What is Load Balancing ?
What is Load Balancing ?
Internet-scale will be doubled every 100 days, customers want to get 7 days 24 hours non-stop availability and faster system response time, rather than a site repeatedly to see “Server Too Busy” and frequent system failure.
The core of the network in various parts, with the increased traffic, access traffic and rapid growth in data traffic, its processing capacity and computational intensity will also increase accordingly, allowing a single device simply can not afford. In this case, if the existing equipment to do throw a lot of hardware upgrades, which would result in a waste of available resources, and if have to face the next business volume increase, which in turn lead once again the high cost of hardware upgrades inputs, and even superior performance of the device and then can not meet current traffic needs. As a result, load-balancing mechanism came into being.
Load balancing (Load Balance) built on top of existing network infrastructure, which provides a cheap and effective and transparent method of expansion of network equipment and servers, bandwidth, increase throughput, enhance network data processing capability, increase network flexibility and availability of.
Load balancing has two meanings: First, a large number of concurrent access or data traffic to multiple nodes to share equipment dealt with separately, thus reducing waiting time for response; second, a single heavy-duty computing device sharing to more than one node do in parallel processing, each node device processing after the summary of the results returned to the user, the system processing capacity to be increased significantly
Load-balancing ==>> Load Balance
Due to current network, the various core business volume with the increased traffic and the rapid growth in data traffic, its processing capacity and computational intensity increases accordingly, allowing a single server device simply can not afford. In this case, if the existing equipment to do throw a lot of hardware upgrades, which would result in a waste of available resources, and if again faced with the next increase business volume, this in turn led to the high hardware upgrade once again the cost of inputs, or even superior performance, and then the equipment can not meet the current business volume growth in demand
For this case grew out of a cheap and effective and transparent approach to expanding the existing network equipment and server bandwidth, increase throughput, enhance network data processing capability, increase network flexibility and availability of technology is load balancing (Load Balance ).
Application of load-balancing technology mainly are as below.
1) DNS load balancing load balancing technology is the first achieved through the DNS in the DNS configuration for multiple addresses with a name, so check the name of the client machines will have one of the addresses, allowing access to different customers of different servers to achieve load balancing purposes. DNS load balancing is a simple and effective method, but it can not distinguish between different server, it does not reflect the server’s current state of operation
2) The Proxy Server load balancing using a proxy server, you can forward the request to internal servers, the use of such acceleration model is clearly static web pages can enhance the speed of access. However, you can also consider such a technique, using a proxy server forwards the request to multiple servers evenly, so as to achieve load balancing purposes
3) Address Translation Gateway load balancing to support address translation gateway load balancing can be an external IP address mapping for multiple internal IP addresses, for each TCP connection requests dynamically using one of the internal address to achieve load balancing purposes
4) The agreement internal support load-balancing In addition to these three kinds of load balancing methods in addition, some protocols related to internal support and load balancing features, such as HTTP protocol redirection capabilities, HTTP running on TCP connections at the highest level
5) NAT load balancing NAT (Network Address Translation Network Address Translation) is to simply convert an IP address to another IP address, are generally used for internal address are not registered and legitimate, have been registered Internet IP addresses between conversion. Internet IP Applicable to solving the Internet IP address of the tense, do not want to know the internal network structure of network externalities such occasions
6) Reverse proxy load balancing approach is general agent proxy on the internal network users to access internet connection to the server request, the client must specify the proxy server, and would have to be sent directly to the internet connection on the server, the request sent to the proxy server processing. Reverse Proxy Internet internet Reverse Proxy (Reverse Proxy) mode refers to the proxy server to accept connection requests on the internet, and then forwards the request to the server on the internal network, and the results obtained from the server back to the internet connection on the request of the client, At this point on the performance of the external proxy server as a server. Internet Reverse proxy load-balancing technology is to be connection requests from the internet on the way to reverse proxy to dynamically transmitted to the internal network on a multi-processing servers, so as to achieve load balancing purposes
7) Hybrid load balancing, in some large-scale networks, due to various hardware devices within the server cluster, each the size of the services provided by such differences, we can consider for each server cluster load balancing using the most appropriate way, and then again This is once again among multiple server farm load balancing or clustered together to provide services to the outside world as a whole (ie, this group of multiple servers as a new server farm), so as to achieve the best performance. We will call this approach hybrid load balancing. This approach is sometimes also used for a single performance of a balanced device does not meet the case of a large number of connection requests