Chapter 2: Bridging Configuration Guide36 SmartSwitch Router User Reference ManualMulticast-based VLANsMulticast-based VLANs are created dynamically for multicast groups. Typically, eachmulticast group corresponds to a different VLAN. This ensures that multicast frames arereceived only by those ports that are connected to members of the appropriate multicastgroup.Policy-based VLANsPolicy-based VLANs are the most general definition of VLANs. Each incoming(untagged) frame is looked up in a policy database, which determines the VLAN to whichthe frame belongs. For example, you could set up a policy which creates a special VLANfor all email traffic between the management officers of a company, so that this traffic willnot be seen anywhere else.SSR VLAN SupportThe SSR supports:• Port-based VLANs• Protocol-based VLANs• Subnet-based VLANsWhen using the SSR as an L2 bridge/switch, use the port-based and protocol-basedVLAN types. When using the SSR as a combined switch and router, use the subnet-basedVLANs in addition to port-based and protocol-based VLANs. It is not necessary toremember the types of VLANs in order to configure the SSR, as seen in the section onconfiguring the SSR.VLANs and the SSRVLANs are an integral part of the SSR family of switching routers. The SSR switchingrouters can function as layer-2 (L2) switches as well as fully-functonal layer-3 (L3) routers.Hence they can be viewed as a switch and a router in one box. To provide maximumperformance and functionality, the L2 and L3 aspects of the SSR switching routers aretightly coupled.The SSR can be used purely as an L2 switch. Frames arriving at any port are bridged andnot routed. In this case, setting up VLANs and associating ports with VLANs is all that isrequired. You can set up the SSR switching router to use port-based VLANs, protocol-based VLANs, or a mixture of the two types.The SSR can also be used purely as a router, i.e., each physical port of the SSR is a separaterouting interface. Packets received at any interface are routed and not bridged. In thiscase, no VLAN configuration is required. Note that VLANs are still created implicitly by
