Cisco Catalyst LAN Switching

This chapter covers the following key topics:

• Transparent Bridging This section explains the five main processes of transparent bridging. These include Forwarding, Flooding, Filtering, Learning and Aging.

• Switching Modes Various switching modes such as store-and-forward, cut through and others are compared and contrasted.

• Token Ring Bridging Different methods exist for bridging Token Ring. This section describes your options.

• Token Ring Switching Token Ring switching provides many of the benefits found in Ethernet switching. This section discusses rules for Token Ring switching in a Catalyst environment

• Ethernet or Token Ring Some users are installing new network systems and do not know which to use. This section provides some thoughts for making the selection

• Migrating Token Ring to Ethernet Administrators frequently elect to replace legacy Token Ring systems with Fast Ethernet switched solutions. This section offers suggestions of things to consider in such an upgrade.

Although various internetworking devices exist for segmenting networks, Layer 2 LAN switches use bridge internetworking technology to create smaller collision domains. Chapter 2, "Segmenting LANs," discussed how bridges segment collision domains. But bridges do far more than segment collision domains: they protect networks from unwanted unicast traffic and eliminate active loops which otherwise inhibit network operations. How they do this differs for Ethernet and Token Ring networks. Ethernet employs transparent bridging to forward traffic and Spanning Tree to control loops. Token Ring typically uses a process called source-route bridging. This chapter describes transparent bridging, source-route bridging (along with some variations), and Layer 2 LAN switching. Chapter 6 covers Spanning Tree for Ethernet.