Networking, Data Communication & Telecommunication

1. TCP/IPTCP/IP

2. Origins of TCP/IPOrigins of TCP/IP
• Transmission Control Protocol/Internet Protocol
(TCP/IP)
– Protocol suite whose invention and evolution resulted from
a coordinated effort by the United States Department of
Defense (DOD)
• Advanced Research Projects Agency (ARPA)
– DOD branch responsible for creation and proliferation of
the Internet and TCP/IP protocol suite
– Advanced Research Projects Agency Network
(ARPANET)
• Original name of the Internet

3. TCP/IP is the Internet Communication ProtocolTCP/IP is the Internet Communication Protocol
• A communication protocol is a description of the rules
computers must follow to communicate with each other.
• The Internet communication protocol defines the rules for
computer communication over the Internet.
• TCP/IP defines how electronic devices (like computers)
should be connected to the Internet, and how data should be
transmitted between them.

4. TCP/IPTCP/IP
• TCP/IP is TCP and IP working together.
• TCP takes care of the communication between your
application software (i.e. your browser) and your
network software.
• IP takes care of the communication with other
computers.

5. TCP/IPTCP/IP
• TCP is responsible for breaking data down into IP
packets before they are sent, and for assembling the
packets when they arrive.
• IP is responsible for sending the packets to the
correct destination.

6. Your Browser and Your Server Use TCP/IPYour Browser and Your Server Use TCP/IP
• Internet browsers and Internet servers use TCP/IP to
connect to the Internet.
• Your browser uses TCP/IP to access Internet servers,
and servers use TCP/IP to send HTML back to your
browser.

7. Your E-Mail Uses TCP/IPYour E-Mail Uses TCP/IP
• Your e-mail program uses TCP/IP to connect to the
Internet for sending and receiving e-mails.

8. Your Internet Address is TCP/IPYour Internet Address is TCP/IP
• Your Internet address "222.48.162.2" is a part of
the standard TCP/IP protocol (and so is your
domain name "www.myroomplace.com").

9. Overview of the TCP/IP ProtocolOverview of the TCP/IP Protocol
SuiteSuite
• Four layers of the TCP/IP protocol suite :
– Application
– Transport
– Internetwork
– Network Interface
• Series of documents called Requests for
Comments (RFCs) define, describe, and
standardize implementation and configuration of the
TCP/IP protocol suite
– The Internet Network Information Center
(InterNIC) is responsible for maintaining these standards

10. Overview of the TCP/IP ProtocolOverview of the TCP/IP Protocol
SuiteSuite
Figure 3-1:
Protocol
architecture
comparison

11. • Protocols at the TCP/IP Application layer include:
– File Transfer Protocol (FTP)
– Trivial File Transfer Protocol (TFTP)
– Network File System (NFS)
– Simple Mail Transfer Protocol (SMTP)
– Terminal emulation protocol (telnet)
– Remote login application (rlogin)
– Simple Network Management Protocol (SNMP)
– Domain Name System (DNS)
– Hypertext Transfer Protocol (HTTP)

12. Application LayerApplication Layer
• Protocols that exist at this layer include:
– File Transfer Protocol (FTP)
• Moves files between devices.
• Performs basic interactive file transfers between hosts.
– Trivial File Transfer Protocol (TFTP)
• File transfer utility used on the Internet. TFTP uses UDP (User
Datagram Protocol*2) to transfer files and is therefore less
reliable than FTP which uses TCP in transferring files.
• User Datagram Protocol that operates at the Transport layer and
transports data unreliably over IP. Sometimes known as
connectionless communication as the messages are sent without
expectation of acknowledgment.
– No connection negotiation process
– Faster than TCP

13. Application LayerApplication Layer
– Network File System (NFS)
• enable transparent access to remote network resources
– Simple Mail Transfer Protocol (SMTP)
• Supports basic message delivery services
• Provides electronic mail services
– Terminal emulation protocol (telnet)
• Serves as a terminal emulation protocol
• Enables users to execute terminal sessions with
remote hosts
– Remote login application (rlogin)
• Utility that allows remote computers to connect to
other computers or devices

14. Application LayerApplication Layer
– Simple Network Management Protocol (SNMP)
• Protocol that provides network administrators the ability to centrally control and
monitor the network.
• A protocol that is used to collect management information from network
devices.
– Domain Name System (DNS)
• Also called name service; this application maps IP addresses to the names
assigned to network devices.
– Hypertext Transfer Protocol (HTTP)
• Protocol used for communication on the World Wide Web.
• The protocol used by Web browsers and Web servers to
transfer files, such as text and graphic files.

15. Transport LayerTransport Layer
• Two protocols reside at this layer:
– TCP
– User Datagram Protocol (UDP)
• Ports
• connection point, usually for network cable, on a device e.g. hub, router, bridge
and switch
– Both TCP and UDP use port numbers for communication
between hosts
– Well Known Port Numbers
• TCP and UDP ports from 0 through 1023 on which client
applications expect to find common Internet services

16. Transport LayerTransport Layer
• Performs end-to-end packet delivery, reliability, and
flow control
• Protocols:
– TCP provides reliable, connection-oriented
communications between two hosts
• Requires more network overhead
– UDP provides connectionless datagram services between
two hosts
• Faster but less reliable
• Reliability is left to the Application layer

