Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 526)

496 Multi-Service IronWare Switching Configuration Guide
53-1003036-02
MRP Phase 2
14
The primary interface of the master node initiates RHP packets and sends them onto the ring.
When the packet reaches a forwarding interface, MRP checks to see if the receiving interface is a
regular interface or a tunnel interface:
• If the interface is a regular interface, the RHP packet is forwarded to the next interface.
Forwarding of the packet continues on the ring until the secondary interface of the master
node receives the packet and processes it. For the configured ring the receipt of an RHP with
the same ring ID indicates the ring is healthy. RHPs for lower priority rings will be discarded
without further processing at this point.
• If the interface is a tunnel interface, MRP checks the priority of the RHP packet and compares
it to the priority of the tunnel interface:
• If the RHP packet’s priority is less than or equal to the interface’s priority, the packet is
forwarded through ring interfaces with higher priority which are in the forwarding state.
• If the priority of the RHP packet is greater than the priority of the interface, the RHP packet
is dropped. For example, if an RHP with a ring ID of 1 arrives at a tunnel interface owned by
ring 2 the RHP will be dropped. If an RHP with a ring ID of 2 or 3 arrives at a tunnel
interface owned by ring 2 the RHP will be forwarded.
NOTE
It is important to understand the key concept of RHPs leaking from lower priority rings to higher
priority rings. Always remember that tunnel interfaces check the ring ID of an RHP before forwarding.
Higher priority ring ID RHPs will be dropped.
How ring breaks are detected and healed between
shared interfaces
If the link between shared interfaces breaks, the secondary interface on the highest priority ring
master node changes to a preforwarding state, refer to
Figure 123 . Any RHP from lower priority
rings can traverse this interface and thus maintain the integrity of the lower priority rings. When the
secondary interface changes state to forwarding the lower priority ring RHP’s continue to traverse
the interface.
This behavior allows the ring 2 RHP’s to continue around ring 1 and back to ring 2 until it reaches
the secondary interface on ring 2’s master node which changes to blocking mode since it receives
its own RHP.
NOTE
On the ring member node, the primary and secondary interface is decided by the RHP flow from the
ring master. The secondary interface is always the RHP receiver for its ring RHP’s, the primary
interface is always the sender of its rings RHP’s. If there is no active ring master in the topology, then
the running configuration on the member node will show exactly what was configured. This may
change on introduction of an active ring master.