1. DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY
TCP/IP and IP addressing
We are going to introduce TCP/IP and IP addressing. Internet is developed by US DoD (Department of Defense). TCP/IP is an open standard under direction of Internet Architecture Board (IAB) and Internet Engineering Task Force (IETF).

2. Internet and TCP/IP
Internet is a global network of interconnected computers, enabling users to share information along multiple channels.
Majority of widely accessible information on the internet consists of inter-linked hypertext documents and other resources of the World Wide Web (WWW).
The Internet Protocol Suite (commonly known as TCP/IP) is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard.
TCP/IP is an open standard under direction of Internet Architecture Board (IAB) and Internet Engineering Task Force (IETF).
RFC (Requests For Comments) is a kind of protocol to develop TCP/IP standards

3. TCP/IP model Application Transport Internet Network Interface
Presentation
Session
Transport
Network
Data Link
Physical
TCP/IP is the internet protocol and it is presented in layer model for easy understanding. The main models are DoD (Department of Defense) 4 layers and ISO (International Standard Organization) 7 layers model. Most popular model is the OSI/ISO 7-layer model
The Application Layer can include things like File Transfers, and display formatting. HTTP is an example of an Application Layer protocol.
Presentation Layer: Other than data sent/accepted to/from the application layer and Session Layer, this layer is reserved for certain kinds of data manipulation or consistent data types being encapsulated for transmission. Translations could possibly be made between ASCII and Unicode or even EBCIDIC if hexadecimal values for letter were being transmitted.
Deal with creating a session, transmission of data, and then tear down of the created session. Sessions are created and terminated at the request of the Presentation Layer as it has data needing to be passed on to a different location. Another service that is offered as a part of the Session Layer might include data synchronization. Checksums may also be included at the Session Layer as a part of data synchronization.
Transport Layer must create a connection of the type needed by the Session Layer for each connection requested by the Session Layer.
Network layer is responsible for IP addressing, routing
Data link layer is packaging bits into cells, or frames.
Physical layer is responsible for moving bits across a shared media between two points.

4. TCP/IP protocol suite
Telnet, HTTP, HTTPS, FTP, SNMP, POP3, IMAP, etc, etc are protocols working in Application layer.
ARP, proxy ARP, RARP, ATM, Frame Relay, SLIP and PPP are all working in network access layer

5. TCP/IP Network Access Layer
Defines how computers and network devices should access a physical medium to send bits to another computer.
Network Access layer has two ISO OSI layers, layer 1 and 2 (Physical and Data Link)
IETF does not define any standard in this layer because other organizations define many standards. For instance, Ethernet is developed by IEEE.
PDU (Protocol Data Unit) is bit in layer 1 (Physical) and frame in layer 2 (Data Link).
FDDI, Ethernet, Fast Ethernet, ARP, proxy ARP, RARP, ATM, Frame Relay, SLIP and PPP are all working in network access layer.
This layer also work with physical (MAC) address
Some people may call it Network Interface layer

6. TCP/IP Internet Layer
Defines how to deliver data from one host to another on various physical networks:
Logical addressing
Routing and routing protocol
Main protocols: IP, ARP, RARP (Reverse Address Resolution Protocol), ICMP (Internet Control Message Protocol) and router protocols such as RIP (Routing Information Protocol) and OSPF (Open Shortest Path First).
PDU (Protocol Data Unit) is packet in layer 3
The layer will specify logical rules to work together with different physical networks. We will introduce IP Addressing and routing basic in next slides.

7. ICMP (Internet Control Message Protocol)
ICMP can report error for diagnostic or routing control purpose. Two key commands are used to test connectivity:
PING (ICMP echo request and reply command)
Tracert is Microsoft version command while Cisco uses traceroute to display routing path while testing connectivity.
Details of ICMP would be beyond this course. But, please keep in mind that

8. TCP/IP Host-to-Host (Transport) Layer
Two main protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol)
TCP provides reliable data delivery service with end-to-end error detection and correction.
UDP provides low-overhead, connection less datagram delivery services.
Application programmers can choose which protocol to use.
PDU (Protocol Data Unit) is segment in layer 4 (Transport)
In the encapsulation process, each layer adds header based on that received from higher layer.

