Configure the communication protocol in the LAN

Whether it is a Windows 95/98 peer network composed of several machines, or a large windows NT, Novell, or UNIX/xenix lan, anyone who has personally established or managed the network, you have encountered problems in selecting and configuring network communication protocols. Many users are not very clear about the protocols in the network and their features. Therefore, communication protocols that do not conform to their network characteristics are often used in the network. As a result, the network is not connected, or the speed is too slow and the work is unstable, which affects the network reliability. In fact, different network protocols have their own needs. Each protocol has its own operating system and working environment. The communication protocol that runs well on one network may not work well on another seemingly similar network. Therefore, the choice of communication protocols is particularly important when you build a network. Based on the LAN environment, this article focuses on Windows NT, taking into account Netware, Windows 95/98 and other operating systems, and introduces and analyzes the characteristics, performance, and necessary configuration methods of common communication protocols, for group network users and network management personnel.

A. Communication Protocol 

When creating a network, You must select a network communication protocol to allow users to "communicate" with each other ". Protocols are a set of rules for communication between network devices. These rules can be understood as a common language that can be understood by each other. There are two types of protocols in the Network: internal protocols and external protocols, but it can solve some confusion in concepts and applications.

1. Internal protocols

In 1978, the International Organization for Standardization (ISO) developed a standard model for network communication, known as the OSI/RM (Open System Interconnect/reference model, Open System Interconnection Reference Model) architecture. The structure consists of seven layers: physical layer, data link layer, network layer, transmission layer, Session Layer, presentation layer, and application layer. The upper and lower layers of any network device have their specific protocol forms, and the same layer of the two devices (such as workstations and servers) also have their own protocol conventions. Here, we define all the protocols between the upper and lower layers and between the same layer as "internal protocols ". Internal protocols are rarely involved in networking. They are mainly used by network developers. If you only want to build a network, ignore the internal protocol.

2. External protocols

External protocols are the protocols we must select when networking. Because it is directly responsible for mutual communication between computers, it is usually called a network communication protocol. Since the advent of the network, many companies have invested in the development of communication protocols, such as IBM, Banyan, Novell, and Microsoft. Protocols developed by each company are initially designed to meet their own network communication requirements. However, with the popularization of network applications, interconnection between different networks is becoming more and more urgent, therefore, communication protocols have become a key technology to solve the interconnection between networks. Just like communication between people using different native languages requires a common language, communication between networks also requires a common language, which is a communication protocol. Currently, common communication protocols (external protocols) in Lan are netbeui, IPX/SPX, and their compatible protocols and TCP/IP.

3. Principles of network communication protocol selection

We should follow the following principles when selecting communication protocols:

1. The selected protocol must be consistent with the network structure and functions. If your network has multiple CIDR blocks or you want to connect to a vro, you cannot use the netbeui protocol that does not support routing and cross-network segment operations, you must select IPX, SPX, TCP/IP, and other protocols. In addition, if your network size is small and you only want to share simple files and devices, you are most concerned about the network speed, therefore, when selecting a protocol, you should select a protocol with a low memory usage and high bandwidth utilization, 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.

2. In special cases, select only one communication protocol for a network. In reality, many people choose multiple protocols at a time or all the protocols provided by the system. In fact, this is not desirable. Because each protocol occupies the computer's memory, the more protocols selected, the more memory resources occupied by the computer. On the one hand, it affects the speed of computer operation, and 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 development and improvement process, so different versions have emerged. Each version of the protocol has its most suitable network environment. Overall, the features and performance of the higher version protocol are better than those of the lower version. Therefore, when selecting a communication protocol that meets the network functional requirements, we should try to select a higher version of the communication protocol.

4. protocol consistency. The communication protocols used by the two computers for interconnection must be the same. Otherwise, a "Translation" is required to convert different protocols, which not only affects the communication speed, but also is not conducive to the security and stable operation of the network.

B. Three common communication protocols in LAN 

1. netbeui Protocol
Features of netbeui communication protocol. Netbeui (NetBIOS extended User Interface) was developed by IBM in 1985. It is a small, efficient, and fast communication protocol. Netbeui is also Microsoft's favorite communication protocol, so it is called the "mother tongue" of communication protocols in all Microsoft products ". Microsoft chose 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. Someone has positioned winnt as the operating system of the low-end network server, which is directly related to Microsoft's product dependency on netbeui. Netbeui is designed for a small local area network composed of several to more than PCs. It does not have the function of cross-network segment work, that is, netbeui does not have the routing function. If you have installed Multiple NICs on a server or want to connect two LAN devices, such as routers, you cannot use the netbeui communication protocol. Otherwise, communication between devices connected to different NICs (each network card is connected to a network segment) and between different local networks cannot be performed.

