Overview of network transmission protocols-lecture 1: Overview of transmission protocols

Network transmission protocol or communication protocol for short
Protocol) refers to the common language for computer communication. Currently, the most popular computer communication is network communication. Therefore, the "Transfer Protocol" generally refers to the transmission protocol for computer communication, such as TCP/IP and NetBEUI. However, the transfer protocol also exists in other computer forms of communication, such as communication between objects in object-oriented programming; communication between different programs in the operating system requires a transfer protocol, to ensure communication between both parties.

Network protocols are rules for transmitting and managing information on networks (including the Internet. For example, communication between people must follow certain rules, and mutual communication between computers must comply with certain rules. These rules are called network protocols.
A computer can communicate with other computers on the network only when it complies with the network protocol. Network protocols are generally divided into several layers to complete their own functions. Both parties can communicate with each other only at the same level. Common protocols include TCP/IP, IPX/SPX, and NetBEUI. IPX/SPX is usually used in the LAN .. If you access the Internet, you must add the TCP/IP protocol to the network protocol.

Let's briefly introduce the differences between different transmission protocols:

IPX/SPXInternet group Exchange/ordered group Exchange IPX/SPX (Internetwork Packet Exchange/Sequences Packet Exchange) is a communication protocol set of novell. What makes a clear difference with NetBEUI is that IPX/SPX is relatively large and has strong adaptability in complex environments. This is because IPX/SPX takes into account the network segment issue at the beginning of the design. Therefore, it has powerful routing functions and is suitable for large networks. When the client accesses the NetWare server, IPX/spx and its compatible protocols are the best choice. However, in non-Novell network environments, IPX/SPX is generally not used. IPX is mainly used to establish and maintain connections between network devices. SPX is an auxiliary protocol of IPX, mainly used to send messages by grouping and tracking groups, ensuring complete information transmission. Note: It is a communication protocol developed by Novell to adapt to the development of the network. It has strong adaptability, easy installation, and routing functions, which can realize communication between multiple network segments. IPX is responsible for data packet transmission, and SPX is responsible for data packet transmission integrity. In the mcrosoft NT operating system, NWLink is generally used.
IPX/SPX compatible protocol and NWLink NetBIOX IPX/SPX compatible protocol, that is, the NWLink protocol, which inherits the advantages of IPX/SPX Protocol and is more suitable for the Windows network environment. IPX/SPX protocols can be used in large-scale networks (such as Novell) and LAN game environments (such as anti-terrorism elites and Starcraft ). However, if the IPX/SPX protocol is not used in the Novell Network Environment, IPX/SPX compatibility protocol is used, especially in the Peer network consisting of Windows 9x/2000.

Enable NetBIOS on TCP/IP in "Advanced TCP/IP Settings \ WINS" to enhance LAN compatibility.

IPX

Full name: Internetwork
Packet Exchange (Packet Exchange between networks). IPX is the underlying network protocol that comes with Novell NetWare. It is mainly used to control the addressing and routing of packets within or between the LAN, it is only responsible for the transmission of data packets in the LAN, does not guarantee the integrity of the message, and does not provide error correction services.

When transmitting data packets in a LAN, if the receiving node is in the same network segment, the data is directly transmitted to the receiving node based on the node ID through the IPX protocol. If the receiving node is not in the same network segment, the IPX protocol can be used to send data packets to the NetWare server and continue transmission. During use, the network administrator can use the corresponding IPX routing command, such as "routing
Ipx add/set staticroute indicates adding or configuring static IPX routes in the IPX route table, and "routing ipx set global" indicates configuring global IPX route settings.

SPX

Sequences
The SPX Protocol is based on Xerox SPP (Sequences Packet Protocol) Protocol of Xerox, it is also a network protocol for LAN developed by Novell. In the LAN, the SPX protocol is mainly responsible for error-free processing of the entire transmitted data, that is, error correction.

The SPX protocol is generally used together with the IPX protocol described above in IPX/SPX protocol. It is mostly used in Netware network environments and online games.

NetBEUINetBEUI, that is, NetBios
Enhanced User Interface, or NetBios Enhanced User Interface. It is an enhanced version of NetBIOS and has been used by many operating systems, such as Windows for Workgroup and Win
9x series, Windows NT, etc. NETBEUI is a non-routing protocol developed for IBM for carrying NETBIOS communications. Before introducing NETBEUI, We need to briefly introduce NETBIOS:

NetBIOSNetBIOS (NetBIOS
Services Protocols (Basic Input/Output System Protocol) is a small LAN developed by IBM and mainly used for dozens of computers. The NetBIOS protocol is an application programming interface (API) that can be used by a program on the LAN. It provides a unified command set for the program to request low-level services, it serves to provide networks and other special functions for LAN. Almost all LAN networks work on the basis of the NetBIOS protocol. In Windows, NETBIOS is automatically installed after TCP/IP is installed by default. For example, in Windows
In 2000/XP, when "automatically obtain IP Address" is selected, the DHCP server is enabled and the NetBIOS settings are used for the server. If the static IP address is used or the DHCP server does not provide NetBIOS settings, enable NetBIOS on TCP/IP. The specific setting method is as follows: first open "Control Panel" and double-click "network connection" to open the local connection attribute. In the Properties window, select "Internet Protocol (TCP/IP)" on the "General" tab and click "properties. In the displayed window, click the "advanced" button. In the "Advanced TCP/IP Settings" window, select the "WINS" tab, the corresponding NetBIOS settings are available in the "NetBIOS Settings" area.

