Should a router need to know VLAN information?

johnifanx98

http://www.dell.com/downloads/global/products/pwcnt/en/app_note_38.pdf

As instructed above when using a router to do inter-VLAN routing, we need to configure VLANs on the router as on switches. This does not sound very elegant. If a router needs to know VLAN, then it's not a layer 3 device, rather than a hybrid of L2 & L3...

chrisone

the VLANs on a router are sub-interfaces. You need IP address on those sub-interfaces to route between VLANs. So that trunk between the router and the switch , passes VLAN information. You need a router to pass traffic between different networks (VLAN Networks). However on a router there is no switchport mode trunk command, that is only on the switch. On the router you make a trunk by creating sub-interfaces on the interface where the switch and router use. The sub-interfaces use a command "encapsulation dot1q <VLAN ID #> where you enter the VLAN ID that sub-interface will respond to.

Hope this helps clear things up.

Also...dont use Dell for network studies

MrXpert

Another name for the above is called "router on a stick". Have a look for the Cisco guide online for this topic if needed