- Category: 軟件
- Author: Admin
- July 19,2017
Before diving into the concepts of Global Server Load Balancing, let us first discuss in brief the importance of load balancing. Load balancers are required to distribute the data traffic between multiple servers. Suppose you have a server with a website hosted on it. As the website gains popularity, more and more users start accessing it. The server becomes incapable of hosting such amount of traffic. The solution for it is to deploy another server to host the website. To balance the traffic between these two servers, a load balancer is required. There are both hardware and software based load balancers available in the market.
Load balancing is a technique to balance the traffic between multiple servers and to route the request to the servers on the basis of various defined algorithms. Some of the algorithms deployed are Round Robin, Least Connections. IP Harsh etc. Nowadays
Global Server Load Balancing
Global load balancing is the load balancing technique where the servers are distributed geographically. The server may be located in various parts of a country, continent or even different continents. Global load balancing is achieved with the help of a Global Traffic Manager(GTM).
The Global Traffic Manager is an intelligent solution used to make informed decisions about the routing of the requests on the basis on DNS.
Imagine you have servers in multiple data centers all across the globe. You have data centers in the regions of Asia, Africa and North America. How will the request coming from a user be routed to the most suitable location?
This is done with the help of Global Traffic Manager. The Global Traffic Manager resolves the Fully Qualified Domain Name(FQDN) of the request and makes a decision on which location the request should be sent. The servers located in the same geographical area are managed by the Local Traffic Manager(LTM). The servers are divided in a pool of servers managed by the Local Traffic Manager(LTM). There might be several servers under an LTM and several LTMs under a GTM.
When a user requests for a site, it Local DNS server contacts the GTM of the website, which then routes it to the LTM of the most suitable geographical location. The LTM moves the process further by routing the request to the most suitable server.
There are various algorithms that are followed to make an intelligent and informed decision. Some of them are discussed below.
The requests are sent sequentially to the locations. If the first request has been routed to the first pool, the second request will necessarily be routed to the second pool. It is not a very simple method and not a preferred one for Global Server Load Balancing.
Weighted Round Robin
The server pools are given assigned weights based on specific considerations. The routing is done on the basis on these pools.
When a user sends a request, the GTM identified the location of the request and sends the request to the nearest location's LTM.
The performance of any web-based application is judged by scalability, response time and support. Global ServerLoad Balancing has become absolutely pivotal in this day and age due to its wide reach geographically and the ease by which scalability can be achieved through it.