> # TE Port

> In trunking E port (TE port) mode, an interface functions as a trunking expansion port. It may be connected to another TE port to create an extended ISL (EISL) between two switches. TE ports are specific to Cisco MDS 9000 Family switches. They expand the functionality of E ports to support the following:

> - VSAN trunking
> - Transport quality of service (QoS) parameters
> - Fibre Channel trace (fctrace) feature

> In TE port mode, all frames are transmitted in EISL frame format, which contains VSAN information. Interconnected switches use the VSAN ID to multiplex traffic from one or more VSANs across the same physical link. This feature is referred to as trunking in the Cisco MDS 9000 Family switches (see "Configuring Trunking"). TE ports support class 2, class 3, and class F service.

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