9. TCP and UDP The two important transport layer protocols:
They help to transfer data from one application process on one computer to the correct application process on another computer.
TCP (Transmission Control Protocol)
Connection-oriented protocol, more reliable and slower.
UDP (User Datagram Protocol)
Connection-less, faster, simpler and not reliable (no error checking).
It is an essential to know the difference between TCP and UDP. Another similar case is the difference between FTP (secured but slower than TFTP) and TFTP (Trivial File transfer Protocol) (faster without authentication)

10. TCP and UDP comparison Features TCP UDP Flow control and windowing YesNo
Connection-oriented
Error recovery
Segmentation and reassembly of data
In-order delivery of data
Identifying application using port numbers
This chart can help to understand difference of TCP and UDP

11. TCP/IP Application Layer
Offer interface to deal with various applications:
File transfer: FTP, FTP, NFS
SMTP, POP3, IMAP
Remote login: Telnet
Network Management: SNMP, DNS
Web browsing: HTTP, HTTPS
Application layer is not application.

12. Some protocols (1) FTP (File Transfer Protocol)
TFTP (Trivial File Transfer Protocol)
NFS (Network File System)
SMTP (Simple Mail Transfer Protocol)
LPD (Line Printer Daemon)
SNMP (Simple Network Management Protocol)
DNS (Domain Name Service)
DHCP (Dynamic Host Control Protocol)
TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)
IP (Internet Protocol)
It is good for you to remember full name and abbreviation of those protocols

13. Some protocols (2) ARP (Address Resolution Protocol)
RARP (Reverse Address Resolution Protocol)
POP3 (Post Office Protocol V3)
IMAP (Internet Message Access Protocol)
RIP (Routing Information Protocol)
OSPF (Open Shortest Path First)

14. IPV4 address
1. IP address must be unique in the network (Public IP address must be unique in internet and private IP address must be unique in the internal network)
2. The format is xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx (totally 32-bit).There are public IP address used in Internet and private IP address used in company/organization internal networks.
3. As 8 bits binary can present in decimal, IP address could be (and usually is) presented as (You must not see such IP address )
4. Network mask is to divide the IP address into two logical sections (network ID and host ID)

15. Network Mask
IP address has both Network ID (network address) and Host ID (host address). If the value is 1 in the mask, it means the corresponding bit in the IP address is the network ID. If the value is 0, it means the corresponding bit is for the host ID. For instance, network musk is which equals to binary value The “1” section presents the network ID. So, would have the first octet 10 as network ID. If the network mask is , the network ID of would be because is in the mask.
We will give you more details to understand the calculation

16. Valid network mask Binary value Decimal value 00000000 10000000 128
128
192
224
240
248
252
254
255
Any other value would be invalid mask. It is impossible to have (204) as a mask value.

17. IP address class
Traditionally, the IP address was classified in classes:
Class A: network 1 – 126 with subnet mask (Initial bit starts as 0)
Class B: network 128 – 191 with subnet mask (Initial bit starts as 10)
Class C: network 192 – 223 with subnet mask (Initial bit starts as 110)
Class D: network 224 – 239 (Initial bit starts as 1110) for multicast IP address
Class E: network 240 – 255 (Initial bit starts as 1111) experimental use
The special network 0 and127 are not included in those official classical IP address is the loopback address which is used to test TCP/IP stacks.
Based on the slide, you should understand that is a class A IP address; is a class B and is a class C address.

18. Some basic rules In same network, no routing or router is required.
In same network, IP address must be unique to identify the computer or network host. In the internet, public IP address must be globally unique (we will introduce private IP address soon).
Router or routing is required between different networks.
In many contexts, default gateway and router are interchangeable used.

19. Power calculation of 2 The powers of 2 Decimal value Binary Value 2^01
2^1 2
2^2 4
2^3 8
2^4 16
2^5 32
2^6 64
2^7
128
2^8
256
2^9
512
2^10
1024
2^11
2048
2^12
4096
2^13
8192
Put the 0 on the right side of the 1 according to the power number. For instance, 2^3. We put 3 “0”s at the right side of 1  Without calculation, we can say that 2^11  (11 “0”).

20. Network address and Broadcast address
Network address is also called network ID. It is the part defined by subnet mask. For instance, network musk is which equals to binary value The “1” section presents the network ID. So, would have the first octet 10 as network ID. Network ID is to have all 0 in the host ID section.
If the broadcast address is the destination address of a packet, it would be sent to all hosts in the same network. Broadcast address is to have all 1 in the host ID section. For instance, broadcast address of /8 is
Question:
What would be the broadcast address of /24? (The /24 means 24 bits network mask leading to decimal value )
What could be the broadcast address of /16? (The /16 means 16 bits network mask leading to decimal value )

21. Unicasts, Multicasts, and Broadcasts
– Packet travels from one host to another specific host.
Multicasts:
– Packet travels from one host to a select number of other hosts.
– Supports voice and audio broadcasts, news feeds, distribution of
software, re-imaging clients off peak times.
Broadcasts:
– Packet travels from one host to all hosts on the local network.

