Network protocol Application Detailed

I. Communication protocol
When building a network, you must choose a network communication protocol, so that users can "communicate" with each other. Protocol (PROTOCOL) is a set of rules that network devices use to communicate, and this set of rules can be understood as a common language that each can understand. The protocols on the network can be summed up in two categories: "Internal agreements" and "external agreements", which are described separately below.
1. Internal agreements
1978, the International Organization for Standardization (ISO) developed a standard model for network communications, called the OSI/RM (open system Interconnect/reference model, open Systems Interconnection reference models) architecture. The structure is divided into seven layers, which are physical layer, data link layer, network layer, transport layer, Session layer, presentation layer and application layer. There is a particular protocol form between the upper and lower layers of any network device, and there is also a protocol agreement between the two devices, such as workstations and servers, that are used in the same layer. Here, we define the agreement between the upper and lower layers and the same layer as the "internal protocol". Internal protocols are rarely involved in networking, and are mainly provided to network developers. If you're just trying to set up a network, don't bother with internal protocols.
2. External agreements
The external agreement is the protocol that we must choose when we set up the network. Because it is directly responsible for the mutual communication between computers, it is often called a network communication protocol. Since the advent of the Internet, many companies have been involved in the development of communications protocols such as IBM, Banyan, Novell, and Microsoft. Each company develops the agreement originally is in order to satisfy own network communication, but along with the network application popularization, the different network interconnection request is more and more urgent, therefore the communication protocol becomes the key technology which solves the network interconnection. Just as a common language is needed to communicate between people who use different native languages, communication between networks also requires a common language, which is the communication protocol. At present, the Common Communication Protocol (external protocol) in LAN is mainly NetBEUI, ipx/spx and its compatible protocol and TCP/IP.
3. Select the principle of network communication protocol
In choosing a communication protocol, we should generally follow the following principles:
First, the selected protocol should be consistent with the network structure and functionality. If your network has multiple network segments or to connect via routers, you cannot use NetBEUI protocols that do not have the ability to route and cross-segment operations, and you must select protocols such as ipx/spx or TCP/IP. In addition, if your network is small, and only for simple file and device sharing, then you are most concerned about network speed, so select the protocol should choose to occupy small memory and high bandwidth utilization protocols, such as NetBEUI. When your network is large and the network structure is complex, you should choose a protocol with better manageability and scalability, such as TCP/IP.
Second, in addition to special circumstances, a network as far as possible to select only one communication protocol. The practice of many people is to select multiple protocols at a time, or to select all the protocols provided by the system, in fact it is undesirable to do so. Because each protocol consumes the computer's memory, the more protocols you choose, the more memory resources are consumed by the computer. On the one hand, it affects the speed of computer operation, on the other hand, it is not conducive to network management. In fact, a common communication protocol in a network can meet the needs.
Third, pay attention to the protocol version. Each protocol has its own development and refinement process, so there are different versions, each version of the Protocol has its most appropriate network environment. Overall, the high version protocol features and performance is better than the lower version. Therefore, in the selection, in meeting the requirements of network functions, we should try to choose a high version of the communication protocol.
The consistency of the agreement. If you want to make a conversation between two computers that are interconnected, they must use the same communication protocol. Otherwise, the middle also needs a "translation" for different protocol conversion, so that not only affect the speed of communication, but also not conducive to the security and stability of the network operation.

Two, three kinds of communication protocols commonly used in LAN
1.NetBEUI protocol
The characteristics of NetBEUI communication protocol. NetBEUI (NetBIOS Extended user Interface), developed by IBM in 1985, is a small, efficient and fast communication protocol. NetBEUI is also Microsoft's favorite communication protocol, so it is known as the "mother tongue" of communication protocols in all Microsoft products. Microsoft mainly chooses NetBEUI as its communication protocol in its early products, such as DOS, LAN Manager, Windows 3.x, and Windows for workgroup. In today's mainstream Microsoft products, such as Windows 95/98 and Windows NT, NetBEUI has become its inherent default protocol. Some people position the Winnt as the low-end network server operating system, which has a direct relationship with Microsoft's products too dependent on NetBEUI. NetBEUI is specially for several to hundreds of PCs composed of a single network segment of the small LAN design, it does not have to work across the network segment function, that is, NetBEUI does not have the routing function. If you have more than one network card installed on a server, or if you want to use a router and other devices to interconnect two LAN, you will not be able to use the NetBEUI communication protocol. Otherwise, there will be no communication between the devices connected to different network adapters (one network segment for each NIC), and between different LANs.
Although NetBEUI has many unsatisfactory places, it also has advantages that other agreements do not have. In three communication protocols, NetBEUI consumes the least amount of memory and does not require any configuration in the network. Especially in today's Microsoft products almost exclusive PC operating system, it is very suitable for the vast number of web beginners to use.
