Trunk Modes

By default, trunk mode is enabled on all Fibre Channel interfaces (Mode: E, F, FL, Fx, ST, and SD) on non-NPV switches. On NPV switches, by default, trunk mode is disabled. You can configure trunk mode as on (enabled), off (disabled), or auto (automatic). The trunk mode configuration at the two ends of an ISL, between two switches, determine the trunking state of the link and the port modes at both ends (see Table 9-2).

Table 9-2 Trunk Mode Status Between Switches
Your Trunk Mode Configuration			Resulting State and Port Mode
Port Type	Switch 1	Switch 2	Trunking State	Port Mode
E ports	On	Auto or on	Trunking (EISL)	TE port
	Off	Auto, on, or off	No trunking (ISL)	E port
	Auto	Auto	No trunking (ISL)	E port
Port Type	Core Switch	NPV Switch	Trunking State	Link Mode
F and NP ports	On	Auto or on	Trunking	TF-TNP link
	Auto	On	Trunking	TF-TNP link
	Off	Auto, on, or off	No trunking	F-NP link

Tip The preferred configuration on the Cisco MDS 9000 Family switches is one side of the trunk set to auto and the other side set to on.

Note When connected to a third-party switch, the trunk mode configuration on E ports has no effect. The ISL is always in a trunking disabled state. In the case of F ports, if the third-party core switch ACC's physical FLOGI with the EVFP bit is configured, then EVFP protocol enables trunking on the link.