Lesson 2	TCP/IP protocol suite
Objective	Define the components of TCP/IP protocol suite.

TCP/IP Layer

TCP/IP operates on a wide variety of physical networks and can be scaled to suit small to large networks. IP is the protocol used for communications on public networks such as the Internet. If your business plans to be connected to the Internet, it must use TCP/IP as its LAN protocol. TCP/IP has become the LAN protocol of choice for businesses large and small because virtually all businesses need to be connected to the Internet.
In order to effectively design a TCP/IP network infrastructure, you need to consider the following:

The components of the TCP/IP protocol suite
The design decisions influencing a TCP/IP solution
The features and functionality provided by TCP/IP in Windows® 2000

This lesson will examine the TCP/IP protocol suite. Forthcoming lessons will look at the other essential aspects to designing with TCP/IP.

TCP/IP Protocol Suite

The TCP/IP suite of protocols allows the design of a logical peer network by using an underlying physical network infrastructure. These vendor-independent protocols can be used to implement IP networks ranging from small local area networks (LANs) to large enterprise networks. The following MouseOver shows the mapping of the Open Systems Interconnection (OSI)^[1] seven-layer model to the TCP/IP four-layer model, and the major components of the TCP/IP suite. We assume the OSI layer one and two infrastructure is in place for any design considerations in this module.

TCP/IP Protocol Suite

1) OSI Model 2) TCP/IP Model 3) TCP/IP Protocol Suite

OSI Model: This International Standards Organization (ISO) OSI model incorporates the following qualities. It is designed to establish data-communications standards that promote multivendor interoperability.
1. It consists of seven layers, with a specific set of network functions allocated to each layer and guidelines for implementation of the interfaces between layers.
2. It specifies the set of protocols and interfaces to implement at each layer.
TCP/IP Model: TCP/IP is based on a four-layer reference model. All protocols that belong to the TCP/IP protocol suite are located in the top three layers of this model. Each layer of the TCP/IP model corresponds to one or more layers of the seven-layer OSI reference model proposed by the ISO.
TCP/IP Protocol Suite: TCP/IP represents only two of the protocols that are commonly used on IP-based networks. TCP/IP is often referred to as a protocol suite because there are a number of different protocols used on IP-based networks that provide different network services. When taken together, they represent a "suite," or group, of protocols.
ARP: (Address Resolution Protocol): performs IP address-to-Media Access Control (MAC) address resolution for outgoing packets. As each outgoing IP datagram is encapsulated in a frame, source and destination MAC addresses must be added. Determining the destination MAC address for each frame is the responsibility of ARP.
IGMP: (Internet Group Management Protocol): helps communicate multicast group membership information to a Multicast Group Manager. It uses Windows sockets to send and receive IGMP traffic. This protocol supports forwarding of IGMP messages over Windows 2000 routers.

(IETF) Internet Engineering Task Force

TCP/IP Protocol Suite
The (IETF) Internet Engineering Task Force continues to revise and improve the TCP/IP suite of protocols. Microsoft continuously updates the TCP/IP implementation to comply with the latest IETF standards. The next lesson provides a global view of the considerations for designing a TCP/IP solution.

[1]Open Systems Interconnection (OSI): A framework designed by the International Standards Organization for which new network protocols to based themselves.