LAN bridges were architecture solutions in the early part of the company's growth. Soon the flat, bridge-based network was becoming unmanageable. Bridges merely repeat traffic from one end to the other. Some segments such as engineering and accounting wanted to conceal their traffic for bandwidth and security reasons. Hence, the flat-earth network of bridges migrated to an environment with network routers.
Network routers allow for scalability and a mixture of media.
Such a network would use the FDDI ring as a backbone to the corporate network. In this tiered network architecture, multiple routers attach to the FDDI backbone. Newer technologies have emerged, such as the optical router, gigabit router, and routing LAN switches. However, the basics really haven't changed, especially in corporate network markets. Network infrastructures are costly to remove, so the FDDI backbone I described is a legacy and predominant architecture that's still in use today.