Configuring Integrated Routing and Bridging for VLANs
Integrated routing and bridging (IRB) provides simultaneous support for Layer 2 bridging and Layer 3 routing on the same interface. IRB enables you to route packets to another routed interface or to another VLAN that has an IRB interface configured. You configure a logical routing interface by specifying irb as an interface name at the [edit interfaces] hierarchy level and including that interface in the VLAN.
 | Note: You can include only one Layer 3 interface in a VLAN. |
To configure a VLAN with IRB support, include the following statements:
For each VLAN that you configure, specify a vlan-name. You must also specify the value bridge for the domain-type statement.
For the vlan-id statement, you can specify either a valid VLAN identifier or the none option.
| Note: If you configure a Layer 3 interface to support IRB in a VLAN, you cannot use the all option for the vlan-id statement. |
The vlan-tags statement enables you to specify a pair of VLAN identifiers; an outer tag and an inner tag.
| Note: For a single VLAN, you can include either the vlan-id statement or the vlan-tags statement, but not both. |
To include one or more logical interfaces in the VLAN, specify the interface-name for each Ethernet interface to include that you configured at the [edit interfaces] hierarchy level.
| Note: A maximum of 4096 active logical interfaces are supported for a VLAN or on each mesh group in a VPLS routing instance configured for Layer 2 bridging. |
To associate a Layer 3 interface with a VLAN, include the l3-interface interface-name statement and specify an interface-name you configured at the [edit interfaces irb] hierarchy level. You can configure only one Layer 3 interface for each VLAN.
IRB interfaces are supported for multicast snooping.
In multihomed VPLS configurations, you can configure VPLS to keep a VPLS connection up if only an IRB interface is available by configuring the irb option for the connectivity-type statement at the [edit routing-instances routing-instance-name protocols vpls] hierarchy level. The connectivity-type statement has the ce and irb options. The ce option is the default and specifies that a CE interface is required to maintain the VPLS connection. By default, if only an IRB interface is available, the VPLS connection is brought down.
| Note: When you configure IRB interfaces in more than one logical system on a device, all of the IRB logical interfaces share the same MAC address. |
