Network Management Development History-IP Address allocation planning article 2

4. Proxy server allocation
　　
Although the NAT address translation method is good, it also has its own shortcomings. Simply put, you can only perform IP address translation simply, but cannot implement file caching. This reduces Internet access traffic and prevents fast Internet access.
　　
The proxy server works differently from the NAT server. Instead of simply performing address translation, it acts as a proxy for computers in the network to access the Internet, return the access result to the user who initiated the request, and save the access result in the cache. When a network user sends a next Internet request, the server first checks whether the page content is saved in the cache. If yes, the server immediately calls out the page from the cache and returns it to the requester; if no, the system sends a request to the Internet and saves the access result again for access by other users.
　　
In addition, the proxy server also has some network firewall functions: it can hide computers in the network to improve network security, and restrict the access of some computers to the Internet; you can restrict Internet traffic when the bandwidth is narrow. You can disable access to some websites.
　　
In this case, proxy servers are more suitable for Internet shared access over large and medium-sized networks than NAT alone. However, the disadvantage of using a proxy server is that an additional server is required. In addition, the proxy server settings are complicated. However, considering the specific internal application of the organization, using the proxy server is the most appropriate.
　　
Ii. Dedicated (private) IP Address Allocation Method
　　
The scheme for allocating IP addresses that can be globally routed is fixed. It not only solves the problem of insufficient IP addresses, but also improves Internet access speed. Next, we should handle the allocation of dedicated IP addresses.
　　
First, consider the specific IP address. Small enterprises can select the "192.168.0.0" address segment, while large and medium-sized enterprises can select the "172.16.0.0" or "10.0.0.0" address segment.
　　
If we decide the IP address based on the number of computers in the network, this solution will certainly not work. This will be subject to future network conditions. If enterprises decide to purchase a batch of computers soon, the entire network may be re-designed because the selected IP address is not suitable.
　　
In fact, the division of networks is not very complex. You only need to consider the network situation in the foreseeable future, and pay attention to its universality and stability.
　　
Second, the IP Address Allocation Method. If the enterprise's Server operating system uses Windows NT/2000/2003 Server, the client uses Windows 98/me/2000/XP; windows provides three IP Address Configuration Methods for TCP/IP clients to meet different network requirements of Windows users. The specific IP Address Allocation method can be determined by the network administrator based on the network size and network applications.
　　
1. Manual allocation
　　
Manual IP address setting is also a frequently used allocation method. When manually setting, you need to set four IP addresses (IP address, subnet mask, default gateway, and DNS server address) for each computer on the network ). Therefore, it is usually used to set up small networks with fewer network servers and computers (for example, several to dozens of small networks ), or, it is used to allocate a small number of public IP addresses.
　　
The manually configured IP address is a static IP address. The computer will always have this IP address before reconfiguration. Therefore, you can access a computer on the network or determine whether the computer is on and connected to the network. However, the default gateway and DNS address must be the IP address in the CIDR Block of the computer, rather than the IP address in other CIDR blocks.
　　
In Windows 98/me/2000/XP, manually set the IP address of a computer. The specific configuration method is as follows. After the NIC driver is installed, restart the computer to enter the system, right-click the "Network Neighbor" icon on the desktop, and select Properties, at this time, you can find that the TCP/IP protocol has been automatically installed in it. Select and click the "properties" button under it. The TCP/IP attribute dialog box is displayed, on the "ip address" tab, change "automatically obtain IP Address" to "specify IP Address". In this case, you can specify the IP address and subnet mask that cannot be filled in gray.
　　
2. DHCP allocation
　　
To make TCP/IP protocols easier to manage, Microsoft and several vendors have jointly established an Internet standard-Dynamic Host configuration Protocol (DHCP ), it provides automatic TCP/IP configuration. The DHCP server provides clients with various configurations, such as IP addresses, subnet masks, and default gateway addresses.
　　
Computers in the network can automatically obtain IP address information through the DHCP server. The DHCP server maintains an address pool containing many IP addresses and rents out the pool based on computer requests. DHCP is the default Address Allocation Method in Windows.
　　
By default, all Windows 98/me/2000/XP systems use DHCP to allocate IP addresses. Therefore, if DHCP is still selected to allocate and manage IP addresses, network management will be much easier, in addition, you can easily configure the client. All we need to do is maintain a DHCP server.
　　
3. Automatic private IP addressing
　　
APIPA (Automatic Private IP Addressing) can automatically configure the TCP/IP protocol for a single network segment without a DHCP server. By default, a computer running Windows 98/Me/2000/XP first tries to contact the DHCP server in the network to obtain its IP address and other information from the DHCP server, and configure the TCP/IP protocol. If a connection to the DHCP server cannot be established, the computer uses the APIPA automatic addressing mode and automatically configures the TCP/IP protocol.
　　
When APIPA is used, Windows automatically obtains an IP address within the range of 169.254.0.1 -- 169.254.255.254. The subnet mask is 255.255.0.0, and the network connection is configured until the DHCP server is found.
　　
Because the IP address specified in the range of APIPA is retained by the network ID Organization (IANA), any IP address in this range is not used in the Internet. Therefore, APIPA is only used for a single network segment that is not connected to the Internet, such as small companies, homes, and offices.
　　
It is worth noting that the IP address allocated by APIPA only applies to the network of one subnet. If the network needs to communicate with other private networks or needs to access the Internet, APIPA cannot be used.