Load Balancer is a software solution for distributing incoming
client requests across servers. It boosts the performance of servers by directing
TCP/IP session requests to different servers within a group of servers; in
this way, it balances the requests among all the servers. This load balancing
is transparent to users and other applications. Load Balancer is useful for
applications such as e-mail servers, World Wide Web servers, distributed parallel
database queries, and other TCP/IP applications.
When used with Web servers, Load Balancer can help maximize the potential
of your site by providing a powerful, flexible, and scalable solution to peak-demand
problems. If visitors to your site can not get through at times of greatest
demand, use Load Balancer to automatically find the optimal server to handle
incoming requests, thus enhancing your customers’ satisfaction and your profitability.
What are the advantages to using Load Balancer?
The
number of users and networks connected to the global Internet is growing exponentially.
This growth is causing scalability problems that can limit users’ access to
popular sites. Currently, network administrators are using numerous methods
to try to maximize access. With some of these methods, you can choose a different
server at random if an earlier choice is slow or not responding. This approach
is cumbersome, annoying, and inefficient. Another method is standard round-robin,
in which the domain name server selects servers in turn to handle requests.
This approach is better, but still inefficient because it forwards traffic
without any consideration of the server workload. In addition, even if a server
fails, requests continue to be sent to it. The need for a more powerful solution
has resulted in Load Balancer. It offers numerous benefits over earlier and
competing solutions:
- Scalability: As the number of client requests increases, you can
add servers dynamically, providing support for tens of millions of requests
per day, on tens or even hundreds of servers.
- Efficient use of equipment: Load balancing ensures that each group
of servers makes optimum use of its hardware by minimizing the hot-spots that
frequently occur with a standard round-robin method.
- Easy integration: Load Balancer uses standard TCP/IP protocols.
You can add it to your existing network without making any physical changes
to the network. It is simple to install and configure.
- Low overhead Using a simple MAC level forwarding method, the Dispatcher
component looks at the inbound client-to-server flows only. It does not need
to see the outbound server-to-client flows. This significantly reduces its
impact on the application compared with other approaches and can result in
improved network performance.
- High availability: The Dispatcher
component offers built-in high availability, utilizing a backup machine that
remains ready at all times to take over load balancing if the primary server
machine fails. When one of the servers fails, requests continue to be serviced
by the other server. This process eliminates any server as a single point
of failure and makes the site highly available.
- Client to server affinity: The
affinity feature maps a client IP address to a back-end server, providing
a higher level of efficiency by decreasing the memory and CPU utilization
when compared to traditional connection forwarding.
- Load balancing a private network:
You can set up Dispatcher and the TCP server machines using a private network.
This configuration can reduce the contention on the public or external network
that can affect performance.
- Learn how you can manage servers using
Load Balancer.
Load Balancer balances traffic among your servers through
a unique combination of load balancing and management software. All client
requests sent to the Dispatcher machine are directed to the ″best″ server
according to weights that are set dynamically. You can use the default values
for those weights or change the values during the configuration process.
Dispatcher
can also detect a failed server and forward traffic around it. Dispatcher
supports HTTP, FTP, SSL, SMTP, NNTP, IMAP, POP3, Telnet, SIP, and any other
TCP based application.
Load Balancer is the key to stable, efficient management of a
large, scalable network of servers. You can link many individual servers into
what seems to be a single, virtual server. Your site is presented as a single
IP address to the world. Dispatcher functions independently of a domain name
server; all requests are sent to the IP address of the Dispatcher machine.
Dispatcher
brings distinct advantages in balancing traffic load to clustered servers,
resulting in stable and efficient management of your site.