Specifications

ALAXALA Ring Configuration Guide (Edition 1)

2.2 Single ring operation

This section describes how the Ring Protocol works in a single ring.

2.2.1 Normal operation

During normal operation, the Ring Protocol works in a single ring as follows:

Figure 2.2-1 Normal single ring operation

(1) Master node operation

The master node sends out control frames called health-check frames (HC) from each of its two ring ports over

the control VLAN. Then the master node monitors whether HCs come back from both directions within a

pre-determined time interval. Data frames are sent from the primary port to data transfer VLANs. Because the

secondary port is logically blocked, the port does not transfer data frames or learn any MAC addresses.

・ If the master node does not receive HCs in both directions within the pre-determined time interval, the

node determines that a failure has occurred.

・ A user can define the time interval.

・ After a failure occurred, when one of the ring ports receives one or more HCs, the master node

determines that the failure has been resolved.

The master node monitors whether HCs sent by the node come back. Even if some packets are lost and never

come back for some reason, the master node keeps the normal ring status as long as it can receive HCs in at least

one direction. The master node can also detect failures due to a down link in one direction and take actions when

UDLD is used or when the auto-negotiation functionality is used for connection.

(2) Transit node operation

Transit nodes do not monitor HCs sent by the master node. When a transit node receives an HC, the node

transfers the frame to the next node in the ring. Both ring ports are used to transfer data frames.

M: Master node

T1 - T5: Transit node

HC: Health-check frame

Secondary port

Ring VLAN: BLK

Primary port

Ring VLAN: FWD

Data on the data transfer VLAN

HC on the control VLAN

T2 T3 T4