Traditional Layer 2 switching environments consist of Layer 2 devices (such as switches) that partition data into broadcast domains. The broadcast domains can be created through physical topologies or logically through virtual local area networks (VLANs). For MX-series routers, you can logically configure broadcast domains within virtual switch routing instances, VPLS routing instances, or bridging domains. The individual routing instances or bridging domains are differentiated through VLAN identifiers and these instances or domains function much like traditional VLANs.
For detailed information and configuration instructions on bridging domains and spanning tree protocol, see the JUNOS Network Interfaces Configuration Guide, the JUNOS Routing Protocols Configuration Guide, and the JUNOS Feature Guide.
In a VPLS routing instance or bridge domain, when a frame is received from a CE interface, it is flooded to the other CE interfaces and all of the VE interfaces if the destination MAC address is not learned or if the frame is either broadcast or multicast. If the destination MAC address is learned on another CE device, such a frame is unicasted to the CE interface on which the MAC address is learned. This might not be desirable if the service provider does not want CE devices to communicate with each other directly.
To prevent CE devices from communicating directly include the no-local-switching statement. If the no-local-switching statement is configured, frames arriving on a CE interface are sent to VE or core-facing interfaces only.
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no-local-switching;
You can include this statement at the [edit bridge-domains bridge-domain-name] hierarchy level. The no-local-swithcing statement is only available on MX-series routing platforms.