31.1.1 Overview

The Ring Protocol and a Spanning Tree Protocol can be used together on the same device, to configure a network that uses the Ring Protocol for the core network and a Spanning Tree Protocol for the access network. For example, when a network consists entirely of Spanning Tree Protocols and only the core network is changed to the Ring Protocol, a significant share of existing facilities for the access network can be diverted without any changes. Note that the Ring Protocol can be used with Spanning Tree Protocols for both single rings and multi-rings (including multi-rings with shared links).

The figures below give examples of the Ring Protocol being used with Spanning Tree Protocols for single ring configurations or multi-ring configurations. The Spanning Tree topology consists of Switch A-G-I, B-F-J, and C-D-K. In Switches A to D and F to G, both Ring Protocol and Spanning Tree Protocols operate simultaneously.

Figure 31-1 Simultaneous use of Ring Protocol and Spanning Tree (Single ring configuration)

Figure 31-2 Combination of Ring Protocol and Spanning Tree (Multi-ring Configuration)