Foundry NetIron M2404C and M2404F Metro Access Switches Configuring VLANs (Rev.03)
Super VLANs
© 2008 Foundry Networks, Inc.
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Super VLAN ring topology
– Suits layer 2 ring topology networks that are based on the MSTP
(Multiple Spanning Tree Protocol). Which interface on the ring will function as the uplink port is
decided by MSTP.
Super VLAN for Layer 2 Application
Super VLAN is designed for a Layer-2 switching environment where the sub-VLANs and the
Super VLAN share the same IP subnet mask. The Super VLAN provides enhanced security
between the customers, by disallowing communication between the sub-VLANs, whether or not
they are located in the same LAN. Furthermore, the configuration is simple, devoid of the
complexity of setting each customer in a different VLAN or IP subnet masking. The Super VLAN
blocks all the traffic types (unicast, broadcast and multicast) between the sub-VLANs.
Use the
super-vlan
command in Interface Configuration mode to set the Super VLAN.
Super VLAN for Ring Topology
When using MSTP, in order to implement ring topology, the traffic can flow either clockwise or
counterclockwise. The two ports that are connected to the ring are referred to as uplink ports, while
the rest of the ports are referred to as user ports. The Super VLAN ring topology feature is used
when the Super VLAN port has to be the root port of the bridge. In this case it must be one of the
uplink ports (for all the ring bridges except for the root bridge). When Super VLAN ring topology
is configured, the Super VLAN uplink port is chosen dynamically by the bridge between the two
uplink ports. If a topology change occurs, the Super VLAN uplink changes automatically and the
new root port will be chosen as a Super VLAN uplink port.
Figure 11: Super VLAN Ring Mode Configuration Example