Applications must be able to process data, and that data must be available to other applications or users. When considering availability, network design engineers must evaluate the network design to locate potential bottlenecks or single points of failure that can interrupt data processing and movement, then add redundancy or make changes to the network topology to mitigate those possible faults.
For example, consider a network connection between an application server and a switch. Normally the two devices would be connected through a single link, but this presents a series of points that can fail and disconnect the server — rendering the application inaccessible. To improve availability, it might be prudent to add a second NIC to the application server and implement a redundant connection between the new NIC and another switch port (even a port available on a second switch). The trick is to understand the network architecture and the role of the application in the client’s business.
It’s important to note that there are no “high-availability network components,” only product features and attributes that can aid performance. Application availability across the network is achieved through correct network design choices that leverage relevant technologies. Techniques like connection trunking, server clustering, storage area networks (SANs), server virtualization and storage virtualization are just a few of the technologies that can help to ensure application availability.
Applications also tend to accumulate on the network over time, and the collective demands of older applications may limit the network capacity available to newer or more important applications.
When it comes to availability, redundancy is every bit as important as speed. An enterprise network must be architected to eliminate single points of failure between servers, storage and core application users. This includes the use of redundant network links to support trunking for greater performance and failover capability to compensate for faulty links. Redundant links are utilized in the LAN and SAN, and can also extend to multiple WAN links handled by different service providers.
Enterprises are becoming more distributed, routinely including multiple data centers, branch offices and remote users. Consequently, the ability to remotely access applications and their data is an increasingly important aspect of application availability, and WAN optimization and application acceleration products are finding a supporting role in the client’s network. WAN optimization typically uses some combination of data compression and TCP/IP traffic manipulation (such as jumbo frames and fewer application handshakes) to pass more data within a given bandwidth.
These technologies save money by avoiding the demand for more bandwidth. In addition, WAN optimization products allow your clients to consolidate resources by moving duplicate equipment and applications from remote sites back into the data center — applications can then be deployed to the entire user base through a single highly available network configuration.