DCFM Professional Plus User Manual (53-1001774-01, June 2010)

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• In a scenario where a FCIP tunnel has multiple circuits of different metrics the data will flow
over the lower metric circuits unless a failover condition occurs, as described in “FCIP circuit
failover capabilities”.
• The maximum bandwidth for a single circuit is 1 Gbps. To utilize the entire bandwidth of an
XGE (10GbE) port, you must create ten 1 Gbps circuits.
FCIP circuit failover capabilities
Each FCIP circuit is assigned a metric, which is used in managing failover for FC traffic. Typically,
the metric will be either 0 or 1. If a circuit fails, FCIP Trunking tries first to retransmit any pending
send traffic over another lowest metric circuit. In Figure 130, circuit 1 and circuit 2 are both lowest
metric circuits. Circuit 1 has failed, and transmission fails over to circuit 2, which has the same
metric. Traffic that was pending at the time of failure is retransmitted over circuit 2. In order
delivery is ensured by the receiving 7800 switch.
FIGURE 130 Link loss and retransmission over peer lowest metric circuit
In Figure 131, circuit 1 is assigned a metric of 0, and circuit 2 is assigned a metric of 1. In this
case, circuit 2 is a standby that is not used unless there are no lowest metric circuits available. If
all lowest metric circuits fail, then the pending send traffic is retransmitted over any available
circuits with the higher metric,
FIGURE 131 Failover to a higher metric standby circuit
7800
7800
Circuit 1
Circuit 2
213
X
13 ?
Resend 2
7800
7800
Circuit 1 - Metric 0 - Active
Circuit 2 - Metric 1 - Standby