IRB interfaces

Integrated routing and bridging (IRB) interfaces enable inter-subnet forwarding. Network-instances of type mac-vrf are associated with a Layer 3 network-instance of type ip-vrf or type default via an IRB interface.

On SR Linux, IRB interfaces are named irbN, where N is 0 to 255. Up to 4095 subinterfaces can be defined under an IRB interface. An ip-vrf network instance can have multiple IRB subinterfaces, while a mac-vrf network instance can refer to only one IRB subinterface.

IRB subinterfaces are type routed and cannot be configured as any other type.

IRB subinterfaces operate in the same way as other routed subinterfaces, including support for the following:

  • IPv4 and IPv6 ACLs

  • DSCP based QoS (input and output classifiers and rewrite rules)

  • Static routes and BGP (IPv4 and IPv6 families)

  • IP MTU (with the same range of valid values as Ethernet subinterfaces)

  • All settings in the subinterface/ipv4 and subinterface/ipv6 containers. For IPv6, the IRB subinterface also gets an IPv6 link local address

  • BFD

  • Subinterface statistics

IRB interfaces do not support sFlow or VLAN tagging.

IRB interface configuration

The following example configures an IRB interface. The IRB interface is operationally up when its admin-state is enabled, and its IRB subinterfaces are operationally up when associated with mac-vrf and ip-vrf network instances. At least one IPv4 or IPv6 address must be configured for the IRB subinterface to be operationally up.

--{ candidate shared default }--[  ]--
# info interface irb1
    interface irb1 {
        description IRB_Interface
        admin-state enable
        subinterface 1 {
            admin-state enable
            ipv4 {
                admin-state enable
                address 192.168.1.1/24 {
                }
            }
        }
    }