DISCUSS TCP IP Model & Address in TCP IP.

TCP/IP PROTOCOL SUITE:

The layers in the TCP/IP protocol suite do not exactly match those in the OSI model. The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application. However, when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application.

Topics discussed in this section:

• Physical and Data Link Layers
• Network Layer
• Transport Layer
• Application Layer

TCP/IP and OSI model:

ADDRESSING:

Four levels of addresses are used in an internet employing the TCP/IP protocols: physical, logical, port, and specific.

• Physical Addresses
• Logical Addresses
• Port Addresses
• Specific Addresses

Addresses in TCP/IP:

Relationship of layers and addresses in TCP/IP

Physical addresses

In the above diagram a node with a physical address, 10 sends a frame to a node with physical address 87. The two nodes are connected by a link (bus topology LAN). As the figure shows, the computer with physical address 10 is the sender, and the computer with physical address 87 is the receiver.

IP addresses:

The above example shows a part of the internet with two routers connecting three LANs. Each device (computer or router) has a pair of addresses (logical and physical) for each connection. In this case, each computer is connected to only one link and therefore has only one pair of addresses. Each router, however, is connected to three networks (only two are shown in the figure). So each router has three pairs of addresses, one for each connection. 

Port addresses:

The Above Example shows two computers communicating via the Internet. The sending computer is running three processes at this time with port addresses a, b, and c. The receiving computer is running two processes at this time with port addresses j and k. Process and in the sending computer needs to communicate with process j in the receiving computer. Note that although physical addresses change from hop to hop, logical and port addresses remain the same from the source to destination. 

The physical addresses will change from hop to hop, but the logical addresses usually remain the same.

The physical addresses change from hop to hop, but the logical and port addresses usually remain the same.