Reference Guide

Enabling or disabling FEC for long-distance ports
To enable or disable FEC for long-distance ports, use portCfgLongDistance with the -fecEnable or -fecDisable parameter as required.
switch:admin> portcfglongdistance 12/6 LS 1 -distance 100 -fecenable
Refer to Managing Long-Distance Fabrics on page 483 for more details on working with long-distance ports.
Displaying and clearing the FEC counters
Both correctable and uncorrectable FEC counters help you to identify link degradation and take actions.
1. Run the portStatsShow and portStats64Show commands to display the counters.
Stinger3:FID128:root> portstatsshow 16 | grep fec
fec_cor_detected 1111 Count of blocks that were corrected by FEC
fec_uncor_detected 0 Count of blocks that were left uncorrected by FEC
Stinger3:FID128:root> portstats64show 16
…
stat64_fec_cor 0 top_int : FEC corrected errors detected
1111 bottom_int : FEC corrected errors detected
stat64_fec_uncor 0 top_int : FEC uncorrected errors detected
0 bottom_int : FEC uncorrected errors detected
NOTE
"fec_cor_detected" is displayed on Gen 5 platforms. Gen 6 platforms display "fec_uncor_detected".
2. Run the portStatsClear command to clear the counters.
FEC-via-TTS
All devices that support FEC-via-TTS have it enabled by default; however, not all devices that support 16 Gbps support FEC-via-TTS.
FEC-via-TTS is negotiated during speed negotiation when a link comes up. Any HBA or device connection that supports 16 Gbps but
not FEC-via-TTS auto-negotiates to 8 Gbps. Therefore, FEC-via-TTS must only be enabled on switch ports intended for connections to
HBAs and devices that support FEC-via-TTS. A Brocade to Brocade ISL connection does not utilize TTS to enable FEC; consequently,
FEC-via-TTS must be disabled on all E_Ports. When FEC-via-TTS is enabled on a port, the port will automatically be disabled when
connected to another Brocade 16 Gbps Gen 5 switch.
∙ FEC-via-TTS is disabled by default.
∙ When enabling FEC-via-TTS, the port is momentarily disabled and therefore is a disruptive action. FEC-via-TTS is active only
when both ends of the link have FEC enabled.
∙ E_Port connectivity is not supported when FEC-via-TTS is enabled on the switch port.
∙ DWDM devices do not support FEC-via-TTS.
∙ FEC-via-TTS is supported only on QLE267x and QLE274x with driver v9.1.14.22 and later. Prior to enabling FEC Transmitter
Training Signal (TTS) mode, refer to your HBA documentation to confirm FEC-via-TTS functionality and support.
∙ FEC-via-TTS displays ON when control of the FEC state is permitted via TTS by an externally attached host or device even if
the peer does not support it. Displays Active when FEC has been negotiated between the switch and the attached HBA or
device. Displays (..) or OFF when the external control of FEC is disabled.
FEC-via-TTS can be enabled or disabled using the CLI on a port range on a fixed-port switch or on a port range within a slot for
Directors. FEC-via-TTS is a method to negotiate FEC when FEC is supported on Gen 5 links. Therefore. FEC must be enabled as well.
1. Before executing any commands, remember to set the CLI context to the fabric ID (FID) for the logical switch. For example, to
set the context to FID 1:
switch:admin> setcontext 1
Performing Advanced Configuration Tasks
Brocade Fabric OS Administration Guide, 8.0.1
53-1004111-02 105