VLAN Clarification

[hairfarmer]

Would someone please clarify the difference between assigning VLANs to a Bridge vs VLANs to an interface?

I can get the VLANs to work when I assign them to a bridge but not if I assign them to an interface. A similar (but old) post http://forum.mikrotik.com/t/configuring-vlan-trunking-on-mt-router-to-cisco-c2924-switch/21509/1

/interface vlan
add arp=enabled disabled=no interface=> bridge1 > l2mtu=1594 mtu=1500 name=
“vlan214 - PCs” use-service-tag=no vlan-id=214
add arp=enabled disabled=no interface=> bridge1 > l2mtu=1594 mtu=1500 name=
“vlan215 - unroutable” use-service-tag=no vlan-id=215

Vs

/interface vlan
add arp=enabled disabled=no interface=> ether01 > l2mtu=1594 mtu=1500 name=
“vlan214 - PCs” use-service-tag=no vlan-id=214
add arp=enabled disabled=no interface=> ether01 > l2mtu=1594 mtu=1500 name=
“vlan215 - unroutable” use-service-tag=no vlan-id=215

I have a Cisco Catalyst 3500XL switch with a RouterBoard 1100.

Trunk Port Config (from memory)

FastEthernet 0/1
switchport mode trunk
switchport trunk encapsulation dot1q

I could not get this thing to work unless I put the VLANs on bridge1???

I understand that tagging happens when packets leave a VLAN interface, but how does a packet leave a bridged interface on that VLAN?

Thanks in advance

[fewi]

Can you post a network diagram and more info on what you’re trying to do?

VLANs on a physical interface work fine for routers in a stick, where the router is the layer 3 gateway for multiple VLANs. It can then route between all the VLANs, and other physical ports. Bridges only come into play when the router also acts as a layer 2 device.

[JJCinAZ]

When an Ethernet interface is “captured” by a bridge then a VLAN on the interface itself will be become ineffective and the VLAN’s master interface must be changed to the bridge. The VLAN does not automatically “move” to the bridge.