ITE PC v4.0 Chapter 1

Chapter 5:Transport LayerNetwork Basics 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID#Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential1Cisco Networking Academy programNetwork BasicsChapter 5: Transport Layer 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrChapter 55.0 Introduction5.1 Transport Layer Protocols5.2 TCP and UDP5.3 SummaryPresentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential2Chapter 5 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrChapter 5: ObjectivesDescribe the purpose of the transport layer in managing the transportation of data in end-to-end communication.Describe characteristics of the TCP and UDP protocols, including port numbers and their uses.Explain how TCP session establishment and termination processes facilitate reliable communication.Explain how TCP protocol data units are transmitted and acknowledged to guarantee delivery.Explain the UDP client processes to establish communication with a server.Determine whether high-reliability TCP transmissions, or non-guaranteed UDP transmissions, are best suited for common applications.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential3Chapter 5: Objectives 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr5.1 Transport Layer Protocols

2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID#Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential45.1 Transport Layer Protocols 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Transportation of DataRole of the Transport Layer (Cont.)Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential5.1.1.2 Role of the Transport Layer (Cont.)6 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrTransportation of DataConversation Multiplexing (Cont.)

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential85.1.1.3 Conversation Multiplexing (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrTransportation of DataTransport Layer ReliabilityTCP/IP provides two transport layer protocols, TCP and UDP. TCP Provides reliable delivery ensuring that all of the data arrives at the destination.Uses acknowledged delivery and other processes to ensure delivery.Makes larger demands on the network more overhead.UDPProvides just the basic functions for delivery no reliability.Less overhead.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential95.1.1.4 Transport Layer Reliability5.1.1.5 TCP5.1.1.6 UDP

2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrTransportation of DataThe Right Transport Layer ProtocolTCP or UDPThere is a trade-off between the value of reliability and the burden it places on the network.Application developers choose the transport protocol based on the requirements of their applications.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential105.1.1.7 The Right Transport Layer Protocol for the Right Application

2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrTransportation of DataThe Right Transport Layer Protocol (Cont.)

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential115.1.1.7 The Right Transport Layer Protocol for the Right Application

2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPIntroducing TCP

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential125.1.2.1 Introducing TCP 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPIntroducing TCP (Cont.)Defined in RFC 793Connection-oriented Creates a session between the source and destinationReliable delivery Retransmits lost or corrupt dataOrdered data reconstruction Reconstructs numbering and sequencing of segmentsFlow control Regulates the amount of data transmittedStateful protocol Tracks the sessionPresentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential135.1.2.1 Introducing TCP (cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPIntroducing UDPDefined in RFC 768ConnectionlessUnreliable deliveryNo ordered data reconstructionNo flow controlStateless protocol

Applications that use UDP:Domain Name System (DNS)Video StreamingVoIP

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential145.1.2.3 Introducing UDP 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPSeparating Multiple CommunicationsTCP and UDP use port numbers to differentiate between applications.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential155.1.2.5 Separating Multiple Communications 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPTCP and UDP Port Addressing (Cont.)The combination of the source and destination IP addresses and the source and destination port numbers is known as a Socket.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential165.1.2.7 TCP and UDP Port Addressing (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrIntroducing TCP and UDPTCP and UDP Port Addressing (Cont.)

TCP Port NumbersPresentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential175.1.2.8 TCP and UDP Port Addressing (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Introducing TCP and UDPTCP and UDP Port Addressing (Cont.)

UDP Port NumbersPresentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential185.1.2.8 TCP and UDP Port Addressing (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Introducing TCP and UDPTCP and UDP Port Addressing (Cont.)netstat is used to examine TCP connections that are open and running on a networked host.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential195.1.2.9 TCP and UDP Port Addressing (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Introducing TCP and UDPTCP and UDP SegmentationThe Transport Layer divides the data into pieces called segments and adds a header for delivery over the network.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential205.1.2.10 TCP and UDP Segmentation 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

5.2 TCP and UDP

2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID#Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential215.2 TCP and UDP 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Reliable DeliveryThe reliability of TCP communication is obtained through the use of connection-oriented sessions.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential225.2.1.1 TCP Reliable Delivery

2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Server Processes

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential235.2.1.2 TCP Server Processes 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Server Processes (Cont.)

