Introduction to TCP/IP Essentials 1--TCP/IP Basics

1th Chapter the concept of TCP/IP

TCP/IP refers to the set of network protocols used for the Internet and many other networks.

 

TCP/IP Features:

Ø logical addressing-the physical address (MAC address) is a unique and permanent address for each network adapter, totalling 48bit. In TCP/IP, a logical address is called an IP address and is used to locate the address of a computer or other networking device on a TCP/IP network and is configured through network protocol software. The logical address and specific hardware physical address are converted to each other using the ARP and RARP protocol.

Ø routing-completed by the router, it can forward data through the logical address.

Ø name Resolution--The mapping of domain name to IP address is called name resolution. A special computer called a domain Name server stores tables that show how to convert domain names and IP addresses, providing domain names and IP address mappings for computers that register DNS on your network.

Ø error control and flow control--TCP/IP Transport Layer defines error checking, flow control and notification functions for data through the TCP protocol. In the low-level Protocol of TCP/IP network access layer, part of system error control is also formed.

Ø application Support--in TCP/IP, the interface between the Protocol software and the application is called the port through the logical channel of the system. Each port has a number to identify it.

2nd Chapter TCP/IP working mode

TCP/IP protocol System Four-layer model:

Ø Network access layer: Provides interface with physical network. The format of data is set for transmission media, the data is addressed according to physical address, and the transmission of data in physical network is provided with error control.

Ø The Internet layer: provides hardware-independent logical addressing, allowing data to be passed between subnets with different physical structures. Provides routing capabilities to reduce data traffic and support data delivery over the Internet. Implements transformations of physical addressing and logical addressing.

Ø Transport Layer: Provide Internet Data flow control, error control and validation, provide interface for network application.

Ø Application layer: Provides network troubleshooting, file transfer, remote control and Internet operation applications, and also supports APIs to enable programs written for specific operating systems to access the network.

 

TCP/IP and the OSI model:
The OSI model divides the application layer function into 3 layers: Application layer, presentation layer and session layer, dividing the function of the network access layer into the data link layer and the physical layer.

Packets have different forms and names at each level:

Ø the data packets generated by the application layer are called messages.

Ø the packet generated by the transport layer encapsulates the application-layer message and, if it comes from a TCP protocol, is called a fragment, or datagram if it comes from a UDP protocol.

Ø the data packet of the Internet layer encapsulates the data of the transport layer, called the datagram.

Ø data packets in the network access layer encapsulate the datagram (which may be decomposed), called frames. A frame is transformed into a bit stream by the lowest layer in the access layer.

TCP/IP Network Overview

Ø Application layer: Including network Service, application interface and network application and tools.

Ø Transport Layer: Two major protocols-reliable, connection-oriented TCP protocol and unreliable, connectionless UDP protocol.

Ø the Internet layer: mainly IP protocol, there are ARP and RARP protocol.

Ø Network access layer: Includes fts/fddi/ppp/802.11 Wireless/Ethernet and physical network.