1. CPMT 1449 Computer Networking Technology – Lesson 3
CPMT 1449 Computer Networking Technology – Lesson 3.1-Chapter 4 Introduction to TCP/IP Protocols

2. Learning Objectives
Identify and explain the functions of the core TCP/IP protocols
Explain how the TCP/IP protocol correlate to the OSI model
Discuss addressing schemes for TCP/IP in IPv4 and IPv6
Describe the purpose and implementation of DNS (Domain Name System) and DHCP (Dynamic Host Configuration Protocol)
Identify the well-known ports for key TCP/IP services
Describe common application layer TCP/IP protocols

3. TCP/IP Characteristics
Transmission Control Protocol/Internet Protocol
Actually a whole suite of Protocols
Developed in the late 1960s by the Department of Defense
Popularity due to
Low costs
Communicate between dissimilar platforms
Open Source
Uses routable protocols
Very flexible – can run on any network
Has several “core” protocols

4. TCP Segment Source Port Destination Port Sequence Number
Acknowledgement Number
TCP Header Length
Reserved
Flags
URG
ACK
PSH
RST
SYN
FIN
Sliding Window Size
Checksum
Urgent Pointer
Options
Data

5. Transmission Control Protocol (TCP) Connection Oriented/Reliable
Three-way Handshake
SYN – synchronization request for a connection
SYN-ACK – synchronization- acknowledgement confirmation that the distant end node is willing to make the connection
ACK – acknowledgement acknowledges the SYN-ACK
Connection Established 1
SYN with SEQ# 558 2
SYN-ACK with SEQ# 669/ACK with SEQ# 559 3
ACK with SEQ# 559/ACK with SEQ# 670
Connection Established!

6. User Datagram Protocol (UDP) Connectionless Oriented/Unreliable
Has only 4 field in its header
Source port
Destination port
Length
Checksum
Layer 4 protocol
More efficient that TCP
Used for live audio or video transmissions
No acknowledgements
UDP Header

7. Internet Protocol (IP)
Network Layer protocol
Contains information on how and where data should be delivered including the source and destination IP addresses
Subprotocol that allows TCP/IP to traverse more than one LAN segment and more than one type of network through a router

8. IP Packet or IP Datagram
Version
Internet Header Length
Differentiated Services
Total Length
Identification
Flags
Fragment Offset
Time To Live
Protocol
Header Checksum
Source IP
Destination IP
Options
Padding
Data

9. Internet Control Message Protocol (ICMP)
Layer 3 protocol
Reports success or failure of data delivery
Only provides error detection not correction
Aids in troubleshooting
Ping Command

10. Internet Group Management Protocol (IGMP)
Layer 3 Protocol
Manages multicasting
Multicasting allows one node to send traffic destined for multiple nodes
Routers use this protocol to determine which multicasting group other nodes belong to

11. Address Resolution Protocol (ARP)
Layer 3 Protocol
Maps the unknown MAC address to the known IP address of a given node
The requesting node send a broadcast message that states; “I have this IP address, if this is your IP address please send me your MAC address.”
The node with that IP address replies with its MAC address in a broadcast message
The requesting node then places this information in its ARP table/cache
Two types of ARP table/cache entries
Dynamic – created when the makes an ARP request that cannot be satisfied by searching the ARP table
Static – entries that someone has entered manually into the ARP table

12. Reverse Address Resolution Protocol (RARP)
Layer 3 protocol
Used in earlier networks when workstations did not have the memory or processing power of today’s machines
Maps an unknown IP address to a known MAC address
The RARP request is sent to a RARP server that maintains a table of MAC-to-IP address maps
The server queries the RARP table to find the IP address of the associated MAC address
The server then returns the IP address to the requesting node

13. IPv4 Addresses
IP address is a 32 bit number divided into 4 bytes each and separated by periods
Each byte equals 8 bits therefore each byte is referred to as an octet
Although 8 bits have 256 possible combinations only 254 numbers can be used
The number 0 is a reserved placeholder and represents the entire network address
The number 255 is reserved for broadcast transmissions

14. IP Addresses – Classes There are 5 different classes
The first three classes are used for LANs
The other 2 classes are reserved for multicasting and experimental use

15. IP Addresses - Network and Host

16. Private IPv4 Addresses 10.0.0.0 – 10.255.255.255 – Private networks
– – Loopback addresses
– – Automatic Private IP Addressing
– Private networks
– Private networks

17. Viewing IP Information
From a Windows OS
Open a command prompt – Start button > All Programs > Accessories > Command Prompt
Type the command ipconfig /all and press enter

18. Viewing IP Information – UNIX/Linux
From a UNIX or Linux OS
Open a terminal window (shell)
Type ifconfig –a at the shell prompt

19. Dotted Decimal Notation
The most common way to express an IP address
A decimal number from (256 possibilities) represents each binary octet
Example:

20. Binary Each dotted decimal notation number has a binary equivalent
When we take our example IP address –
The first octet 136 is converted as follows
The other octets are converted in the same way
The IP address expressed in binary is:

21. Subnet Mask
32 bit number that identifies the network segment or subnet and informs the rest of the network about the segment/subnet (subnet is the common name for network segment)
Used in conjunction with the IP address and is assigned manually or automatically through DHCP (covered in a later slide)
Can be expressed with either binary or dotted decimal notation
Example
All of the bits in the first three octets are turned on or have a value of 1 and represents the network portion of the subnet
The last octet has no bits turned on or a value of 0 and represents the host portion of the subnet

22. Assigning IP Addresses
Every node on the LAN or network must have a unique IP address assigned
Can be done manually or automatically
Manual configuration (Static IP address)
Automatic configuration (DHCP)

