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Configuring a Bridge Domain

A bridge domain must include a set of logical interfaces that participate in Layer 2 learning and forwarding. You can optionally configure a VLAN identifier and a routing interface for the bridge domain to also support Layer 3 IP routing. For more detailed information about how to configure IRB for a bridge domain, see Configuring Integrated Routing and Bridging for a Bridge Domain. To enable a bridge domain, include the following statements:



[edit]

bridge-domains {



bridge-domain-name {

domain-type bridge:

vlan-id (none | all | number);

vlan-tags outer number inner number);

interface interface-name;

routing-interface routing-inteface-name;
}


}
protocols {
mstp ...
}

For the vlan-id statement, you can specify either a valid VLAN identifier or the none or all options. For information about VLAN identifiers and VLAN tags for a bridge domain, see Configuring VLAN Identifiers for a Bridge Domain or a VPLS Routing Instance.

To include one or more logical interfaces in the bridge domain, specify an interface-name for an Ethernet interface you configured at the [edit interfaces] hierarchy level.

Note: A maximum of 4000 active logical interfaces are supported on a bridge domain or on each mesh group in a virtual private LAN service (VPLS) instance configured for Layer 2 bridging.

By default, each bridge domain maintains a Layer 2 forwarding database that contains media access control (MAC) addresses learned from packets received on the ports that belong to the bridge domain. You can modify Layer 2 forwarding properties, including disabling MAC learning for the entire system or a bridge domain, adding static MAC addresses for specific logical interfaces, and limiting the number of MAC addresses learned by the entire system, the bridge domain, or a logical interface. For more information about how to configure Layer 2 forwarding properties for a bridge domain, see Configuring Layer 2 Learning and Forwarding Properties for a Bridge Domain. For more information about how to configure Layer 2 forwarding properties for a set of bridge domains with a Layer 2 trunk port, see Configuring Layer 2 Learning and Forwarding Properties for a Set of Bridge Domains with a Layer 2 Trunk Port. You can also configure Layer 2 address learning and forwarding properties for an MX-series router as a whole. For more information, see Configuring Layer 2 Address Learning and Forwarding Properties.

You can also configure spanning-tree protocols to prevent forwarding loops at the [edit protocols mstp] hierarchy level. For more information, see Configuring Spanning-Tree Protocols.

Beginning with JUNOS Release 8.5, you can configure IGMP snooping for a bridge domain. For more information, see the JUNOS Multicast Protocols Configuration Guide.

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