Brocade BigIron RX Series Configuration Guide - Manual (Page 499)

BigIron RX Series Configuration Guide 421
53-1002484-04
Ring initialization for shared interfaces
14
When the RHP packet from Ring 2 reached S2, it was also forwarded from S2 to S3 on Ring 1 since
the port on S2 has a higher priority than the RHP packet. The packets is forwarded around Ring 1
until it reaches port 2/2, Ring 1’s the secondary port. The RHP packet is then blocked by that port.
Flow when a link breaks
If the link between shared interfaces breaks ( Figure 74 ), the secondary interface on Ring 1’s
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’s 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’s 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 74 Flow of RHP packets when a link for shared interfaces brakes
RHP packets follow this flow until the link is restored; then the RHP packet returns to it normal flow
as shown in
Figure 74 .
NOTE
There should always be a layer 2 protocol configured in the default VLAN when MRP is configured
with all dual mode ports.
X
Ring 1
Ring 2
S3
S4
S1
S2
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
1,2
1,2
Master node
port2/2 changes
to preforwarding
(primary interface) port2/1
Master node
port3/2
port3/1 (primary interface)
= Ring 2 RHP packet
T
T