Fabric OS Administrator's Guide v7.0.0 (53-1002148-02, June 2011)

302 Fabric OS Administrator’s Guide

53-1002148-02

Supported configurations for bottleneck detection

Note the following configuration rules for bottleneck detection:

• Bottleneck detection is supported only on Fibre Channel ports and FCoE F_Ports.

• Bottleneck detection is supported only on the following port types:

- E_Ports

- EX_Ports

- F_Ports

- FL_Ports

• F_Port and E_Port trunks are supported.

• Long distance E_Ports are supported.

• FCoE F_Ports are supported.

• Bottleneck detection is supported on 4-Gbps, 8-Gbps, and 16-Gbps platforms, including

10-Gbps speeds.

• Bottleneck detection is supported in Access Gateway mode.

• Bottleneck detection is supported whether Virtual Fabrics is enabled or disabled. In VF mode,

bottleneck detection is supported on all fabrics, including the base fabric. See “Virtual Fabrics

considerations for bottleneck detection” on page 303 for additional information on using

bottleneck detection in VF mode.

Limitations of bottleneck detection

Using this feature for latency bottleneck detection is not recommended for link utilizations above

85%.

The bottleneck detection feature detects latency bottlenecks only at the point of egress, not

ingress. For example, for E_Ports, only the traffic egressing the port is monitored. For FCoE ports,

bottleneck detection monitors traffic going from the FC side to the CEE side, and does not monitor

traffic going in the reverse direction.

High availability considerations for bottleneck detection

The bottleneck detection configuration is maintained across a failover or reboot; however,

bottleneck statistics collected are lost.

Upgrade and downgrade considerations for bottleneck detection

The bottleneck detection configuration is persistent across firmware upgrades and downgrades.

The sub-second latency criterion parameter settings are not preserved on downgrade to firmware

versions earlier than Fabric OS 7.0.0. If you downgrade and then upgrade back to Fabric OS 7.0.0,

the settings revert to their default values.