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.