How Ring Breaks Are Detected And Healed - Dell PowerConnect B-RX Configuration Manual

How ring breaks are detected and healed

Figure 67
preserves connectivity among the customer networks.
FIGURE 67
If a break in the ring occurs, MRP heals the ring by changing the states of some of the ring
interfaces:
•
•
When the broken link is repaired, the link's interfaces come up in the Preforwarding state, which
allows RHPs to travel through the restored interfaces and reach the secondary interface on the
Master node.
BigIron RX Series Configuration Guide
53-1001810-01
Shows the ring forwarding state following a link break. MRP quickly heals the ring and
Metro ring – ring break
F
F
Switch C
Customer A
Blocking interface – The Blocking interface on the Master node has a dead timer. If the dead
time expires before the interface receives one of its ring's RHPs, the interface changes state to
Preforwarding. Once the secondary interface changes state to Preforwarding:
•
If the interface receives an RHP, the interface changes back to the Blocking state and
resets the dead timer.
•
If the interface does not receive an RHP for its ring before the Preforwarding time expires,
the interface changes to the Forwarding state, as shown in
Forwarding interfaces – Each member interface remains in the Forwarding state.
How ring breaks are detected and healed
Customer A
F
F F
Switch B
Switch D
F
F
Customer A
F
Master
F
Switch A
Node
Customer A
F
Figure 67.
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