The relationship between NetBEUI and NetBIOS. Attentive readers may have found that the NetBEUI contains a standard NetBIOS for network interfaces. NetBIOS (network basic input/output system, network basic input/output systems) is a set of standards developed by IBM in 1983 to achieve communication between PCs, with the aim of developing a communication specification that is used only on small LANs. The network is composed of PC, the maximum number of users not more than 30, its characteristic is to highlight a "small" word. Later, IBM discovered many of the drawbacks of NetBIOS, so it was improved in 1985 and launched the NetBEUI communication protocol. Immediately, Microsoft will NetBEUI as its client/server network system Basic communication protocol, and further expanded and improved. The most representative part of the NetBEUI is the addition of a component called SMB (Server message Blocks) to reduce network traffic congestion. For this reason, the NetBEUI protocol is sometimes referred to as the SMB protocol.
People often confuse NetBIOS and NetBEUI, in fact, NetBIOS is only a network application interface specification, is the foundation of NetBEUI, it does not have strict communication protocol function. The NetBEUI is a network transport protocol based on NetBIOS.
2.ipx/spx and its compatibility agreement
The characteristics of ipx/spx communication protocol. Ipx/spx (internetwork Packet exchange/sequences Packet Exchange, Internet packet switching/sequential packet switching) is Novell's communication protocol set. The obvious difference with NetBEUI is that the ipx/spx appears to be quite large and has strong adaptability in complex environment. Because, ipx/spx at the beginning of the design to consider the problem of multiple network segment, with a powerful routing function, suitable for large-scale network use. Ipx/spx and its compatible protocols are the best option when the client is connected to a NetWare server. In the non-Novell network environment, however, ipx/spx is not generally used. In particular, the Ipx/spx communication protocol cannot be used directly in Windows NT networks and Peer-to-peer networks made up of Windows 95/98.
How the Ipx/spx protocol works. Ipx/spx and its compatible protocols do not require any configuration, it can identify itself by "network address." The network address in the Novell network consists of two parts: a "network ID" indicating the physical network segment and a "Node ID" indicating the special device. Where the network ID is centralized in a NetWare server or router, the node ID is the ID number (NIC card number) of each network card. All network IDs and node IDs are unique "internal IPX addresses." It is because of the uniqueness of the network address that the ipx/spx has a strong routing function.
In the Ipx/spx protocol, IPX is the lowest level of NetWare protocol, it is only responsible for the movement of data in the network, does not guarantee the success of data transmission, and does not provide error correction services. When IPX is responsible for data transfer, if the receiving node is within the same network segment, the data is passed directly to the node's ID, and if the receiving node is remote (not within the same network segment or on a different LAN), the data is handed to the network ID in the NetWare server or router to continue the next transfer of the data. SPX is responsible for error-free processing of the data being transmitted throughout the Protocol, so we will also call ipx/spx "Novell's protocol set."
NWLink communication Protocol. There are two ipx/spx compatible protocols in Windows NT: "NWLink spx/spx Compatibility Protocol" and "NWLink NetBIOS", which are collectively referred to as "NWLink communication Protocol". The NWLink protocol is the implementation of Novell Ipx/spx protocol in Microsoft Network, which inherits the advantages of Ipx/spx protocol and adapts to Microsoft's operating system and network environment. Windows NT network and Windows 95/98 users can use the NWLink protocol to obtain services for NetWare servers. NWLink communication protocol is the best option if your network is moving from Novell to Microsoft, or when two platforms coexist. However, when using the NWLink protocol, where the "NWLink ipx/spx Compatibility Protocol" resembles the "Ipx/spx Compatibility Protocol" in Windows 95/98, it can only be used as a client-side protocol to access NetWare servers, leaving the NetWare server. This compatibility protocol will not work, and the NWLink NetBIOS protocol not only delivers information between NetWare servers and Windows NT, but can also be used for any communication between Windows NT and Windows 95/98.
3.TCP/IP protocol
TCP/IP (Transmission Control protocol/internet Protocol, Transmission Control Protocol/Internet Protocol) is the most commonly used communication protocol, which is a universal protocol in the computer world. In a local area network, TCP/IP first appeared on UNIX systems, and now almost all vendors and operating systems are starting to support it. At the same time, TCP/IP is the basic protocol for the Internet.
The characteristics of TCP/IP communication protocols. TCP/IP has high flexibility to support any size network and can connect almost all servers and workstations. However, its flexibility also brings a lot of inconvenience to its use, when using NetBEUI and Ipx/spx and its compatible protocols, no configuration is required, and the TCP/IP protocol is used with complex settings first. Each node requires at least one IP address, one subnet mask, one default gateway, and one host name. Such a complex setting is indeed inconvenient for some users who first know the web. However, a tool called Dynamic Host Configuration Protocol (DHCP) is available in Windows NT, which automatically reduces the burden on the networking effort and avoids errors by automating the information that the client needs to be connected to the network. Of course, the functionality that DHCP has has to be implemented by a DHCP server.
