Configuration Guide User guide

410 BigIron RX Series Configuration Guide
53-1002484-04
How ring breaks are detected and healed
14
How ring breaks are detected and healed
Figure 67 Shows the ring forwarding state following a link break. MRP quickly heals the ring and
preserves connectivity among the customer networks.
FIGURE 67 Metro ring – ring break
If a break in the ring occurs, MRP heals the ring by changing the states of some of the ring
interfaces:
• 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 Figure 67.
• Forwarding interfaces – Each member interface remains in the Forwarding state.
F
FF
Customer A
Switch B
Customer A
Customer A
Customer A
Switch A
Switch C
Switch D
Master
Node
F
F
F
F
F
F
F