Although netbeui has many unsatisfactory features, it also has advantages that are not available in other protocols. Among the three communication protocols, netbeui occupies the least memory and does not require any configuration in the network. Especially today, Microsoft products have almost exclusive PC operating systems. It is suitable for beginners of the majority of networks.

The relationship between netbeui and NetBIOS. Careful readers may have discovered that netbeui contains a network interface standard NetBIOS. NetBIOS (Network Basic Input/Output System) is a set of standards developed by IBM in 1983 to implement inter-PC communication, the purpose is to develop a communication specification that is only used on a small LAN. The network is composed of PCs with a maximum of 30 users. It highlights the word "small. Later, IBM found many defects in NETBIOS, so it was improved in 1985 and released the netbeui communication protocol. Then, Microsoft used netbeui as the basic communication protocol for its client/server network system, and further expanded and improved it. The most representative is the addition of an SMB (Server Message blocks, Server Message Block) component in netbeui to reduce network congestion. Therefore, the netbeui protocol is sometimes referred to as the "SMB protocol ".

NetBIOS and netbeui are often confused. In fact, NetBIOS can only be regarded as the interface specification of a network application, and is the basis of netbeui. It does not have strict communication protocol functions. Netbeui is a network transmission protocol based on NetBIOS.

2. IPX/spx and its compatible protocols
Features of IPX/SPX communication protocols. IPX/SPX (Internetwork Packet Exchange/sequences Packet Exchange, Internet Packet Exchange/ordered Packet Exchange) is the communication protocol set of Novell. The obvious difference from netbeui is that IPX/SPX is relatively large and has strong adaptability in complex environments. Because IPX/SPX takes into account the problem of multiple CIDR blocks at the beginning of the design, 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/SPX communication protocols cannot be directly used in Windows NT networks and Windows 95/98 peer networks.

IPX/SPX protocol. IPX/spx and its compatible protocols do not require any configuration. It can identify itself through the "Network Address. The network address in the Novell Network is composed of two parts: the "Network ID" indicating the physical network segment and the "Node ID" indicating the special device ". The network ID is concentrated in the NetWare server or vro, And the node ID is the ID of each NIC (NIC card number ). All network IDs and node IDs are unique "Internal IPX addresses ". It is precisely because of the uniqueness of the network address that IPX/SPX has a strong routing function.

In IPX/SPX protocols, IPX is the bottom-layer protocol of Netware. It is only responsible for moving data in the network, and does not guarantee whether the data is transmitted successfully or provide error correction services. When IPX is responsible for data transmission, if the receiving node is in the same network segment, it directly transmits the data according to the node ID. If the receiving node is remote (not in the same network segment, or in different LAN), the data will be handed over to the NetWare server or the network ID in the router, continue the next data transmission. SPX is responsible for error-free processing of transmitted data throughout the Protocol. Therefore, we call IPX/SPX a "Novell protocol set ".

Nwlink communication protocol. Windows NT provides two IPX/SPX compatible protocols: "nwlink SPX/SPX compatible protocol" and "nwlink NetBIOS", collectively referred to as "nwlink communication protocol ". The nwlink protocol is the implementation of Novell's IPX/SPX protocol in Microsoft's network. It inherits the advantages of IPX/SPX protocol while adapting to Microsoft's operating system and network environment. Users of Windows NT and Windows 95/98 can use the nwlink protocol to obtain the services of the NetWare server. If your network is switched from the Novell environment to the Microsoft platform, or the two platforms coexist, the nwlink communication protocol is the best choice. However, when using the nwlink protocol, the "nwlink IPX/SPX compatibility protocol" is similar to the "IPX/SPX compatibility protocol" in Windows 95/98 ", it can only access the NetWare server as a client protocol, leaving the NetWare server, this compatibility protocol will be ineffective; the "nwlink NetBIOS" protocol not only transfers information between the NetWare server and Windows NT, but also can be used for communication between Windows NT and Windows 95/98.

3. TCP/IP protocol

Transmission Control Protocol/Internet Protocol (Transport Control Protocol/Internet Protocol) is currently the most common communication protocol, which is a common protocol in the computer world. In the LAN, TCP/IP first appeared in Unix systems, and is now supported by almost all vendors and operating systems. At the same time, TCP/IP is also the basic protocol of the Internet.

