Section 2.1.d (ii) dot1Q
Recall that in section 2.1.c we showed the 802.1q header and discussed all of the fields within, so I won’t go over that again.
Instead we will discuss choosing the encapsulation on a port.
On most newer switches, we only have the option of 802.1q, but older switches also support ISL.
Configuring static trunks on those required the command
switchport trunk encapsulation dot1q
if you wanted ISL encap you would use
switchport trunk encapsulation ISL