1. Network Layer
IP Address

2. Addressing the Network: IPv4
IPv4 Addresses

3. Anatomy of an IPv4 Address
Each device on a network must be uniquely identified at the Network layer.
For IPv4, a 32 bit source and destination address is contained in each packet.

4. IPv4 Addressing Structure

5. Anatomy of an IPv4 Address
Dotted Decimal
Network
Host
Octet
32 bit Address

6. Binary to decimal and Vice Versa

7. Binary to Decimal

8. Decimal to Binary

9. Anatomy of an IPv4 Address
1.2
2.2
1.1
2.1
1.3
3.1
3.2
To identify a path or "route" through a network, the address must be composed of two parts:
Network portion
Host portion

10. Anatomy of an IPv4 Address
IP Address
192.
168. 1. 2
Binary IP Address
Network Portion:
Some portion of the high-order bits
A network can be defined as a group of hosts that have identical bit patterns in the network address portion of their addresses.

11. Anatomy of an IPv4 Address
IP Address
192.
168. 1. 2
Binary IP Address
Host Portion:
A variable number of least significant bits that are called the host portion of the address.
The number of bits used in this host portion determines the number of hosts that we can have within the network.

12. Anatomy of an IPv4 Address
How do we or devices identify the network part or the host part?
Answer: For us :Using the “Prefix Mask”.
/24 Means that the first 24 bits are the network portion. The last 8 bits are the host portion.

13. Anatomy of an IPv4 Address
Answer: For devices Using the “subnet mask”.

14. Prefix or Subnet Mask
The Prefix Mask and the Subnet Mask are different ways of representing the same information.
Prefix Mask of /24 or a subnet mask of
Prefix Mask of /16 or a subnet mask of
Prefix Mask of /8 or a subnet mask of

15. Subnet Mask IP Address: 10.24.36.2 / 8 Subnet Mask?
IP Address: Prefix Mask?
IP Address: Prefix Mask?
IP Address: Prefix Mask?
IP Address: Prefix Mask?
IP Address: Prefix Mask?

16. ANDing
Inside data network devices, digital logic is applied for their interpretation of the addresses.
AND is used in determining the network address.
0 AND 0 = 0
1 AND 0 = 0
1 AND 1 = 1
0 AND 1 = 0 A B
Result 1

17. Network and Host Part IP Address 135.15.2.1 255.255.0.0 A B Result 11
Decimal
Binary
IP Address
Subnet Mask
Network

18. ANDing –What is in our network?

19. Reasons to Use AND
Routers use the ANDing process to determine the route a packet will take.
The network number of the destination address is used to find the network in the routing table.
The router determines the best path for the frame.
Decimal
Binary
IP Address
Subnet Mask
Network

20. Reasons to Use AND
The source device uses the ANDing process to determine if the packet is to be sent to the default gateway.
If the destination network is the same as the network where the PC resides, the packet is sent directly to that host.
If the destination network is different, the packet is sent to the default gateway.
Decimal
Binary
IP Address
Subnet Mask
Network

21. 3 Types of Address Every network has: Network address – the first one
Broadcast address – the last one
Host addresses – everything in between

22. Types of Addresses

23. Network Address /24
Network Address
192
168 10
Broadcast Address
255
Host Address 1
All hosts in the network will have the same network bits.
Cannot be assigned to a device.
Each host bit in this address will be 0.

24. Broadcast Address Cannot be assigned to a device.
Network Address
192
168 10
Broadcast Address
255
Host Address 1
Cannot be assigned to a device.
Each host bit in this address will be 1.

25. Host Address
Network Address
192
168 10
Broadcast Address
255
Host Address 1
The unique address assigned to each device on the network.
Addresses through

26. Network Prefix is not always /24

27. Calculating Network, Host and Broadcast Addresses

28. Special Addresses

29. Unicast, Multicast, Broadcast
Unicast – a message addressed to one host
Broadcast – a message addressed to all hosts on a network. Uses network’s broadcast address or locally
Multicast – a message addressed to a group of hosts. Uses an address starting

30. Unicast and Multicast Examples of Multicast Application
Video and audio broadcasts
Routing information exchange by routing protocols
Distribution of software
News feeds

31. Broadcast Limited Broadcast Directed Broadcast
For a host outside of the network to communicate with the hosts within the /24 network, the destination address of the packet would be
A directed broadcast is sent to all hosts on a specific network.
he limited broadcast is used for communication that is limited to the hosts on the local network. These packets use a destination IPv4 address Routers do not forward this broadcast.