The difference between NETBIOS and NETBEUI: NetBIOS can establish up to 254 communication channels with other nodes. NetBEUI no longer has this restriction. It allows every process on the WindowsNT machine to communicate with up to 254 nodes. The NetBIOS name can contain a maximum of 15 characters. The call layer application uses it to communicate with a remote computer. NetBEUI implements message transmission in the logical channel through the SMB protocol (ServerMessageBlock-Server Message Block, which was originally applied to LANManager of 3COM. NetBEUI is always included in NetBIOS. NetBIOS can run on several different transmission protocols, including NetBEUI, TCP/IP, and IPX/SPX, the last three are located between the driver interface at the network layer and the driver interface at the transport layer. However, the NetBIOS service running on one Transport Protocol cannot communicate with the NetBIOS service running on another transport protocol. Four types of SMB that NetBIOS can use (grant local file redirection to Windows computers to access remote file systems ).

Netbios (basic network input/output system) was initially developed by IBM and Sytek as an API to enable user software to use LAN resources. Since its birth, Netbios has become the basis of many other network applications. Strictly speaking, Netbios
Is the interface standard for accessing network services.

Netbios was originally used as THE network controller
The ibm lan is designed as a software layer that connects to network operating systems through specific hardware. Netbios is extended and allows the program to use the Netbios interface to operate the IBM licensing ring structure. Netbios
Has been recognized as an industrial standard, usually referred to Netbios-compatible LANs.

It provides a set of methods for network programs to communicate with each other and transmit data. Basically, Netbios allows programs and network sessions. It aims to separate the program from any type of hardware property. It also frees software developers from the following responsibilities: network error fixing, low-layer information addressing, and routing. Using the Netbios interface, you can do a lot of work for software developers.

Netbios standardizes interfaces between program and LAN operation capabilities. They can refine the program to which layer of the OSI model is written so that the program can be transplanted to other networks. In the Netbios LAN environment, the computer name is known by the system. Each computer in the network has a permanent name compiled using different methods. These names will be further discussed below.

By using Netbios datagram or broadcast, a PC on the Netbios LAN establishes a session to communicate with each other. Sessions allow more information to be transmitted, detected, and corrected. Communication is based on one-to-one communication. The datagram or broadcast mode allows one computer to communicate with multiple other computers at the same time, but the information size is limited. No errors are detected or corrected using the datagram or broadcast method. However, you do not need to establish a session for datagram communication.

In this environment, all communication is submitted to NetBIOS in a format called "Network Control Block. The allocation of these blocks in the memory depends on the user program. These "network control blocks" are allocated to the domain and reserved for input and output respectively.

In today's environments, NetBIOS is a common protocol. Ethernet, licensing ring, and ibm pc network support NetBIOS. In its original version, it serves only as an interface for programs and network adapters. Since then, the transfer function has been added to NetBIOS, increasing its functionality.

In NetBIOS, connection-oriented (tcp) and non-connection (udp) communication are supported. It supports broadcast and replay, and supports three separate services: naming, session, and datagram.

NETBEUI

The NETBEUI protocol is useful in many cases. It is the default protocol of the operating system before Windows 98. In short, the NetBEUI protocol is a short and concise broadcast protocol with high communication efficiency. It does not need to be set after installation. It is especially suitable for transmitting data in "Network neighbors. In addition to the TCP/IP protocol, it is recommended that NetBEUI be installed on LAN computers.

NETBEUI lacks the routing and network-layer addressing functions, which is both its biggest advantage and its biggest disadvantage. Because it does not require additional network addresses and network-layer headers and tails, it is fast and effective and suitable for small workgroup environments that only individual networks or the entire environment are bridging.

Because routing is not supported, NETBEUI will never become the main protocol of the enterprise network. The only address in the NETBEUI frame is the data link layer Media Access Control (MAC) address, which identifies the network adapter but does not identify the network. The vro forwards the frame to the final destination based on the network address, but the NETBEUI frame does not have this information.

The bridge is responsible for forwarding and communication between networks according to the data link layer address, but there are many disadvantages. Because all broadcast communication must be forwarded to each network, the scalability of the bridge is poor. NETBEUI includes the recording of Broadcast Communication and relies on it to resolve naming conflicts. Generally, the number of NETBEUI bridging hosts is less than 100.

In recent years, networks dependent on second-layer switches have become more common. The entire conversion environment reduces the network utilization, even though the broadcast is still forwarded to each host in the network. In fact, the combined use of 350-BASE-T Ethernet allows the conversion of the NetBIOS network to expand to hosts, in order to prevent Broadcast Communication from becoming a serious problem.

The NetBEUI protocol is mainly used in a local LAN and generally cannot be used to communicate with computers in other networks. It is different from TCP/IP and IPX/SPX protocols. In Windows, the methods for installing the NetBEUI protocol are different. For example, in Windows
In 98/ME, double-click "network" in "Control Panel", "add" protocol in the Open Properties window, and select Microsoft's NetBEUI protocol for installation. In Windows XP, the "nbf. copy the sys file to the % SYSTEMROOT % \ SYSTEM32 \ DRIVERS \ directory, and then copy "netnbf. copy the inf file to the % SYSTEMROOT % \ INF \ directory. When "protocol" is installed, the "NetBEUI protocol" is displayed in the selection window.

We will introduce the TCP/IP protocol later.