> # General Guidelines and Limitations

> The trunking feature has the following general configuration guidelines and limitations:

> - F ports support trunking in Fx mode.
> - The trunk-allowed VSANs configured for TE, TF, and TNP links are used by the trunking protocol to determine the allowed active VSANs in which frames can be received or transmitted.
> - If a trunking enabled E port is connected to a third-party switch, the trunking protocol ensures seamless operation as an E port.
> - Trunking F ports and trunking F PortChannels are not supported on the following hardware:
> - 91x4 switches, if NPIV is enabled and used as the NPIV core switch.
> - Generation 1 2-Gbps Fibre Channel switching modules.
> - On core switches, the FC-SP authentication will be supported only for the physical FLOGI from the physical pWWN.
> - No FC-SP authentication is supported by the NPV switch on the server F ports.
> - MDS does not enforce the uniqueness of logical pWWNs across VSANs.
> - DPVM is not supported on trunked F port logins.
> - The DPVM feature is limited to the control of the port VSAN, since the EVFP protocol does not allow changing the VSAN on which a logical pWWN has done FLOGI.
> - The port security configuration will be applied to both the first physical FLOGI and the per VSAN FLOGIs.
> - Trunking is not supported on F ports that have FlexAttach enabled.
> - On MDS 91x4 core switches, hard zoning can be done only on F ports that are doing either NPIV or trunking. However, in NPV mode, this restriction does not apply since zoning is enforced on the core F port.

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