TCPIP Application and Transport

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TCP/IP Application and Transport

• CPE302 TCP/IP Network Lab 2004
• Dome Potikanond
• Sakgasit Ramingwong

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TCP/IP Application and Transport

• TCP/IP Transport Layer
• TCP/IP Application Layer

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Transport Layer
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Introduction to TCP/IP Transport Layer

• The primary duties
• Transport and regulate the flow of information
  from the source to the destination, reliably and
  accurately
• Segmentation of upper-layer application data
• Establishment of end-to-end operations
• Transport of segments from one end host to
  another end host
• Flow control provided by sliding windows
• Reliability provided by sequence numbers and
  acknowledgments

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Flow Control

• Flow control avoids the problem of a transmitting
  host overflowing the buffers in the receiving
  host
• TCP provides the mechanism for flow control by
  allowing the sending and receiving host to
  communicate
• The two hosts then establish a data-transfer rate
  that is agreeable to both

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Flow Control
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Session Establishment

• Transport functionality is accomplished on a
  segment-by-segment basis (first-come,
  first-served)
• The segments can be routed to the same or
  different destinations
• The session is connection-oriented

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Establishing a Connection with a Peer System
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Establishing a Connection with a Peer System
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Establishing a Connection with a Peer System
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Three-Way Handshake

• Initializing a connection
• the two hosts must synchronize their Initial
  Sequence Numbers (ISNs) by exchanging of
  connection establishing segments that carry a
  control bit called SYN, for synchronize, and the
  ISNs
• Segments that carry the SYN bit are also called
  SYNs
• The synchronization requires each side to send
  its own initial sequence number and to receive a
  confirmation of exchange in an acknowledgment
  (ACK) from the other side
• Each side must also receive the INS from the
  other side and send a confirming ACK

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Three-Way Handshake
A?B SYN(A) initial sequence number is X ACK
number is 0 SYN bit is set ACK bit is not set
B?A ACK(A) sequence number is X 1, (B)
initial sequence number is Y SYN bit is set ACK
bit is set
A?B ACK(B) sequence number is Y 1, (A)
sequence number is X 1 SYN bit is not set ACK
bit is set
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Windowing

• Small data packets for preventing protocol
  failure
• Expectational acknowledgements
• Available during lifetime of the connection

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TCP Basic Window
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TCP Sliding Window
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Acknowledgement

• Positive acknowledgment with retransmission is
  one technique that guarantees reliable delivery
  of data
• A recipient will send back an acknowledgment
  message to the source when the data is received
• The sender keeps a record of each data packet
  (TCP segment), that it sends and expects an
  acknowledgment
• The sender also starts a timer when it sends a
  segment and will retransmit a segment if the
  timer expires before an acknowledgment arrive

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TCP Sliding Window
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TCP Sequence and Acknowledgement
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Transmission Control Protocol (TCP)

• Connection-oriented
• Layer 4
• Full-duplex data transmission
• The protocols that use TCP include
• FTP (File Transfer Protocol)
• HTTP (Hypertext Transfer Protocol)
• SMTP (Simple Mail Transfer Protocol)
• Telnet

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TCP Segment Format
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TCP Segment

• The following are the definitions of the fields
  in the TCP segment
• Source port Number of the calling port
• Destination port Number of the called port
• Sequence number Number used to ensure correct
  sequencing of the arriving data
• Acknowledgment number Next expected TCP octet
• HLEN Number of 32-bit words in the header
• Reserved Set to zero
• Code bits Control functions, such as setup and
  termination of a session
• Window Number of octets that the sender is
  willing to accept
• Checksum Calculated checksum of the header and
  data fields
• Urgent pointer Indicates the end of the urgent
  data
• Option One option currently defined, maximum
  TCP segment size
• Data Upper-layer protocol data

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User Datagram Protocol (UDP)

• Connectionless
• Layer 4
• No windowing or acknowledgments
• 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)

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UDP Segment Format
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UDP Segment

• The following are the definitions of the fields
  in the UDP segment
• Source 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

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TCP and UDP Port Number

• Issued by the Internet Assigned Numbers Authority
  (IANA)
• Numbers below 1024 are considered well-known
  ports numbers
• Numbers above 1024 are dynamically assigned ports
  numbers
• Registered port numbers are those registered for
  vendor-specific applications. Most of these are
  above 1024
• MSN?, ICQ?, SSH?, HTTPS?

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Port Numbers
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Port Numbers
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Application Layer
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Introduction to TCP/IP Application Layer

• Comprise session, presentation and application
  layers from the OSI model
• The TCP/IP application layer protocols include
  the following applications
• Domain Name System (DNS)
• File Transfer Protocol (FTP)
• Hypertext Transfer Protocol (HTTP)
• Simple Mail Transfer Protocol (SMTP)
• Simple Network Management Protocol (SNMP)
• Telnet

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Application Layer
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Domain Naming System (DNS)

• Used on the Internet for translating names of
  domains and their publicly advertised network
  nodes into IP addresses
• There are more than 200 top-level domains on the
  Internet, examples of which include the
  following
• .us United States
• .uk United Kingdom
• .th - Thailand
• There are also generic names, which examples
  include the following
• .edu educational sites
• .com commercial sites
• .gov government sites
• .org non-profit sites
• .net network service
• .mil, .int, .info, .biz, .tv

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File Transfer Protocol (FTP and TFTP)

• FTP
• Connection-oriented
• TCP
• Transfer files from one computer to another by
  copying and moving files from servers to clients,
  and from clients to servers
• TFTP
• Connectionless
• UDP
• Used on the router to transfer configuration
  files and Cisco IOS images and to transfer files
  between systems that support TFTP

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FTP Application
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Hypertext Transfer Protocol (HTTP)

• World Wide Web
• Hypertext Markup Language (HTML)
• Uniform Resource Locator (URL)
• http//www.doc.eng.cmu.ac.th/course/cpe302/

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URL
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Simple Mail Transfer Protocol (SMTP)

• Send and receive mail between mail servers
• Transports email messages in ASCII format using
  TCP
• The most popular mail client protocols are POP3
  and IMAP4
• MS Outlook
• Mozilla Thunderbird
• Eudora pro

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Sending E-mail
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Simple Network Management Protocol (SNMP)

• Facilitates the exchange of management
  information between network devices
• Manage network performance
• Find and solve network problems
• Plan for network growth
• UDP

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SNMP

• An SNMP managed network consists of the following
  three key components
• Network management system (NMS)
• NMS executes applications that monitor and
  control managed devices
• Managed devices
• Network nodes that contain an SNMP agent and that
  reside on a managed network
• Routers, access servers, switches, and bridges,
  hubs, computee, or printers.
• Agents
• Network-management software modules that reside
  in managed devices
• An agent has local knowledge of management
  information and translates that information into
  a form compatible with SNMP.

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SNMP-Managed Network
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Telnet

• Provides the ability to login to a remote
  Internet host that is running a Telnet server
  application and then to execute commands from the
  command line
• Telnet client is referred to as a local host
• Telnet server, which uses special software called
  a daemon, is referred to as a remote host

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Telnet