Fabric OS Administrator’s Guide 417
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Bottleneck detection 18
NOTE
Bottleneck detection is disabled by default. Best practice is to enable bottleneck detection on all
switches in the fabric, and leave it on to continuously gather statistics.

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 both 4 Gbps and 8 Gbps platforms.
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 418 for additional information on using
bottleneck detection in VF mode.

How bottlenecks are reported

Bottlenecks are reported through RASlog alerts and SNMP traps. You can set alert thresholds for
the severity and duration of the bottleneck.
You can also use a CLI command to display a history of bottleneck conditions on a port. A history is
maintained for a maximum of three hours for each port.

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.