Introduction

The Internet and Internet services have become increasingly important to businesses over time, and several organizations are choosing to implement measures to keep these services highly available to their staff or to their customers. The first task is identifying which services are business critical, and then determining the best solution to keep that service available 99.9 percent of the time. The reason that keeping a service available is an issue at all is because the Internet and networking technology is not fail-proof. Your ISP connection could be down or slow, your internal router could lose its routing table and stop passing packets, or you could have a hardware failure or power failure at any point in the network infrastructure, which could cause any number of service interruptions.

So, what can you do to prevent these outages from happening? Well, you probably can't control them 100 percent of the time, regardless of how much time, money, and effort you put into the project, but you can make a considerable dent in downtime by setting up some redundant systems and configuring them to fail over in the event of a failure.

For example, your company prints a well-known newspaper on the East Coast, and having the Internet available to your reporters is business critical, since they use this source of information for many of their articles. Therefore, it's your job to have a redundant Internet connection with fail-over abilities. You could contract two ISPs, have two routers set up at each...