Ok, i know what they are. Am used to use them from extreme networks.

Just seem not to be able to get them going on mikrotik.

How are vlan ports on different other ports connected? I mean, I only see ports, not the vlan definition itself:

add arp=enabled comment="Hosting Frontbone Vlan" disabled=no interface=\
loopback l2mtu=65531 mtu=1500 name=loopback.0999 use-service-tag=yes \
vlan-id=999

That does not define the "vlan itself".

If I want to add the vlan with id 999 to another port, will I just add another with the same ID? WIll those hook up (i.e. is there a "hidden" VLAN 999 that then uses all ports that use this id?). In extemen etworks you create the VLAN manually, assign an ip there, THEN add ports... a little confused.

Second, how does that work togethe with bridges? What is the differnce bwtween 2 ethernet ports with a bridge and the vlan port on the bridge, and 2 ethernet ports with the VLAN port on every ethernet port? What is more efficient?

Third, can I assign an ip adress to a vlan? I tried... did not work. I moved an existing IP assignment from a b ridge to the vlan, moved the vlan without tag to the bridge... could not ping. What did I do wrong?

Ok, i got it. a VLAN in Mikrotik is just an ethernet card. Multiple VLANS dont share anything. If I want it to run left and right.... I need to put in a bridge and add them to the bridge.