Table of Contents:

Definition and Overview

1. Introduction

2. Softswitch Architectural Overview

3. Network Element Failure Scenarios in the Network Office

4. High-Availability Techniques for the Network Office

5. Software Failure Analysis

6. Conclusions

Self-Test

Glossary

PDF of this tutorial

The effective deployment of the new network office must account for a variety of potential failures that we have identified. However, the likelihood of different failures should be considered when evaluating various architecture options:

• Since the network is the most frequent area for failures, a robust network architecture is a critical component of the network office—the distributed softswitch architecture.
• High availability requires multiple yet independent network paths between all components. In the event of a network path failure, communication must be re-established in a very short amount of time without sacrificing reliability. Protocols that rapidly switch communication between interfaces (e.g., SCTP) are necessary pieces of a solution.
• Software failures are overcome with redundant systems that are able to execute different software versions, yet interoperate and fail-over in a matter of seconds.
• Hardware failures are also overcome with redundant systems in a cost-effective manner. While fault-tolerant hardware does offer an additional level of comfort, its cost-benefit equation is still debatable. The additional cost may not be deemed worthwhile since the required functionality can be delivered via other mechanisms.

In conclusion, a softswitch architecture based upon redundant systems and network redundancy can deliver the high availability required of the critical next-generation network systems.