25. Broadcast Address
All of the bits in the host portion of the broadcast IP address ends with binary 1s.
– For network •
– The broadcast address is
So in binary-----

26. Valid host number Class Size of host id (bytes) Size of host id (bits)
If the host id bits are all 0 in IP address, it presents the network address; If the host id bits are all 1 in IP address, it presents the broadcast address of the network. Valid host cannot have those 2 special (reserved) IP address.
Valid host number is: 2^(number-of-host-bits) – 2
Computer operating systems usually would not treat as a valid host IP address. For the same reason, it cannot use as the computer IP address.
Class
Size of host id (bytes)
Size of host id (bits)
Number of hosts per network A 3 24
2^24 – 2 = 16,777,214 B 2 16
2^16 – 2 = 65,534 C 1 8
2^8 – 2 =254
If the host id bits is 6 which could be in our class C subnet calculation, the host number would be 2^6-2 = = 62;
If the host id bits is 13 which could be in our class B subnet calculation, the host number would be 2^13-2 = = 8190;

27. Network number calculation
The tricky part is that there are fixed bits in network ID of all classes. Class A has 0 in first bit all the time (0-126). Class B always has 10 in the first two bits. Class C has 110 as fixed bits.
Class
Size of network id (bytes)
Size of network id (bits)
Number of fixed bits at beginning
Number of network bits that vary
Number of networks A 1 8 7
2^7 – 2 = 126 B 2 16 14
2^14 – 2 = 16,192 C 3 24 21
2^21 – 2 = 2,097,152

28. Subnet
Subnet is to logically divide your network into many sub networks.
In the same subnet, traffic is “local” and not gateway (router) is required. Network hosts would use ARP table for the MAC address of the destination machine and send the packet to it accordingly. If it is not local, packets would be forwarded to default gateway for future routing (redirecting).
In addition, the broadcast would be limited to the small subnets leading to less “noise” in the network traffic.
You can also use subnet to logically specify hosts for different departments. (for security control, connection, asset management, etc, etc)
Subnet is to use the classless network mask. The classful mask is 8 (class A), 16 (class B) and 24 (class C). Subnet mask could be any number such as 9 bits ( ),

29. Define subnet number
Subnet bits (“1”) can tell how many subnet could be produced by the mask. The formula is 2^(number of subnet “1” bits) - 2
Original classfull network mask:
Class A network has the form N.H.H.H, the default subnet mask is 8 bits long.
Class B network has the form N.N.H.H, the default subnet mask is 16 bits long.
Class C network has the form N.N.N.H, the default subnet mask is 24 bits long.
The additional subnet bits can generate subnet. For instance, You have an IP of with a subnet mask of 7 bits. How many hosts and subnets are possible?
There is additional 7 bits to the default subnet mask. The total number of bits in subnet are 16+7 = 23. This leaves us with =9 bits for assigning to hosts. 7 bits of subnet mask corresponds to (2^7-2)=128-2 = 126 subnets. 9 bits belonging to host addresses correspond to (2^9-2)=512-2 = 510 hosts.
Please be familiar with different subnet mask format.
Decimal style:
Binary style:
CIDR -- Classless InterDomain Routing format: /xx such as /8, /11 in which the number means how many bits would be 1. The /8  

30. Define host number in each subnet
Subnet bits (“0”) can tell how many host could be contained in each subnet. The formula is 2^(number of host “0” bits) - 2
Original classfull network mask:
Class A network has the form N.H.H.H, the default host mask is 24 bits long.
Class B network has the form N.N.H.H, the default host mask is 16 bits long.
Class C network has the form N.N.N.H, the default host mask is 8 bits long.
The additional subnet bits can generate subnet. For instance, You have an IP of with a subnet mask of 7 bits. How many hosts and subnets are possible?
There is additional 7 bits to the default subnet mask. The total number of bits in subnet are 16+7 = 23. This leaves us with =9 bits for assigning to hosts. 7 bits of subnet mask corresponds to (2^7-2)=128-2 = 126 subnets. 9 bits belonging to host addresses correspond to (2^9-2)=512-2 = 510 hosts.
Please be familiar with different subnet mask format.
Decimal style:
Binary style:
CIDR -- Classless InterDomain Routing format: /xx such as /8, /11 in which the number means how many bits would be 1. The /8  

31. Routing
If all traffics are in the same LAN (subnet), no routing is required. The computers talk to each other over network cable directly.
In different LAN (subnet), the packet sent from sender must be “redirected” (routed) to another network in which the recipient is located.
Router will use routing protocol to do the routing job between different networks. In same LAN (subnet), no routing is required. If the LAN is divided into different subnets, routing is necessary.
To show a routing table in your Windows computer:
Start  Cmd  Ok  run command “route print”
More details would be introduced next class.

