> # 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.

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