29.1.2 Key Features

(1) Ethernet-based ring network

The Ring Protocol is an Ethernet-based network redundancy protocol. Whereas conventional ring networks typically use dual-link fiber optics such as with FDDI, the Ring Protocol can be used to build ring networks using Ethernet.

The following figure shows an example Ring Protocol application.

Figure 29-2 Application of Ring Protocol (Part 1)

Figure 29-3 Application of Ring Protocol (Part 2)

(2) Simple operation method

Networks using the Ring Protocol have a simple configuration consisting of one master node and other transit nodes. Ring status monitoring (for faults and fault restoration) and path switching is primarily performed by the master node, and the other transit nodes perform path switching according to instructions from the master node.

(3) Control frame

The Ring Protocol uses its own control frames. These control frames are used for monitoring the ring status by the master node, and in instructions for path switching from the master node to transit nodes. Because control frame sending and reception is performed on a special VLAN, data frames and control frames are not sent within the same VLAN, unlike normal Spanning Tree Protocols. Also, because control frames are given processing priority, an increase in data traffic will not impact control frames.

(4) Load-Balancing Methods

Multiple VLANs used within a ring are aggregated logically by group, and data can be set to be balanced clockwise or counter-clockwise from the master node. This is useful for load balancing and dividing paths by VLAN.