Brocade Network Advisor SAN User Manual v12.3.0 - Manual (Page 991)

Brocade Network Advisor SAN User Manual 939
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FCIP trunking
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The following actions occur during circuit failures:
• If either circuit 0 or circuit 1 fails, traffic flows over the remaining circuit while the failed circuit
is being recovered. The available bandwidth is still considered to be 1.5 Gbps.
• If both circuit 0 and circuit 1 fail, there is a failover to circuits 2 and 3, and the available
bandwidth is updated as 2 Gbps.
• If a low metric circuit becomes available again, the high metric circuits return to standby
status, and the available bandwidth is updated again as each circuit comes online. For
example, if circuit 0 is recovered, the available bandwidth is updated as 1 Gbps. If circuit 1 is
also recovered, the available bandwidth is updated as 1.5 Gbps.
Circuit Failover Grouping
With Circuit Failover Grouping you can better control which metric 1 circuits will be activated if a
metric 0 circuit fails. For this feature, you define a set of metric 0 and metric 1 circuits that are part
of the same failover group. When all metric 0 circuits in the group fail, metric 1 circuits will take
over data transfer, even if there are metric 0 circuits still active in other failover groups.
Typically, you would only define one metric 0 circuit in the group so that a specific metric 1 circuit
will take over data transfer when the metric 0 fails. This will also avoid the problem of the tunnel
operating in a degraded mode with less than the defined circuits before multiple metric 0 circuits
fail.
Configure failover groups using the Add FCIP Circuit dialog box. Refer to “Adding an FCIP circuit” on
page 962 for instructions.
Considerations and limitations
Failover groups operate under the following conditions;
• Each failover group is independent and operates autonomously.
• All metric 0 circuits in a group must fail before the metric 1 circuits are used.
• All metric 1 circuits in a group are used if all metric 0 circuits in the group fail or there is no
metric 0 circuit in the group.
• Circuits can be part of only one failover group
• Failover circuit groups are only supported at Fabric OS v7.2.0 or greater.
• Both ends of the FCIP tunnel must have the same failover circuit groups defined for the feature
to function properly.
• When a tunnel activates or circuits are modified, tunnel and circuit states will indicate a
misconfiguration error if failover circuit group configurations are not valid.
• Modifying of the failover group ID is a disruptive operation, similar to modifying the metric.
• Circuit failover groups are not used to define load balancing over metric 0 circuits, (ONLY
failover rules). Circuits of metric 0 will be load balanced over regardless of failover grouping.
• When no FCIP circuit failover groups are defined, failover reverts to default operation - all
metric 0 circuits must fail before failing over to metric 1 circuit(s). In order to change default
failover operation, a failover group should include at least one metric 0 and at least metric 1
circuit.