Date post: | 14-Dec-2015 |
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First thing you need to know is that every
computer has an IP address
There are TWO ways in which a computer gets an IP address:
Static Method Dynamic Method
A computer administrator will manually set the IP address to the
machine
The Dynamic Host Control Protocol (DHCP) server is responsible for assigning IP
addresses to all computers on the network
IP Addressing
Different Types of IP Addresses
There are two different types of IP
addresses
Private
Personal computers are usually assigned private
IP, which is then connected to a router
with a public IP
Public
Servers typically use public IP addresses
Searching google.com
Your computer Your router/ domain name server
Google’s IP address
• A request is sent to the router to find out the IP address of the domain name
• Here is where the domain name is converted into it’s IP address
• Once the IP is known, the DNS server sends an HTTP GET request to Google’s particular IP
google.com
74.125.224.72
HTTP GET request
MAC addresses are added in the data link
layer before the packet heads to the
physical layer
In the network later, information related to
source & destination IP addresses are are
added and then are sent to the Data Link layer
Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
HTTP GET request
Packet
Packet
Packet
Requests are encapsulated in the
form of transport layer packets and
then are sent to the network layer
Post DNS Stage
Two protocols operate in the Transport Layer:
UDPTCPUser Datagram ProtocolTransmission Control Protocol
Ensures that the packet is not larger than the largest protocol data
unit in the path located between your computer
and the destination
Offers a limited amount of service
when messages are exchanged between
computers in a network that uses IP
The router searches it’s cache for the
packets host address, when found, it
forwards the packet to it’s destination
Packet
Your computer Router Destination
Packet
When the packet leaves your computer, the MAC Address of the router in
which your packet is being transferred to is used as the packets destination
MAC Address
The following slide will show the process that the packet goes through while traveling to it’s destination
HTTP GET Request is passed to the application listening on the
port
Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical LayerPacket
Packet
Packet
Packet
IP address checks and check-sum
verifications are done before passing to the
transport layer
The MAC address is checked to see if the
packet is at the correct destination