23. Bootstrap Protocol (BOOTP)
Older protocol developed in the mid 1980s
Application Layer protocol
Used a central list of IPs and the associated MAC address of each device and assigned IPs automatically – dynamically assigns the IP address also called dynamic IP
When a BOOTP client connects
The client sends a broadcast message that contains its MAC address to the BOOTP server requesting an IP address
The BOOTP server looks up the client’s MAC address in ts BOOTP table
The BOOTP server responds with
Client’s IP address
Server IP address
Server’s host name
Default router IP address

24. Dynamic Host Configuration Protocol (DHCP)
Application Layer protocol
Developed by the IETF to replace BOOTP
Dynamically assigns IP addresses
Does not use an IP address table like BOOTP
Does require a DHCP server to be configured
Reasons to use DHCP
Reduce management time on assigning and planning IP addresses
Reduce potential errors
Enables flexibility in client’s location
Makes IP addressing transparent to users

25. DHCP Leasing
Client request an IP address in a UDP DHCP discover packet - broadcast message
All DHCP servers on the network get the broadcast
All DHCP servers respond with an available IP address and reserves this IP information so that other clients can’t get it
The response message contains
The IP address
Subnet mask
IP address of the DHCP server
Lease duration
The client accepts the first IP address it receives
And responds with another broadcast message confirming the IP address
All other DHCP servers receive the message and release their IP addressed reserved for the client back to their DHCP pool

26. Automatic Private IP Addressing (APIPA)
Windows OS feature that assigns an IP address in the range of – and a subnet mask of
Allows communication only with nodes on the same LAN and hare automatically assigned an address in the APIPA address range
Used when DHCP services are temporarily unavailable
When DHCP services are restored the APIPA address is released

27. IPv6 Advantages over IPv4
More efficient header than IPv4
Better security
Better prioritization provisions
128 bits long increase amount of addresses to 296 (4 billion x 4 billion x 4 billion)
Expressed in 8 hexadecimal 16 bit fields separated by a (:)
Example – F:F:0:0:0:0:3012:0CE3
Can be written in shorthand – all multiple fields that have a value of 0 can be abbreviated with a (::)
IPv6 Loopback is 0:0:0:0:0:0:0:1
Shortened IPv6 Loopback is ::1

28. IPv6 – Unicast, Multicast, Anycast
Unicast – an address that represents a single interface – Prefix: FEC0 or FE80
Multicast – represents multiple interfaces normally on multiple devices…point-to- multipoint – Prefix: FF0x where x is a number that corresponds to a group scope ID – global multicast prefix : FF0E
Anycast – represents any one interface from a group of interfaces and any interface in that group can act on the message

29. Sockets
Sockets represent a single connection between two network applications. A socket is the process port number and the host machines IP address
An example is The Telnet port number, 23, and the host machines IP address with the port number following the IP address and a colon (:)
The above example is written as follows :
:23

30. Click Here for Well Known Port List
Ports
Simplifies TCP/IP and ensures that data transmitted is transmitted to the correct application
Port numbers range 0 to
Well known ports range from 0 to 1023
Registered ports range to 49151
Dynamic or Private ports range to
Click Here for Well Known Port List

31. Hostnames and Domain Names
A hostname is a specific name pointing to a specific device
A domain name is identifies a domain. A domain name is usually associated with some type of organization
Is represented by character strings called label
Each label represents a level in the domain naming hierarchy and is separated with dots
An example is
“.edu” is the top-level domain
“.ctcd” is the second-level domain
“www” is the third-level domain
Fully Qualified Domain Name (FQDN) the hostname followed by the domain name separated with a dot “.”

32. Typical Domain Tree

33. Host Files Predecessor to DNS An ASCII text file called HOSTS.TXT
Mapped host names to IP addresses
Used in early networks when they were small
Not practical in large networks or the Internet

34. Domain Name System (DNS)
Hierarchal system developed in the mid 1980s that gave a more automated approach to domain names than the HOSTS.TXT file
Also known as Domain Name Service
Relies on global DNS servers
All servers are hierarchically related to 13 root servers
Because it is distributed, it cannot fail catastrophically
Divided into 3 components
Resolvers – any host on the Internet that needs to look up domain name information
Name servers – also called DNS servers contain databases of associated names and IP addresses and provide this information to the resolvers
Namespace – refers to the database of Internet IP addresses and their associated names

35. Dynamic DNS (DDNS)/Zero Configuration (Zeroconf)
If IP addresses change frequently DNS becomes unmanageable
DDNS is a for-fee service that a service provider runs on the user’s computer that informs the service provider of an IP change
The service provider’s server launches a routine that updates the DNS servers
Zeroconf
A collection of protocols that simplify the setup of nodes on a TCP/IP network
IPv4 Local Link (IPv4LL) is a protocol that automatically assigns IP addresses on locally connected nodes

36. More Application Layer Protocols
Telnet – terminal emulation protocol used to logon to remote hosts using TCP/IP suite
File Transfer Protocol (FTP) – used to send and receive files via TCP/IP
Trivial File Transfer Protocol (TFTP) – Simplified transfer of files using UDP
Network Time Protocol (NTP) – Synchronizes clocks on computers on a network
Network News Transfer Protocol (NNTP) – Facilitates the exchange of news group messages
Packet Internet Groper (Ping) – a utility that verifies that TCP/IP is working, and configured correctly

37. End of Presentation
For more information on this lesson, See Chapter 4 in the text book or the Professor
**All Slides and graphics were produced by Professor Patrick Hughes**