EMC DS-16B manual Operating Mode, Operating modes are determined by the host adapter. The six

Switch Management

Operating Mode		The operating modes are determined by the host adapter. The six
		operating modes for the switch are:
Table 3-5		Operating Mode Definitions
	Mode		Description
	Non-SCSI Tachyon Mode		When set, multiple sequences from different sources are interleaved to
			Tachyon-based controllers at Sequence boundaries rather than at
			frame boundaries, resulting in better performance from Tachyon-based
			controllers.
	Isolated Operation		Setting this mode isolates the switch from the rest of the Fabric.
	Disable Device Probing		When this is set, devices that do not register themselves with the Name
			Server will not be present in the Name Server data base.
	VC-Encoded Address Mode		When this mode is set, frame source and destination addresses utilize
			an address format compatible with some first-generation switches.
	Disable Translative Mode		The setting is only relevant if VC Encoded Address Mode is also set.
			When set, this maintains explicit address compatibility with some first-
			generation switches.
	Per-Frame Route Priority		In addition to the eight virtual channels used in frame routing priority,
			support is also available for per-frame based prioritization when this
			value it set. When set, the virtual channel ID will be used in conjunction
			with a frame header to form the final virtual channel ID.
		The administrator determines the adapter in use, then sets the switch
		for the corresponding operating mode.
Virtual Channels		The switch provides the ability to tune the switch in a specific
		application.

The first two virtual channels are reserved for the switch’s internal functions and are not available.

The default virtual channel settings are already optimized for switch performance. Changing the default values, if properly selected, may improve switch performance somewhat, but may also severely degrade performance. You should not change these settings without fully understanding the change’s effects.

Departmental Switch Model DS-16B Hardware Reference Manual