User's Manual

Table Of Contents
287
Users Manual of CS-6306R
The channel status checkup mechanism of the sub-ring protocol packet on the major ring is introduced to
solve the problem about the dual homing ring. This mechanism is to monitor the status of the channel link on
the major ring between the edge node and the assistant node, which requires the help of the edge node and
the assistant node. The purpose of this mechanism is to keep the data loop from happening by blocking the
edge port of the edge node before the secondary port of the master node on the sub ring opens. The edge
node is the trigger of the mechanism, while the assistant node is the listener and decider of this mechanism.
Once the notification message from the edge node cannot be received, the edge node will instantly be in
blocked state until this notification message is received again. The results of the mechanism, which bring
about after the troubles on the major ring, are shown in the following figure:
Figure 7: Results of the channel status checkup mechanism
But you should pay special attention to this point that the edge port of the assistant node must be blocked
before the secondary port of the master node on the sub ring opens. Otherwise, the broadcast storm will
happen.
The whole procedure of this mechanism is described as follows:
1. Check the channel status on the major ring between the edge node and the assistant node.
The edge node of the sub ring periodically transmits the Edge-Hello packets to the major ring through the two
ports of the major ring, and these packets pass through all nodes on the major ring in sequence and finally
arrive the assistant node, as shown in the following figure. If the assistant node can receive the edge-hello
packet in the regulated time, it indicates that the channel of this packet is normal; if not, it indicates that the
channel is interrupted. The edge-hello packet is the control packet of the sub ring, but is transmitted and
received by the ports on the major ring and is transferred to the sub ring for processing.