Configuring Aggregated VLANs

To configure aggregated VLANs, perform the following tasks:

• On each edge device, configure a separate port-based VLAN for each client connected to the edge device. In each client VLAN:
  • Add the port connected to the client as an untagged port.
  • Add the port connected to the core device (the device that will aggregate the VLANs) as a tagged port. This port must be tagged because all the client VLANs share the port as an uplink to the core device.
• On each core device:
  • Enable VLAN aggregation. This allows the core device to add an additional tag to each Ethernet frame that contains a VLAN packet from the edge device. The additional tag identifies the aggregate VLAN (the path). However, the additional tag can cause the frame to be longer than the maximum supported frame size.
  • To allow frames larger than 1522, you must enable jumbo frames. To globally enable jumbo support, enter commands such as the following.

    device(config)# jumbo
    device(config)# write memory
    device(config)# end
    device# reload

    Note: Enable the VLAN aggregation option only on the core devices.
• Configure a VLAN tag profile (tag ID) that is different than the tag profile used on the edge devices. If you use the default tag profile (8100) on the edge devices, set the tag profile on the core devices to another value, such as 9100. The tag profile must be the same on all the core devices. The edge devices also must have the same tag profile but the profile must be different from the tag profile on the core devices.