As with Ipx/spx and its compatible protocols, TCP/IP is also a routable protocol. However, there are some differences between the two. TCP/IP addresses are hierarchical, which makes it easy to identify and locate users on the Web, while also increasing the utilization of network bandwidth. A server running the TCP/IP protocol, such as a Windows NT Server, can also be configured as a TCP/IP router when required. Unlike TCP/IP, IPX in the Ipx/spx protocol uses a broadcast protocol that frequently has broadcast packet congestion and therefore does not get the best network bandwidth.
The TCP/IP protocol in Windows 95/98. Users of Windows 95/98 can not only use TCP/IP to build Peer-to-peer networks, but also easily access other servers. It is noteworthy that if the Windows 95/98 Workstation has only the TCP/IP protocol installed, it cannot join the Windows NT domain directly. Although the workstation can access the Internet by running a proxy server on a Windows NT Server (such as proxy server), it cannot log on to the domain of the Windows NT Server through it. You must also install the NetBEUI protocol on Windows 95/98 if you want to have Windows 95/98 users who are only installing the TCP/IP protocol to join the Windows NT domain.
TCP/IP protocol configuration in the LAN. When it comes to TCP/IP protocol, many users are bothered by their complex description and configuration, and they are not at ease to use them. In fact, as far as the LAN users, as long as you have mastered some knowledge of TCP/IP, it is also very convenient to use.
Basic knowledge of IP addresses. As noted earlier in the Ipx/spx protocol, the address of IPX consists of a "network ID" (network ID) and a node ID, the Ipx/spx protocol is identified by an IPX address for an online user. Similarly, the TCP/IP protocol also relies on its own IP address to identify the location and identity of the Internet, the IP address also by the "Network ID" and "Node ID" (or host ID, address) two components. A complete IP address is made up of 32 bit binary digits, each 8 bits (1 bytes) is a segment (Segment), a total of 4 segments (SEGMENT1~SEGMENT4), and segments with "." Number separated. In order to facilitate the application, the IP address in the actual use is not directly binary, but with the well-known decimal number, such as 192.168.0.1. The full composition of the IP address: Network ID and Node ID are included in the 32-bit binary number.

III. installation, setup and testing of communication protocols
Some protocols in the LAN that are installed automatically when the operating system is installed. If you install Windows NT or Windows 95/98, the NetBEUI communication protocol is automatically installed. When you install NetWare, the Ipx/spx communication protocol is automatically installed. Of these three protocols, NetBEUI and ipx/spx can be used directly after installation, but TCP/IP is required to be set up. Therefore, the following is mainly based on the TCP/IP protocol in Windows NT environment, introduces its installation, setup and testing methods, other operating systems in the protocol related to the operation of the same as Windows NT, or even simpler.
Installation of TCP/IP communication protocols. In Windows NT, if you do not have a TCP/IP communication protocol installed, select Start/Settings/Control Panel/Network, the Network dialog box appears, select Protocol/Add in the dialog box, select the TCP/IP protocol, and then click OK. The system will ask you if you want to set up a DHCP server. If your IP address is fixed (usually this is the case), choose "No". The system then starts copying the required files from the installation disk.
The settings of the TCP/IP communication protocol. In the Network dialog box, select the installed TCP/IP protocol, open its properties, and enter the assigned IP address and subnet mask at the specified location. If the user also accesses resources for other widnows NT networks, you can also enter the address of the gateway at the default gateway.
Testing of TCP/IP communication protocols. After the TCP/IP protocol is installed and set up, test must be performed before use in order to ensure that it works properly. I suggest that you use the system's own tool program: PING.EXE, the tool can check whether any one user with the same network segment of other users connected to the other network segments of the normal users, but also to check out their own IP address and other users of the IP address conflict. If the IP address of the server is 192.168.0.1, if you want to test whether your machine is connected to the server, simply switch to the DOS prompt and type the command "PING 192.168.0.1". If a response similar to "Reply from 192.168.0.1 ..." appears, the TCP/IP protocol works properly, and if you display information similar to "Request timed out", the TCP/IP protocol settings for both parties may be incorrect. or other connections to the network (such as network cards, hub or cable, etc.) have problems, you need to further check.

Iv. Summary
If you are building a small, single network segment of the network, and the need for external connectivity, it is best to choose the NetBEUI communication protocol. If you are migrating from NetWare to Windows NT, or if both platforms coexist, ipx/spx and its compatible protocols provide a good transport environment. If you are planning an efficient, interconnected, and scalable network, TCP/IP will be the ideal choice