The characteristics of TCP/IP communication protocol. With high flexibility, TCP/IP supports networks of any size and connects almost all servers and workstation. However, its flexibility also makes it inconvenient to use. You do not need to configure netbeui and IPX/SPX and Their compatible protocols, the TCP/IP protocol must be configured in a complex way. Each node requires at least one "ip address", one "subnet mask", one "Default Gateway", and one "host name ". Such complicated settings are inconvenient for some users who are familiar with the network. However, a tool called Dynamic Host Configuration Protocol (DHCP) is provided in Windows NT, which can automatically allocate the client with the information required to connect to the network, reduces the burden on the Internet and avoids errors. Of course, the functions of DHCP must be implemented by a DHCP server.

Like IPX/spx and its compatible protocols, TCP/IP is also a routable protocol. However, there are some differences between the two. The TCP/IP address is hierarchical, which makes it easy to identify and find online users, and also improves the network bandwidth utilization. When necessary, a server running the TCP/IP protocol (such as a Windows NT Server) can also be configured as a TCP/IP router. Unlike TCP/IP, IPX in IPX/SPX uses a broadcast protocol, which often blocks broadcast packets, so it cannot obtain the optimal network bandwidth.

The TCP/IP protocol in Windows 95/98. Windows 95/98 users can not only use TCP/IP to build an equivalent network, but also access other servers conveniently. It is worth noting that if the Windows 95/98 workstation only installs the TCP/IP protocol, it cannot be directly added to the Windows NT domain. Although the workstation can access the Internet through a proxy server running on a Windows NT Server (such as a proxy server), it cannot log on to the domain of the Windows NT Server. If you want to add a Windows 95/98 user that only installs the TCP/IP protocol to the Windows NT domain, you must also install the netbeui protocol on Windows 95/98.

TCP/IP Protocol configuration in LAN. When talking about the TCP/IP protocol, many users are troubled by its complicated descriptions and configurations. In fact, for LAN users, as long as you have some knowledge about TCP/IP, it is also very convenient to use.

Basic knowledge about IP addresses. As mentioned earlier, the IPX/SPX protocol is known. The IP address of IPX consists of the "Network ID" and "Node ID, the IPX/SPX protocol uses IPX addresses to identify online users. Similarly, the TCP/IP protocol uses its own IP address to identify the location and identity on the Internet. The IP address is also identified by the "Network ID" and "Node ID" (or host ID, host address. A complete IP address is composed of 32-bit binary numbers. Each 8-bit (1 byte) is a segment (segment). A total of 4 segments (segment1 ~ Segment4), segments and segments are separated. For ease of application, IP addresses are not directly expressed in binary format, but in decimal format, such as 192.168.0.1. The complete composition of IP addresses: "network ID" and "Node ID" are included in 32-bit binary numbers. At present, IP addresses are mainly divided into three categories: A, B, and C (In addition, there are also D and E addresses. Currently, these two types of IP addresses are basically not used in LAN, so this article does not cover it). Class A is used for large-scale networks, Class B is used for medium-sized networks, and class C is generally used for small networks such as local area networks. Specifically, segment1, the first segment in the Class A address, is used to represent the "Network ID", and the first digit in the 8-bit binary number of segment1 must be "0 ". The other three segments represent "Node IDs". In Class B addresses, the first two segments represent "network IDS", and the first two of the eight-bit binary numbers of segment1 must be "10 ". The last two segments are used to represent "Node IDs". In Class C addresses, the first three segments represent "network IDS", and the first three of the eight-bit binary numbers of segment1 must be "110 ". The last segment of segment4 is used to represent the "Node ID ".

It is worth mentioning that all "network IDS" in the IP address must apply to an InterNIC (Internet Network Information Center, the "Node ID" can be freely allocated. Currently, only class c ip addresses are available, and Class A and Class B resources are exhausted. However, when selecting an IP address, the general principle is: the IP address of each device in the network must be unique, and the same IP address cannot appear on different devices. Lists the related attributes of the "Network ID" in the IP address. The "Node ID" is freely allocated by the user if it is not repeated. In fact, IP addresses are classified to Ensure network interconnection. If your network is a closed network, any of the three types of addresses can be used directly (just in case, you can still use Class c ip addresses honestly ).

Subnet Mask. The IP address is interpreted as a subnet mask. From the name, we can see that the subnet mask is used for subnet management. It is mainly used to expand the "Network ID" of the IP address in the Multi-network segment environment. For example, if the IP address of a node is 192.168.0.1, It is a class C network. In the first three paragraphs, a total of 24 bits are used to represent the "Network ID", which is a very precious resource. In the last section, a total of 8 bits can be freely allocated as "Node ID. However, if the company's LAN is segmented, or the network is interconnected by multiple LAN, do you want to apply for a "network ID" for each network segment or each lan? This is obviously unreasonable. In this case, we can use the subnet mask function to use the IP addresses of one or more nodes as "network IDS" to extend the limitations of the "Network IDS.

