> # Trunking Protocols

> The trunking protocol is important for trunking operations on the ports. The protocols enable the following activities:

> - Dynamic negotiation of operational trunk mode.
> - Selection of a common set of trunk-allowed VSANs.
> - Detection of a VSAN mismatch across an ISL.

> Table 9-1 specifies the protocols used for trunking and channeling.

> Table 9-1 Supported Trunking Protocols
> Trunk Link | Default
> --- | ---
> TE-TE port link | Cisco EPP (PTP)
> TF-TN port link1 | FC-LS Rev 1.62 EVFP
> TF-TNP port link | Cisco EPP (PTP)
> E or F PortChannel | Cisco EPP (PCP)
> TF Port Channel | Cisco EPP (PTP and PCP)
> Third-party TF-TNP port link1 | FC-LS Rev 1.62 EVFP

> 1These features are not currently supported.

> By default, the trunking protocol is enabled on E ports and disabled on F ports. If the trunking protocol is disabled on a switch, no port on that switch can apply new trunk configurations. Existing trunk configurations are not affected. The TE port continues to function in trunk mode, but only supports traffic in VSANs that it negotiated with previously (when the trunking protocol was enabled). Also, other switches that are directly connected to this switch are similarly affected on the connected interfaces. In some cases, you may need to merge traffic from different port VSANs across a non-trunking ISL. If so, disable the trunking protocol.

> Note We recommend that both ends of a trunking link belong to the same port VSAN. On certain switches or fabric switches where the port VSANs are different, one end returns an error and the other end is not connected.

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