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential245.2.1.2 TCP Server Processes (Cont.) 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Connection, Establishment, and TerminationThree-Way HandshakeEstablishes that the destination device is present on the networkVerifies that the destination device has an active service and accepts requests on the destination port number that the initiating client intends to use for the sessionInforms the destination device that the source client intends to establish a communication session on that port number

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential255.2.1.3 TCP Connection, Establishment, and Termination 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Three-Way Handshake Step 1Step 1: The initiating client requests a client-to-server communication session with the server.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential265.2.1.4 TCP Three Way Handshake Step 1 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP CommunicationTCP Three-Way Handshake Step 2Step 2: The server acknowledges the client-to-server communication session and requests a server-to-client communication session.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential275.2.1.5 TCP Three Way Handshake Step 2 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrTCP Communication TCP Three-Way Handshake Step 3Step 3: The initiating client acknowledges the server-to-client communication session.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential285.2.1.6 TCP Three Way Handshake Step 3 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Protocol Data UnitsTCP Reliability Ordered DeliverySequence numbers are used to reassemble segments into the original order.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential295.2.2.1 TCP Reliability Ordered Delivery 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrThe sequence number and acknowledgement number are used together to confirm receipt.

The window size is the amount of data that a source can transmit before an acknowledgement must be received.

Protocol Data Units TCP Reliability Acknowledgement and Window SizePresentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential305.2.2.2 TCP Reliability Acknowledgement and Window size 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Protocol Data Units TCP Reliability Data Loss and Retransmission Data Loss and Retransmission When TCP at the source host has not received an acknowledgement after a predetermined amount of time, it goes back to the last acknowledgement number that it received and retransmits data from that point forward.Flow Control Uses the Window Size field in the TCP header to specify the amount of data that can be transmitted before an acknowledgement must be received.Adjusts the effective rate of data transmission to the maximum flow that the network and destination device can support without loss.Manages the rate of transmission so that all data is received and retransmissions are minimized.Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential315.2.2.3 TCP Reliability - Data Loss and Retransmission5.2.2.4 TCP Flow Control - Window Size and Retransmission 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrProtocol Data Units TCP Flow Control Congestion Avoidance

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential325.2.2.5 TCP Flow Control Congestion Avoidance 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

UDP CommunicationUDP Low Overhead vs. ReliabilityUDP:Simple protocol that provides the basic transport layer functionUsed by applications that can tolerate small loss of dataUsed by applications that cannot tolerate delayUDP used by:DNSSimple Network Management Protocol (SNMP)Dynamic Host Configuration Protocol (DHCP)Trivial File Transfer Protocol (TFTP)IP telephony or VoIPOnline games

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential335.2.3.1 UDP Low Overhead vs. Reliability 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

UDP CommunicationDatagram Reassembly

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential345.2.3.2 Datagram Reassembly 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

UDP CommunicationUDP Server Processes and RequestsUDP-based server applications are assigned well-known or registered port numbers.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential355.2.3.3 UDP Server Processes and Requests 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

UDP CommunicationUDP Server and Client ProcessesUDP client process randomly selects a port number from range of dynamic port numbers as the source port.

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential365.2.3.4 UDP Client Processes 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP or UDP, that is the QuestionApplications Using TCP

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential375.2.4.1 Applications Using TCP 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

TCP or UDP, that is the QuestionApplications Using UDP

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential385.2.4.2 Applications Using UDP 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

5.3 Summary

2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID#Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential395.3 Summary 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scrChapter 5: SummaryIn this chapter, you learned:The role of the transport layer is to provide three main services: multiplexing, segmentation and reassembly, and error checking. It does this by: Dividing data received from an application into segments.Adding a header to identify and manage each segment.Using the header information to reassemble the segments back into application data.Passing the assembled data to the correct application.How TCP and UDP operate and which popular applications use each protocol.Transport Layer functions are necessary to address issues in QoS and security in networks.Ports provide a tunnel for data to get from the transport layer to the appropriate application at the destination.Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential40Chapter 5: Summary 2006, Cisco Systems, Inc. All rights reserved.Presentation_ID.scr

Presentation_ID# 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential