Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 83)

• If an RHP reaches the Master node secondary interface, the ring is intact. The secondary interface
changes to Blocking. The Master node sets the forwarding bit on in the next RHP. When the restored
interfaces receive this RHP, they immediately change state to Forwarding.
• If an RHP does not reach the Master node secondary interface, the ring is still broken. The Master
node does not send an RHP with the forwarding bit on. In this case, the restored interfaces remain in
the Preforwarding state until the preforwarding timer expires, then change to the Forwarding state.
If the link between shared interfaces breaks ( Figure 9 ), the secondary interface on Ring 1 master node
changes to a preforwarding state. The RHP packet sent by port 3/1 on Ring 2 is forwarded through the
interfaces on S4, then to S2. The packet is then forwarded through S2 to S3, but not from S2 to S1
since the link between the two nodes is not available. When the packet reaches Ring 1 master node,
the packet is forwarded through the secondary interface since it is currently in a preforwarding state. A
secondary interface in preforwarding mode ignores any RHP packet that is not from its ring. The
secondary interface changes to blocking mode only when the RHP packet forwarded by its primary
interface is returned.
The packet then continues around Ring 1, through the interfaces on S1 to Ring 2 until it reaches Ring 2
master node. Port 3/2, the secondary interface on Ring 2 changes to blocking mode since it received its
own packet, then blocks the packet to prevent a loop.
FIGURE 9 Flow of RHP packets when a link for shared interfaces breaks
RHP packets follow this flow until the link is restored; then the RHP packet returns to it normal flow as
shown in
Figure 7 on page 81.
Master VLANs and customer VLANs
All the ring ports must be in the same VLAN. Placing the ring ports in the same VLAN provides Layer 2
connectivity for a given customer across the ring. The following figure shows an example.
Master VLANs and customer VLANs
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