Brocade Network Advisor SAN User Manual v11.1x (53-1002167-01, May 2011)

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FCIP trunking

• 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. However, a maximum of 10 Gbps per

circuit is allowed between 10 GbE ports on 8 Gbps Extension Blades when both blades are

running Fabric OS 7.0 or greater.

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 283, 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 8 Gbps Extension Switch.

FIGURE 283 Link loss and retransmission over peer lowest metric circuit

In Figure 284, 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 284 Failover to a higher metric standby circuit

Bandwidth calculation during failover

The bandwidth of higher metric circuits is not calculated as available bandwidth on an FCIP tunnel

until all lowest metric circuits have failed. For example, assume the following:

7800

Circuit 1

Circuit 2

213

13 ?

Resend 2

7800

Circuit 1 - Metric 0 - Active

Circuit 2 - Metric 1 - Standby