retransmission, sequencing, and flow control mechanisms. Some UDP applications:Domain Name System (DNS)Simple Network Management Protocol (SNMP)Dynamic Host Configuration Protocol (DHCP) Routing Information Protocol (RIP) Trivial File Transfer Protocol (TFTP)Online games



Hc vin mng Bach Khoa - Website: www.bkacad.com*UDP ProtocolDescribe in detail the process specified by the UDP protocol to reassemble PDUs at the destination device



Hc vin mng Bach Khoa - Website: www.bkacad.com*UDP ProtocolTrace the steps as the UDP protocol and port numbers are utilized in client-server communication.



Hc vin mng Bach Khoa - Website: www.bkacad.com*


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ccna exp1 - chapter04 - osi transport layer

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