Saturday, October 1, 2011

TCP/IP Protocol Suite and IP Addressing


TCP/IP Protocol Suite 

The U.S. DoD created the TCP/IP reference model because it wanted a network that could survive any conditions.TCP/IP model has become the Internet standard.
Application Layer

Handles high-level protocols, issues of representation, encoding, and dialog control
IP as a Routed Protocol


IP is a connectionless, unreliable, best-effort delivery protocol.


As information flows down the layers of the OSI model; the data is processed at each layer.


IP accepts whatever data is passed down to it from the upper layers.
Packet Propagation and Switching Within a Router
IP Address

An IP address is a 32-bit sequence of 1s and 0s. 

To make the IP address easier to use, the address is usually written as four decimal numbers separated by periods.  

This way of writing the address is called the dotted decimal format.  

Every IP address has two parts:  
  • Network 
  • Host 
IP addresses are divided into classes A,B and C to define large, medium, and small networks.

The Class D address class was created to enable multicasting.
IETF reserves Class E addresses for its own research.
Reserved IP Addresses
Certain host addresses are reserved and cannot be assigned to devices on a network.
An IP address that has binary 0s in all host bit positions is reserved for the network address.
An IP address that has binary 1s in all host bit positions is reserved for the broadcast address.
Subnet Mask Address
nDetermines which part of an IP address is the network field and which part is the host field.
nFollow these steps to determine the subnet mask:
u1. Express the subnetwork IP address in binary form.
u2. Replace the network and subnet portion of the address with all 1s.
u3. Replace the host portion of the address with all 0s.
u4. Convert the binary expression back to dotted-decimal notation.
Subnetting example

IP Private Addresses
No two machines that connect to a public network can have the same IP address because public IP addresses are global and standardized
Private IP addresses are a solution to the problem of the exhaustion of public IP addresses. Addresses that fall within these ranges
are not routed on the Internet backbone: 

Connecting a network using private addresses to the Internet requires the usage of NAT