Disaster Recovery Journal

 Server load balancing ensures application availability, facilitates tighter application integration, and intelligently and adaptively load balances user traffic based on a suite of application metrics and health checks. It also load balances IPS/IDS devices and composite IP-based applications and distributes HTTP(S) traffic based on headers and SSL certificate fields.

The primary function of server load balancing is to provide availability for applications running within traditional datacenters, public cloud infrastructure, or a private cloud. Should a server or other networking device become over-utilized or cease to function properly, the server load balancer redistributes traffic to healthy systems based on IT-defined parameters to ensure a seamless experience for end users.

In today’s highly virtualized environments, modern application delivery controllers not only ensure application availability and performance, they are also capable of integrating with virtualization management software to spin up and spin down virtual resources as needed to ensure availability of resources to meet the demands of end users.

 Link load balancing addresses WAN reliability by directing traffic to the best performing links. Should one link become inaccessible due to a bottleneck or outage, the ADC takes that link out of service, automatically directing traffic to other functioning links.

Where server load balancing provides availability and business continuity for applications and infrastructure running within the data center, link load balancing ensures uninterrupted connectivity from the datacenter to the Internet and telecommunications networks.

Link load balancing may be used to send traffic over whichever link or links prove to be most cost-effective for a given time period. What’s more, link load balancing may be used to direct select user groups and applications to specific links to ensure bandwidth and availability for business critical functions.

 Geographical load balancing pro-
vides reliability between geographically
dispersed data centers. ADCs redirect traf-
fic to the best performing sites based on
latency, site performance, and user loca-
tion. Global load balancing delivers high
availability; if one site goes down, traffic
will automatically redirect to other work-
ing sites.

 SSL transactions consume server CPU cycles due to intensive encryption and decryption of the packets on a repeated basis. ADCs offload SSL from servers, allowing them to focus on serving applications and content to end-users, improving availability and response times on the servers.

The National Institute of Standards and Technology (NIST) has mandated that businesses transition from 1028-bit SSL encryption to the more secure 2048-bit standard. Tests indicate that 2048-bit SSL encryption is 500 percent more resource intensive than 128-bit encryption. The result is that existing infrastructure will likely become bogged down supporting the new standard, impacting availability and the user experience for critical business processes.

Modern application delivery controllers
support high-performance hardware accel-
eration for 2048-bit SSL encryption, often
at prices equivalent to previous-genera-
tion 1024-bit encryption. Whether secure
applications are running on dedicated
servers in a traditional data center environ-
ment or on virtualized infrastructure in a
public or private cloud, it is advantageous
to offload process-intensive 2048-bit SSL
encryption to dedicated hardware to pro-
vide the highest level of application secu-
rity, availability, and performance.

 TCP acceleration offloads connections and sessions in several ways to optimize data flows and reduce the impact on servers, preventing them from being overloaded.

Mobile traffic is increasingly outpacing traditional network traffic. Mobile traffic also uses far more connections and opens and closes connections far more often than traditional network traffic. Over time, legacy data center equipment will be unable to keep pace, and application availability will suffer.

TCP acceleration supported on modern application delivery controllers offloads connections from servers, handles a far greater number of concurrent connections, and has the ability to handle far greater connections every second. Modern application delivery controllers also have the ability to multiplex thousands of client side connections into a much smaller number of larger server-side connections, greatly increasing efficiency and further improving the availability and performance enterprise applications and cloud services.

From ensuring the availability, performance and security of applications, servers and other devices within the data center, to ensuring reliable connectivity to global networks, to ensuring the availability of business processes under worst-case scenarios, application delivery controllers can and should play a significant role in an organization’s business continuity plan. Whether deployed in traditional data centers or in public or private clouds, modern application delivery controllers provide the features and performance needed to ensure business continuity while at the same time improving efficiencies, supporting next-generation standards, and preparing organizations for growing trends in the areas of mobile and cloud computing.

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Sunil Cherian is the vice president of product marketing at Array Networks (www. arraynetworks.com). He has more than 15 years of experience in the networking field and has served in various technical and marketing capacities for Alteon WebSystems, Lucent, Octel, and VMX. Cherian holds a bachelor’s degree in computer science and engineering from College of Engineering, Thiruvananthapuram, India, and a master’s in computer science from the State University of New York, Albany, N. Y.