Ip addressing

IP Address
• A Unique, 32-bit address used by computers to
communicate over a computer network

Types of IP Address

Static Dynamic

Classful IP Addressing - I
• IP address structure consists of two addresses, Network
and Host
• IP address is divided into five classes

Classful IP Addressing - II
Byte 1 Byte 2 Byte 3 Byte 4

Class A Network ID Host ID

Class B Network ID Host ID

Class C Network ID Host ID

Class D Multicast Address

Class E Reserved for future use

Examples of Classful Addressing
• 14.23.120.8 - The first byte of the address
represents 14 which lies between 0 and 126,
hence Class A address.
• 134.11.78.56 - The first byte of address is
134 which lies between 128 and 191 hence
the address belongs to Class B.
• 193.14.56.22 - As first byte is 193 which is
between 192 and 223, hence the address
belongs to Class C.

Unicast, Multicast and Broadcast
Addresses
• Used to achieve communication on the Internet
• Unicast address uniquely identifies a host in a network
and belongs to class A, B and C
• Multicast address defines an address for a group and
belongs to class D
• A system on a multicast network can have more than
one class D multicast address
• Broadcast address allows user to send data packet to all
machines on a given network and is last address of that
network

Guidelines for using an IP Address
• All hosts located on same physical network segment must
have same network address.
• A unique host ID of the IP address must be allotted for each
host on the network segment.
• A network ID that starts with its first byte indicating 127
should not be used, as this value is reserved for loop back
functions.
• A network ID having all 1s in its host address field cannot be
used, as this represents a broadcast address for the local
network.
• A network ID having all 0s in the network address field cannot
be used for communication over Internet as this address
represents the default network address.

IP Subnetting
• Allows you to divide a network into smaller sub-networks
• Each subnet has its own sub-network address
• Subnet can be created within Class A, B, or C based
networks

Subnet Mask
• Specifies part of IP address used to identify a
subnetwork.
• Subnet mask when logically ANDed with IP address
provides 32-bit network address

Subnet Mask

AND
IP Address Operation Network Address

Default Mask
• Has predetermined number of 1s
• Class A, B and C contains 1s in network ID fields for
default subnet mask

Address Default Mask
Class (in Binary)
Class A 11111111.00000000.00000000.00000000
Class B 11111111.11111111.00000000.00000000
Class C 11111111.11111111.11111111.00000000

Classless IP Addressing
• Ruled out fixed size network address
• Network address can vary from 0-bit to 31-bit
• Uses Classless Inter-Domain Routing (CIDR) addressing
scheme
• CIDR address notation:

154.201.179.42/18
First 18 bits represent
network ID
IP address

Variable Length Subnet Mask (VLSM)
• Used by CIDR to allocate IP addresses to subnets
depending up on the requirement
• Allows network administrator to create variable size
subnets within a network
• Employs two different subnet masks at router which are
ANDed one after another to the address

Example of VLSM - I
• For example, if an organization is given a Class C
address and the organization needs to have five
subnets VLSM employs two subnet masks.
• If the IP address is 201.70.64.0, consider the first
subnet mask with 26 1s that is 255.255.255.192 or in
binary format
1111111.11111111.11111111.11000000
which provides four subnets having 64 addresses in
each subnet.

Example of VLSM - II
• Further, one of the subnet having 64 host addresses
is divided in two subnet having 32 hosts addresses by
applying a mask of 27 1s that is 255.255.255.224 or
11111111.11111111.11111111.11100000
to one of the subnet from the four subnets. Refer to
the figure in next slide.

Example of VLSM - III

201.70.64.0 – 201.70.64.63

201.70.64.64– 201.70.64.127

201.70.64.128 – 201.70.64.191

201.70.64.192 – 201.70.64.223

201.70.64.224 – 201.70.64.254

Special Addresses
• IP addresses which are never used on the public Internet

Types of Special
Address

Loop-back Link-Local
Private Address
Address Address

IPv6
• Latest version of IP addressing over IPv4
• Implements 128-bit network in contrast to 32-bit IP
address used by IPv4
• Address notation consists of 32 hexadecimal digits with
every 4 digits separated by a colon

Ping, Tracert and Path Ping
• Utility tools used for keeping track about hosts on the
network and network structure
• Ping (Packet Internet Groper) – Used by computer
network to test whether intended host is reachable
across IP network
• Tracert – Used by Windows operating system to increase
time-to-live (TTL) value of data packets sent
• Pathping – Provides useful information about network
errors, network latency and network loss at hops
between source and destination address

Host Addressing In Mobile IP - I
• Host cannot carry IP address from one network to
another
• IP address is valid only when the host is connected to a
particular network
• When a host moves from one network to another it
requires IP addressing structure to be modified
• To maintain network connectivity of host within new
network:
– Change IP address from one network to another
– Use two IP addresses

Host Addressing In Mobile IP - II
• To maintain network connectivity of host within new
network:
– Change IP address from one network to another - Provides
network connectivity for mobile host when it travels from
one network to another by changing IP address of mobile
host
– Use two IP addresses - Host uses home address when it is
in permanent home network and uses care-of-address
when it moves to foreign network

Agents in Mobile IP - I
• Mobile IP includes two
agents to make address
Agents
changes invisible to the
rest of the Internet

Home Foreign
Agent Agent

Agents in Mobile IP - II
• Home agent
– Involves a routing device attached to home network of
mobile host
– Transmitting data packet from host to mobile host

Packet
Home Foreign Mobile
Host
Agent Agent Host

 Foreign agent
 Usually a router that is attached to foreign network
 Receives packet sent by home agent and delivers
these packets to mobile host

Phases in Mobile IP
• While communicating with a remote host, a mobile host
has to undergo three phases

Inefficiency in Mobile IP
• Mobile IP sometime may provide with inefficient
communication which can be either severe or
moderate.
• Inefficiency may be caused due to:
– Double Crossing
– Triangle Routing

Ip addressing

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Ip addressing

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