32. Range of IPv4 Addresses

33. Public and Private Addresses

34. Private IP addresses
Unrestricted use on private networks. Not routed across the Internet.
The ranges are:
– ( /8)
– ( /20)
– ( /24)

35. Public IP addresses Routed over the Internet
Master holder is IANA ( Internet Assigned Numbers Authority)
Assigned to regional registries and then to ISPs
ISPs allocate them to organisations and individual users
Use is strictly controlled as duplicate addresses are not allowed

36. Network Address Translation (NAT)
A large number of hosts on a network use private addresses to communicate with each other.
The ISP allocates one or a few public addresses.
NAT allows the hosts to share the public addresses when they want to use the Internet

37. Routing through NAT
Inside Private
Outside Public
Translation of Private IP address to Public IP address.
The translation process uses an internal translation table.

38. How Does NAT Work?
Send
R2: I have a packet for the outside network. I must translate the IP address. DA SA DA SA

39. How Does NAT Work? Receive
R2: I have a packet for the inside network. I must translate the IP address. DA SA DA SA

40. Dynamic Mapping and Static Mapping
NAT Table
Inside Local
Inside Global
Dynamic Mapping:
Mapping of local addresses dynamically to a pool of global addresses.
The hosts able to use NAT is limited by the number of addresses in the range.
If you have allocated 6 public addresses for NAT, any 6 users can use NAT simultaneously.
The NAT device dynamically assigns an address when a request is received. When a session ends, the address is returned to the pool for another user.

41. NAT Overload Port Address Translation (PAT): 209.165.200.226 SA DA
:1555
:80 SA DA
:1555
:80 SA DA
:1331
:80 SA DA
:1331
:80

42. NAT Overload Port Address Translation (PAT): 209.165.200.226 SA DA
:80
:1555 SA DA
:80
:1555 SA DA
:80
:1331 SA DA
:80
:1331

43. NAT Overload Port Address Translation (PAT): NEXT AVAILABLE PORT
:1444
:1444

44. Special IPv4 Addresses Default Route : Loopback Address :
“all addresses” in default route.
Hosts cannot be given addresses starting 0.
( /8) address block.
Loopback Address :
Hosts use this address to direct traffic to themselves.
Hosts cannot be given addresses starting 127.

45. Special IPv4 Addresses Link Local : TEST-NET
Automatically assigned to the local host by the operating system in environments where no IP configuration is available.
( /16 block)
TEST-NET to
set aside for teaching and learning purposes.
Unlike the experimental addresses, network devices will accept these addresses in their configurations.

46. Special IPv4 Addresses

47. Reserved and Special Purpose Addresses
Type
Block
Range
Network
1 per network
Broadcast
Multicast /4 –
Default Route /8 –
Loopback /8 –
Link-local
/16 –
Test-net
/24 –
Private /8
/12
/16 – – –

48. Legacy IPv4 Addresses-Classful

49. Classful addressing Easy to work out but very wasteful.
Routers and hosts still assume class subnet masks by default
Class A /
Class B /
Class C /

50. Planning to address the network

51. Assigning Addresses Static addressing
address is configured by an administrator
Servers, printers, routers, switches need static addresses

52. Assigning Addresses Dynamic addressing
address is allocated automatically by DHCP by leasing addresses from a pool.
Dynamic addressing is best for workstations

53. Assigning Addresses to other devices

54. Who Assigns IP Addresses?

55. Testing

56. Testing the Network -Ping
For testing IP connectivity between hosts.
Ping sends out requests for responses from a specified host address.
Uses a Layer 3 protocol, called ICMP (Internet Control Message Protocol).

57. Ping
Sends Echo request datagram, receiver responds with an ICMP Echo Reply datagram.
For each packet sent, ping measures the time required for the reply.

58. Testing the Local Stack

59. Testing Connectivity to the local network.

60. Testing Connectivity to Remote LAN

61. Example: Testing Local Stack

62. Testing Default Gateway

63. Testing Remote Network

64. Internet Control Messaging Protocol (ICMPv4)
ICMP is the messaging protocol.
As IPv4 is not a reliable protocol.
ICMP send messages to provide feedback, not to make IP reliable.
ICMP messages are not required and are often not allowed for security reasons.

65. Types of ICMP Messages ICMP messages that may be sent include:
Host conformation
Unreachable Destination or Service
Time exceeded
Route redirection
Source quench

66. Traceroute/Tracert
Traceroute (tracert) is a utility that allows us to observe the path between these hosts.
The trace generates a list of hops that were successfully reached along the path.
An asterisk (*) is used to indicate a lost packet.

67. Tracert Example

68. IPv6

69. IPv6
128-bit hierarchical addressing - to expand addressing capabilities
Header format simplification - to improve packet handling
Improved QoS mechanisms and security.
IPv6 is not merely a new Layer 3 protocol - it is a new protocol suite.

70. IPv6 Address