If you set to 3 everything will work after negotiating primitives.  On Thursday, August 29, 2013, Sridhar246
Looks like Brocade is recommending setting 8Gb SAN ports to mode3 for the fillword setting.  What I am trying to determine is there a way to set eitehr all ports or all ports on a blade to this or is it a port level command only.  Having to go thru 6 blades with 64 ports on a DCX and set this individually is a decent effort; not to mention I have about 9 DCX chassis.  Best practice guideline for 8G FC platforms. For Brocade 8G platforms running FOS v6.3.1 or higher, configuring the fill word to mode 3 typically enables the port to use the right combination of Fibre Channel primitives to fully interoperate with the attached end the link between the Brocade 8G switch port and the end device. If a device is known to require mode 2 (IDLE/ARB) then configuring mode 2 on the 8G switch port will activate the link sooner. If mode 3 is used in this environment, then the port will first attempt mode 1 then eventually settle to mode 2 which will cause a delay in initializing the port. If a device requires IDLE/IDLE combination for link initialization then one needs to set the needed port to mode 0 using portcfgfillword CLI.
setting portcfgfillword to mode 3