Global Server Load Balancing

You can delete or modify existing health check policies.

To configure how often the health check is performed by default, use the global configuration setting healthcheck.update.interval (default value is 600 seconds). You can override this value for an individual health check policy.

For details on how to set a health check policy using the UI, see Section 16.8.1, “Adding a Load Balancer Rule”.

16.9. Global Server Load Balancing

CloudPlatform supports Global Server Load Balancing (GSLB) functionalities to provide business continuity by load balancing traffic to an instance on active zones only in case of zone failures. CloudPlatform achieves this by extending its functionality of integrating with NetScaler Application Delivery Controller (ADC), which also provides various GSLB capabilities, such as disaster recovery and load balancing. The DNS redirection technique is used to achieve GSLB in CloudPlatform.

In order to support this functionality, region level services and service provider are introduced. A new service 'GSLB' is introduced as a region level service. The GSLB service provider is introduced that will provider the GSLB service. Currently, NetScaler is the supported GSLB provider in CloudPlatform. GSLB functionality works in an Active-Active data center environment.

16.9.1. About Global Server Load Balancing

Global Server Load Balancing (GSLB) is an extension of load balancing functionality, which is highly efficient in avoiding downtime. Based on the nature of deployment, GSLB represents a set of technologies that is used for various purposes, such as load sharing, disaster recovery, performance, and legal obligations. With GSLB, workloads can be distributed across multiple data centers situated at geographically separated locations. GSLB can also provide an alternate location for accessing a resource in the event of a failure, or to provide a means of shifting traffic easily to simplify maintenance, or both.

16.9.1.1. Components of GSLB

A typical GSLB environment is comprised of the following components:

•GSLB Site: In CloudPlatformterminology, GSLB sites are represented by zones that are mapped to data centers, each of which has various network appliances. Each GSLB site is managed by a NetScaler appliance that is local to that site. Each of these appliances treats its own site as the local site and all other sites, managed by other appliances, as remote sites. It is the central entity in a GSLB deployment, and is represented by a name and an IP address.

•GSLB Services: A GSLB service is typically represented by a load balancing virtual server in a zone. In a GSLB environment, you can have a local as well as remote GSLB services. A local GSLB service represents a local load balancing or content switching virtual server. A remote GSLB service is the one configured at one of the other sites in the GSLB setup. At each site in the GSLB setup, you can create one local GSLB service and any number of remote GSLB services.

•GSLB Virtual Servers: A GSLB virtual server refers to a logical grouping of one or more GSLB services. CloudPlatform GSLB functionality ensures that traffic is load balanced across VMs in multiple zones. It evaluates the configured GSLB methods or algorithms to select a GSLB service to which to send the client requests. One or more virtual servers from different zones are bound to the GSLB virtual server. GSLB virtual server does not have a public IP associated with it, instead it will have a FQDN DNS name.

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Citrix Systems 4.2 manual About Global Server Load Balancing, Components of Gslb
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4.2 specifications

Citrix Systems, a leading provider of virtualization solutions and cloud computing technologies, released version 4.2 of its popular software, Citrix XenApp, which was previously known as Presentation Server. This version marked a significant evolution in providing users with remote access to applications and desktops, emphasizing simplicity, performance, and security.

One of the standout features of Citrix XenApp 4.2 is its improved application streaming capabilities. This technology allows applications to be delivered to users in real-time, reducing the need for extensive local installations and enhancing the user experience. With application streaming, administrators can efficiently manage applications on a central server while ensuring that users have immediate access to the necessary tools.

Another highlight of this version is the enhanced security measures put in place to protect sensitive data. Citrix XenApp 4.2 includes support for SSL encryption, providing a secure communication channel for data transmitted between the server and clients. This is particularly crucial for businesses that need to comply with strict data protection regulations. Additionally, the integration of endpoint security features ensures that unauthorized access to applications is minimized.

Performance enhancements are also a critical focus in this release. Citrix optimized the delivery of applications over various network conditions, ensuring that users experience minimal latency regardless of their location. This was achieved through the incorporation of SmartAccess and SmartControl technologies, which allow administrators to set policies based on user roles, device types, and network conditions. This level of granularity enables organization-wide security without compromising on usability.

The user experience was further improved with a revamped interface, making it easier for end-users to access their applications and data. Simplified menus, clear navigation paths, and the ability to customize user settings contributed to a more efficient workflow, allowing users to focus on their tasks rather than struggling with the software.

Finally, Citrix XenApp 4.2 was designed to be highly scalable. Organizations of all sizes could deploy this solution to deliver applications efficiently, adapting to their specific needs as their user base grows or changes. This flexibility is crucial for businesses looking to future-proof their IT investments while maintaining optimal performance.

In summary, Citrix XenApp 4.2 stands out with its enhanced application streaming, robust security features, improved performance under varying conditions, user-friendly interface, and scalability, making it an ideal choice for organizations seeking to leverage virtualization for remote access to applications and desktops.
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