NetScaler is a high performance network device, expected to be able to handle several gigabytes of traffic per second while being highly available given how critical enterprise applications are. To ensure optimal performance, NetScaler is generally integrated very tightly into the network, and where there is such integration involved, there is naturally a potential for issues during the deployment stage. Such issues are the focus of this chapter.
The two main areas we'll look at in this chapter are:
- High Availability issues
- Networking issues
For many environments that use it, NetScaler becoming unavailable means losing access to a fleet of web applications, and even access to the corporate network in the case of NetScaler Gateway deployments. So it is little wonder that, when NetScaler is deployed in an enterprise, it is always deployed in High Availability (HA) pairs.
In a properly set up HA pair environment, the standby NetScaler, which we refer to as the secondary in this chapter, jumps into action within milliseconds of detecting a failure and announces its intention to become the primary. If the network is fast in adapting itself to the change of ownership, traffic gets restored within seconds of the failure.
In the next few pages, we will look at the various facets of HA before diving into troubleshooting.