Brocade BigIron RX Series Configuration Guide - Manual (Page 486)

408 BigIron RX Series Configuration Guide
53-1002484-04
Ring initialization
14
FIGURE 65 Metro ring – initial state
MRP uses Ring Health Packets (RHPs) to monitor the health of the ring. An RHP is an MRP protocol
packet. The source address is the MAC address of the master node and the destination MAC
address is a protocol address for MRP. The Master node generates RHPs and sends them on the
ring. The state of a ring port depends on the RHPs.
A ring interface can have one of the following MRP states:
• Preforwarding (PF) – The interface can forward RHPs but cannot forward data. All ring ports
being in this state when you enable MRP.
• Forwarding (F) – The interface can forward data as well as RHPs. An interface changes from
Preforwarding to Forwarding when the port’s preforwarding time expires. This occurs if the port
does not receive an RHP from the Master, or if the forwarding bit in the RHPs received by the
port is off. This indicates a break in the ring. The port heals the ring by changing its state to
Forwarding. The preforwarding time is the number of milliseconds the port will remain in the
Preforwarding state before changing to the Forwarding state, even without receiving an RHP.
• Blocking (B) – The interface can process RHPs, but cannot forward data. Only the secondary
interface on the Master node can be Blocking.
Customer A
Customer A
Customer A
Customer A
Switch B
Switch A Switch C
Switch D
F
F
F
F
PF
PF
PF PF
PF PF
PF
PF
All ports start in
Preforwarding state.
Primary port on Master
node sends RHP 1
Master
Node