Overview
Business today has an increasing reliance on data networks to deliver services required for business operations. Many of these services now rely upon the data network to provide inventory control, accounts receivable and payable, order processing, and the many other aspects of running a business efficiently. The need for timely and accurate data is driving the demand for high network availability and reliability.

Most network administrators and designers underestimate the importance of the Spanning-Tree Protocol (STP). As routers became popular in the early 1990s, STP faded into the background as a "less important protocol that just worked." However, with the recent rise of switching technology, Spanning Tree has once again become an important factor that can have a tremendous impact on your network's performance. In fact, STP often accounts for more than 50 percent of the configuration, troubleshooting, and maintenance headaches in real-world campus networks (especially if they are poorly designed). This chapter covers the mechanics of the Spanning-Tree Protocol as it performs its basic loop-prevention duties.

This chapter discusses techniques and technologies within a campus network that are targeted at increased network reliability. An overview of the technologies associated with campus redundancy and the implementation of Cisco solutions to ensure network availability is presented. Additionally, this chapter covers the following topics:

  • Spanning-Tree Protocol Operations and Processes
  • Spanning Tree in a VLAN environment
  • Scaling the Spanning-Tree Protocol