> # Key Concepts

> The trunking feature includes the following key concepts:

> - TE port—If trunk mode is enabled in an E port and that port becomes operational as a trunking E port, it is referred to as a TE port.
> - TF port—If trunk mode is enabled in an F port and that port becomes operational as a trunking F port, it is referred to as a TF port.
> - TN port—If trunk mode is enabled (not currently supported) in an N port and that port becomes operational as a trunking N port, it is referred to as a TN port.
> - TNP port—If trunk mode is enabled in an NP portand that port becomes operational as a trunking NP port, it is referred to as a TNP port.
> - TF PortChannel—If trunk mode is enabled in an F PortChannel and that PortChannel becomes operational as a trunking F PortChannel, it is referred to as TF PortChannel. Cisco Port Trunking Protocol (PTP) is used to carry tagged frames.
> - TF-TN port link—A single link can be established to connect an F port to an HBA to carry tagged frames using Exchange Virtual Fabrics Protocol (EVFP). A server can reach multiple VSANs through a TF port without inter-VSAN routing (IVR).
> - TF-TNP port link—A single link can be established to connect an TF port to an TNP port using the PTP protocol to carry tagged frames . PTP is used because PTP also supports trunking PortChannels.

> Note The TF-TNP port link between a third-party NPV core and a Cisco NPV switch is established using the EVFP protocol.

> - A Fibre Channel VSAN is called Virtual Fabric and uses a VF_ID in place of the VSAN ID. By default, the VF_ID is 1 for all ports. When an N port supports trunking, a pWWN is defined for each VSAN and called a logical pWWN. In the case of MDS core switches, the pWWNs for which the N port requests additional FC_IDs are called virtual pWWNs.

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