32. Cisco 2610 interfaces (optional)
Console: management port. Console cable is required.
Aux Port: phone modem connection for remote access
Ethernet port to connect to LAN or any other network.
Serial port is usually used in WAN connections.

33. Public IP address
IANA (Internet Assigned Numbers Authority has the ultimate authority. It authorizes member organizations to assign registered unique IP address to users. For instance, ARIN (American Registry for Internet Numbers) is in charge of assigning IP address in US.
In general, each computer needs a public IP address to identify itself and access Internet.
Your service request (demand of public IP address) would be directed to local agents who are usually ISPs.

34. Private IP address
Certain blocks are reserves as private IP address used in company / organization internal networks. More computers could have “unique” IP address in IPV4.
Class
Range of IP address
Range of Network number
Default network mask
Total number of networks A – –
/8 ( ) 1 B –
/12 ( ) 16 C –
/16 ( )
256
Class A private: / 8 means the subnet mask is
Class B private: / 12 means the subnet mask is
Class C private: /16 means the subnet mask is
Thus, it is possible for many companies / organizations using same network address internally. (For instance, could be used for computer Tom in company Apple and by computer Jerry in company Boss) But, again, the potential duplicated addresses are used internally.

35. NAT (Network Address Translation)
Allow 65,535 user connections with the same public (registered) IP address.
Enable multiple users (computers) sharing single internet connection.
The computers may have internal private IP address. But, they can have public identifier via the public IP address.
The solution is to use NAT map to associate user connection from internal private IP address and public IP address. The NAT map is beyond this course. But, port number is used to have the many-to-many mapping.
IPV4 may not be able to offer all international users sufficient unique identifiers in the internet.
Each user can make multiple connections visiting different web sites and downloading/uploading files. If each user has 5 connections, total user connections would be 100 for 20 users.

36. NAT Illustration (optional)

37. IPV6 128 bits address format 6 octets Usually presented in hex
May support 10^30 IP addresses (IPV4 only supports 4,294,467,295 IP addresses)
Still not in final implementation
NOT interoperable with IPV4
Old equipments do not support IPV6 addressing and routing.

38. IP address assignment IP address could be assigned by: Static
User manually assign the IP address, mask, default gateway and DNS.
Dynamic (automatically) by DHCP (Dynamic Host Control Protocol) server
No need to do any configuration. Enable DHCP client and the computer (client) would get IP address and other info from DHCP server. (Network Administrator does need to do configuration on server side.)
When you assign IP address, you will need to specify IP address, subnet mask, default gateway IP address and DNS server IP address

39. Compare static and DHCP
Good for large network
Yes No
Client side configuration
Server side configuration
Move whole network address to another number blocks (change to )
Can reuse the IP address by other computers
Security control
Average
High
In general, network administrator only assign static IP address to server, router, switch or gateway. Other users’ computers usually use DHCP service. Usually, only VIPs have reserved room. Other audiences will sit in public seats.

40. ARP (Address Resolution Protocol)
ARP table is to contain IP address and associated MAC address information.
To add or update ARP table:
Senders sends ARP Request (ARP broadcast) out.
Receiver returns ARP Reply (unicast) back.
RARP is to offer IP address against MAC address (reverse direction)
ARP broadcast is another typical broadcast which helps communication in the network.

41. ARP command
ARP command can be used to display, add and clear entries in ARP table:
Arp /? can display all options of the command:
arp –a
arp –s
arp -d
Proxy ARP is not popular at all. I would not cover it in the class. If you are interested, please read the book. If you have any question, I am willing to answer you in the class.

42. Question
Any question?
If you do not have question, please start subnet calculation.
What subnet mask would be if I want to have 10 subnets in /8?
What subnet mask would be if I want to have 20 hosts in each subnet in /24?
Do not forget the lab assignment.
Please dig out DHCP and DNS in the internet. If you have a Windows or Unix server, you can play around to setup DHCP and DNS services.
We will continue subnet next class.