Service Manual
Fabric OS 7.4.0a Release Notes v2.0 Page 50 of 53
• To connect between a switch and an HBA at 16 Gbps, both sides must be in the same mode (fixed speed,
and FEC on or off) for them to communicate at that rate. If only one port has FEC enabled, neither port will
be able to see the other. If the ports are in dynamic mode, then they may connect, but not at 16 Gbps.
NOTE: Enabling/disabling FEC is a disruptive operation
NOTE: Enabling/disabling FEC is a disruptive operationNOTE: Enabling/disabling FEC is a disruptive operation
NOTE: Enabling/disabling FEC is a disruptive operation
portCfgFec
Use this FOS CLI command to enable or disable Forward Error Correction (FEC) or Transmitter Training Signal
(TTS) on a specified port or on a range of ports, or to display the configuration.
FEC provides a mechanism for reducing error rates during data transmissions over 16 Gbps Fibre Channel
links. When FEC is enabled on a port, the sender adds systematically generated error-correcting code (ECC) to
its data transmission. This mechanism allows the receiver to detect and correct errors without needing to get
additional information from the sender.
By default, TTS is disabled switch-wide on all 16 Gbps platforms. If the TTS mode is enabled, the port
negotiates FEC through TTS. The 16 Gbps TTS is not compatible with the more commonly used 16 Gbps
64B/66B. Thus, the TTS mode should only be enabled if a similarly TTS-capable and enabled device is
connected to the port.
The Brocade implementation of FEC is supported on 16 Gbps platforms and enables the switch to recover bit
errors in 16 Gbps and 10 Gbps data streams. The FEC encoding can correct one burst of up to 11 error bits in
every 2,112-bit transmission. The error correction covers both frames and primitives. There is no loss of
bandwidth or added transmission data rate overhead to the 16 Gbps FC link.
By
ByBy
By
default,
default,default,
default,
FEC
FECFEC
FEC
is
isis
is
enabled
enabledenabled
enabled
switch
switchswitch
switch-
--
-wide
widewide
wide
on
onon
on
all
allall
all
16
1616
16
Gb
GbGb
Gbp
pp
ps
ss
s
pla
plapla
plat
tt
tforms
formsforms
forms. If FEC is already enabled on the ports,
enabling FEC has no effect. If a range of ports is specified, some of which are already in the requested
configuration, a notification is generated, and no action is taken for those ports only. All other ports in the
specified range are updated. Enabling or
Enabling orEnabling or
Enabling or
disabling FEC
disabling FECdisabling FEC
disabling FEC
is disruptive to tra
is disruptive to trais disruptive to tra
is disruptive to traf
ff
ffic.
fic.fic.
fic.
When used with the --
----
--show
showshow
show option, the command displays the following information for the specified ports:
Port
PortPort
Port
The port index number
FEC Capable
FEC CapableFEC Capable
FEC Capable
Displays YES if the port supports FEC. Displays NO if the port does not support FEC.
FEC Configured
FEC ConfiguredFEC Configured
FEC Configured
Displays ON if FEC is enabled on the port (default). Displays OFF if the feature is disabled.
FEC via TTS Configured
FEC via TTS ConfiguredFEC via TTS Configured
FEC via TTS Configured
Displays OFF if TTS is disabled on the port (default). Displays ON if the FEC negotiation via TTS feature
is enabled.
FEC State
FEC StateFEC State
FEC State
The FEC state can be active or inactive. An active FEC state indicates that FEC is enabled and actually
running. An inactive state can indicate two conditions: FEC is enabled, but not running due to some
error condition (for example, FEC may not be enabled on both ends of the link). Or FEC is disabled and
therefore inactive.
Use the portCfgShow
portCfgShowportCfgShow
portCfgShow command to display the FEC configuration along with other port parameters. Use the
islShow
islShowislShow
islShow command to view interswitch link-level FEC configurations. Use the portErrshow
portErrshowportErrshow
portErrshow and portStatShowhow
portStatShowhowportStatShowhow
portStatShowhow
commands to monitor data transmission errors. You should see a significant reduction in CRC errors on FEC-
enabled links.
FEC is supported the following links:
•
Between E_Ports on all 16 Gbps platforms running Fabric OS v7.0.0 or later. Both sides of the link must be
configured with port speeds of 10 Gbps and 16 Gbps.
•
Between F_Ports and N_Ports in Access Gateway mode (requires Fabric OS v7.1.0 and later on the AG and the
switch.