27.2.1 Network Configuration

(1) Single ring configuration

The following figure shows a single ring configuration.

A single ring configuration consisting of one master node and multiple transit nodes is called a single ring configuration. The nodes in the ring are connected as ring ports by physical ports or link aggregations. Note that the same VLAN must be used as the control VLAN for all nodes in the ring, and a common VLAN must be used for data frame transfer. Control frames sent from the master node are circulated within the control VLAN. The VLANs used to send and receive data frames are aggregated into a single logical group called a VLAN group. VLAN groups can group multiple VLANs, and set a maximum of two groups for clockwise and counter-clockwise circulation in a single ring from the master node.

(2) Multi-ring configuration

Of the possible multi-ring configurations, the following figure shows one in which a single node is the contact point for the neighboring ring.

Each node in the ring runs as a single independent ring. Therefore, ring fault detection and recovery detection are performed independently by each ring.

(3) Multi-ring configuration with shared link

Of the possible multi-ring configurations, the following figure shows one in which multiple nodes are the contact points for the neighboring ring.

When multiple single rings are connected by multiple nodes, links are shared by multiple rings. These links are called shared links, and multi-ring configuration with these links is called a multi-ring configuration with shared links. On the other hand, when, as in (2), multiple single rings are connected by a single node, because no shared links exist, this is called a multi-ring configuration without shared links.

(4) Virtual link

In a device that can use Ring Protocol and Spanning Tree Protocols together, two devices on a ring network that have both functions are connected by a virtual line. This virtual line is called a virtual link. A virtual link has a virtual link VLAN for sending and receiving control frames between virtual links. The virtual link VLAN is assigned one of the data transfer VLAN and communicates virtual link control frames and flush control frames on this VLAN. Although the Switch does not support virtual links, if there is a device using Ring Protocol and Spanning Tree Protocols on a ring network that uses the Switch as a transit node, the Switch forwards virtual link control frames and receives flush control frames only.