Network Sales and Services Handbook (Cisco Press Networking Technology)
The following topics are covered in this chapter:
Measuring Network Availability
Internetwork Reliability Options
The term high availability can be nebulous to define because the term itself is considered subjective; what one person or network provider considers to be "high availability" does not necessarily mean the same for another person or network service provider.
High availability is a subjective interpretation of two network availability statistics:
Mean-Time-to-Repair (MTTR) Average time required to recover/restore from a network outage or repair a failed component.
Mean-Time-Between Failure (MTBF) Average time a network or component works without failure.
This chapter discusses measuring network availability and reliability in addition to the building of redundant networks.