When we set the IP address of a node such as 192.168.0.1 to a "network ID", how do other devices on the network know that it is a "network ID ", instead of a node IP address? The subnet mask should be used to inform you. Subnet Mask: If the binary number of a bit is "1", it knows that it is part of the "Network ID; if it is "0", it is considered as part of the "Node ID. For example, when 192.168.0.1 is used as a "network ID", its subnet mask is 11111111.111111.111111.00000001. The corresponding decimal number is 255.255.255.1. Otherwise, its subnet mask is 11111111.11111111.111111.00000000, and the corresponding decimal number should be 255.255.255.0. With the subnet mask, you can easily perform cross-network operations. However, to enable the subnet mask to work properly, all devices in the same subnet must support the subnet mask and the subnet mask is the same. Lists the default subnet masks of Networks A, B, and C.

Gateway. A gateway is used to connect to a heterogeneous network. It acts as a translation and is responsible for translating different communication protocols so that the two networks running different protocols can communicate with each other. If a Windows NT user running the TCP/IP protocol wants to access the Novell Network Resources running the IPX/SPX protocol, the gateway must act as the intermediary. If two networks running the TCP/IP protocol are interconnected, you can use the default gateway provided by Windows NT. How should I allocate the gateway address? For example, if a user of Network A wants to access resources of Network B, a gateway must be set in Network, the gateway address should be the "Network ID" of B network (generally, it can be understood as the IP address of B network server ). What Should users of Network A access resources of Network C at the same time? You only need to add the "Network ID" of Network C to the gateway of Network. And so on ...... The number of IP addresses that the gateway can connect.

Host Name. Only the IP address that represents the user or device identity in the network. But in general, a large number of IP addresses are not easy to remember, and operations are not convenient. To improve this situation, we can give each user or device a meaningful name, such as "wangqun ". How do I know the corresponding IP address when "wangqun" is used in the network? This is completely done by the operating system, so we don't have to consider it.

C. Installation, setup, and testing of communication protocols 

Some protocols in the LAN are automatically installed when the operating system is installed. If you install Windows NT or Windows 95/98, the system automatically installs the netbeui communication protocol. When NetWare is installed, the system automatically installs the IPX/SPX communication protocol. Among the three protocols, netbeui and IPX/SPX can be directly used without any configuration after installation, but TCP/IP must be set as necessary. Therefore, the following describes how to install, set up, and test the TCP/IP protocol in a Windows NT environment. The related operations in other operating systems are basically the same as those in Windows NT, it is even simpler.

Install the TCP/IP communication protocol. In Windows NT, if the TCP/IP communication protocol is not installed, you can select "Start/set/control panel/network". The "network" dialog box appears, select "protocol/Add" in the dialog box, select the TCP/IP protocol, and click "OK. The system will ask if you want to set "DHCP server? If your IP address is fixed (this is generally the case), select "no ". Then, the system starts to copy the required files from the installation disk.

TCP/IP communication protocol settings. In the "network" dialog box, select the installed TCP/IP protocol to open its "properties ". Enter the allocated "ip address" and "subnet mask" at the specified position ". If you want to access other Widnows NT network resources, you can also enter the gateway address in "Default Gateway.

Test the TCP/IP communication protocol. After the TCP/IP protocol is installed and configured, you must test it before use to ensure it works properly. I suggest you use the built-in tool program: Ping. EXE, the tool can check whether any user is connected to other users in the same network segment, whether the connection is normal with users in other network segments, you can also check whether your IP address conflicts with the IP addresses of other users. If the IP address of the server is 192.168.0.1, to test whether your machine is connected to the server, you only need to switch to the DOS prompt and type the command "Ping 192.168.0.1. If a message similar to "reply from 192.168.0.1…" appears ......" The response indicates that the TCP/IP protocol works normally. If the message similar to "request timed out" is displayed, it indicates that the TCP/IP protocol settings of both parties may be wrong, or other network connections (such as NICs, hubs, or connections), you need to further check.

D. Summary 

When establishing a LAN, the network communication protocol depends on the network size, network compatibility, and network management. If you are creating a small single network segment and there is no external connection, you 'd better select the netbeui communication protocol. If you are migrating from Netware to Windows NT, or if the two platforms coexist, IPX/spx and its compatible protocols provide a good transmission environment. If you are planning an efficient, interconnected, and scalable network, TCP/IP will be the ideal choice.