17. Well Known TCP and UDP PortWell Known TCP and UDP Port
Numbers from RFC 1700Numbers from RFC 1700
• TCP port 20 – FTP data transfer
• TCP port 21 – FTP control port
• TCP port 23 – Telnet
• TCP port 25 – SMTP
• TCP & UDP port 53 – DNS
• TCP port 80 – HTTP Web services

18. TCP Three-Way HandshakeTCP Three-Way Handshake
• TCP three-way handshake
– Establishes a reliable connection between two points
– TCP transmits three packets before the actual data transfer
occurs
– Before two computers can communicate over TCP, they
must synchronize their initial sequence numbers (ISN)
– A reset packet (RST) indicates that a TCP connection is
to be terminated without further interaction

19. TCP Three-Way HandshakeTCP Three-Way Handshake
• Before two computers can communicate over TCP, they
must synchronize their initial sequence numbers (ISN)
• When a synchronization request is sent, it is abbreviated
SYN
• When an acknowledgement is sent, the abbreviation is
ACK
– Exceptional acknowledgment
• Acknowledgment number refers to the sequence
number refers to the sequence number expected
next

20. TCP Three-Way HandshakeTCP Three-Way Handshake

21. TCP Three-Way HandshakeTCP Three-Way Handshake

22. Internetwork LayerInternetwork Layer
• Four main protocols function at this layer:
– Internet Protocol (IP)
– Internet Control Message Protocol (ICMP)
• Uses eight different message types to manage 11 different aspects of IP
communications
– Address Resolution Protocol (ARP)
• * Protocol that works at the Internetwork layer of the TCP/IP networking model
• Resolves a known IP address to an unknown MAC address
• A routed protocol
• Maps IP addresses to Mac address
• ARP tables contains the MAC and IP addresses of other devices on the network
– Reverse Address Resolution Protocol (RARP)
• Protocol used to resolve the clients’ unknown IP address to the clients MAC
address.
• In the case of a diskless workstation, a source host will know its MAC address but
not its IP address

23. Internetwork LayerInternetwork Layer
• ARP (continued)
– When a computer transmits a frame to a
destination on the local network
• It checks the ARP cache for an IP to MAC address
mapping for the destination node
• ARP request
– If a source computer cannot locate an IP to MAC
address mapping in its ARP table
• It must obtain the correct mapping

25. Internetwork LayerInternetwork Layer
• ARP request (continued)
– A source computer broadcasts an ARP request to
all hosts on the local segment
• Host with the matching IP address responds this
request
• ARP request frame
– See Figure 3-7
• ARP cache life
– Source checks its local ARP cache prior to
sending packets on the local network

26. Internetwork LayerInternetwork Layer

27. Internetwork LayerInternetwork Layer
• Reverse Address Resolution Protocol (RARP) ..Continued
– Similar to ARP
– Used primarily by diskless workstations
• Which have MAC addresses burned into their network
cards but no IP addresses
– Client’s IP configuration is stored on a RARP server

28. Internetwork LayerInternetwork Layer
• RARP request frame
– See Figure 3-8
• RARP client
– Once a RARP client receives a RARP reply, it configures
its IP networking components
• By copying its IP address configuration information into its local
RAM
• ARP and RARP compared
– ARP is concerned with obtaining the MAC address of
other clients
– RARP obtains the IP address of the local host

30. Internetwork LayerInternetwork Layer
• The Ping utility
– Packet Internet Groper (Ping) utility verifies
connectivity between two points
– Uses ICMP echo request/reply messages

31. Network Interface LayerNetwork Interface Layer
• Plays the same role as the Data Link and
Physical layers of the OSI model
• The MAC address, network card drivers, and
specific interfaces for the network card
function at this level of the TCP/IP protocol
stack
• No specific IP functions exist at this layer
because the layer’s focus is on communication
with the network card and other networking
hardware

32. Understanding Frame TransmissionUnderstanding Frame Transmission
• Each host on a segment evaluates the frame
– To determine whether the listed destination MAC address
matches its own or is a broadcast to all hosts
• The host makes a copy of the frame and sends the
original along the network path
• On the destination host, frames are sent up the
TCP/IP stack
– Removing each layer header information
• For a packet to be routed on a TCP/IP internetwork
– An IP address and MAC address are required for both the
source and destination hosts

33. Routers on the NetworkRouters on the Network
• A router requires:
– An IP address for every network segment to which it is
connected
– A separate network interface or port for each network
segment
• Computers send frames to destinations that are not
on their segment to the router (default gateway)
• The router must determine which subnet should
receive the frame
– The router references its routing table

35. Chapter SummaryChapter Summary
• TCP/IP is not limited to transmission control and
Internet protocols
• TCP/IP was started by the Defense Advanced
Research Projects Agency (DARPA)
• TCP/IP maps to a four-layer network model:
Application, Transport, Internetwork, and Network
Interface
• The Application layer in the TCP/IP model covers
the Application, Presentation, and Session layers of
the OSI reference model

36. Chapter SummaryChapter Summary
• The TCP and UDP protocols reside at the Transport layer
of the TCP/IP networking model
• Both TCP and UDP use port numbers from 1 to 65,535
to establish their communications between two points
• The Internet Protocol (IP) resides at the Internetwork
layer and provides the logical address that can be passed
through a router
• You can use the Ping utility with IP and ICMP to
diagnose and troubleshoot network connections

37. Chapter SummaryChapter Summary
• Address Resolution Protocol (ARP) and Reverse ARP
(RARP) reside in the Internetwork layer
• The MAC address is the final leg of communication
between hosts
• Routing tables can be created manually and dynamically