|In the Cisco world you make a port a trunk by enabling 802.1q on it.|
On my Avaya switches (Nortel) you set it to "trunk' mode which is basically means setting the port to "tag all" (as in tag all VLAN's - an "untagged" port would be for a client connection)
A quick google search of "netgear gs748s trunk port configuration" lead to the following:
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.