User's Manual

286
Users Manual of CS-6306R
Figure 5: Intersection of the major ring and the sub ring
When trouble occurs on the link of the major ring, and when the channel of the sub-ring protocol packets
between the edge node and the assistant node are interrupted, the master node of the sub ring cannot
receive the HELLO packets that the master node itself transmits. In this case, the Fail Time times out, and the
master node of the sub ring changes to the Failed state and opens its secondary port.
The above-mentioned processes have an effective protection towards general networking, guaranteeing not
only the prevention of the broadcast loopback but also the corresponding functions of the backup link. The
dual homing networking mode is always used in actual networking, as shown in the following figure. The two
sub rings in the dual homing networking, sub ring I and sub ring II, interconnect through the edge node and
assistant node, and forms a big ring. When the major ring has troubles, the secondary ports of the master
nodes of all sub rings open and forms the broadcast loop (marked by the arrow) in the big ring.
Figure 6: Broadcast storm triggered by the dual homing networking mode