Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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Fault Detection and Recovery
ExtremeWare 7.2e Installation and User Guide 185
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Polling response
Link Down Message Sent by a Transit Node
When any transit node detects a loss of link connectivity on any of its ring ports, it immediately sends a
“link down” message on the control VLAN using its good link to the master node.
When the master node receives the “link down” message (see Figure 30), it immediately declares a
“failed” state and opens its logically blocked secondary port on all the protected VLANs. Now, traffic
can flow through the master’s secondary port. The master node also flushes its FDB and sends a
message on the control VLAN to all of its associated transit nodes to flush their forwarding databases as
well, so that all of the switches can learn the new paths to layer 2 end stations on the reconfigured ring
topology.
Ring Port Down Event Sent by Hardware Layer
When a ring port goes down on a master node switch, it is notified by the lower hardware layer and
immediately goes into a “failed” state.
If the primary ring port goes down, the secondary port is opened. The normal operation of flushing its
FDB and sending a “link-down” message to all transit nodes is performed.
Polling
The master node transmits a health-check packet on the control VLAN at a user-configurable interval
(see Figure 29). If the ring is complete, the master node will receive the health-check packet on its
secondary port (the control VLAN is not blocked on the secondary port). When the master node
receives the health-check packet, it resets its failtimer and continues normal operation.
If the master node does not receive the health-check packet before the failtimer interval expires, and the
failtime expiry action is set to
o
pen the secondary port when the failtimer expires, it declares a “failed”
state. The switch then performs the same steps described above: it unblocks its secondary port for
access by the protected VLANs, flushes its forwarding database (FDB), and sends a “flush FDB”
message to its associated transit nodes.
To change the expiry timer action, use the following command:
configure eaps <name> failtime expiry-action [ open-secondary-port | send-alert]
To change the duration of the failtime, use the following command:
configure eaps <name> failtime [<seconds>]
Restoration Operations
The master node continues sending health-check packets out its primary port even when the master
node is operating in the failed state. As long as there is a break in the ring, the fail-period timer of the
master node will continue to expire and the master node will remain in the failed state.
When the broken link is restored, the master will receive its health-check packet back on its secondary
port, and will once again declare the ring to be complete. It will logically block the protected VLANs on
its secondary port, flush its FDB, and send a “flush FDB” message to its associated transit nodes.