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VRF on EX with IRB only

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  • 1.  VRF on EX with IRB only

    Posted 04-22-2020 05:21


    I'm trying to configure different routing-instances for certain IRBs on an EX4600. I've got one IRB  dedicated for management purposes (i.e. ssh connections) that should use routing-instance r1 (type: virtual router) and everything else should use routing instance r2 (also virtual router). Since all vlans arrive via the same trunk port I can't use physical ports in the vrf configuration like in this example: The very moment I commit the changes the ssh session becomes unresponsive, so I guess management services need to use the default instance 🙂

    Can anybody point me in the right direction?

  • 2.  RE: VRF on EX with IRB only
    Best Answer

    Posted 04-22-2020 09:30

    Hello Jet_Jaguar,


    The option I can think now is to set the interface irb in the routing-instance instead of physical port.  The situation with this is that all VLANs should have a l3-interface to route traffic since the physical port should be removed from both routing instances and stay in the default instance.


    Another options is using the management interface.  Starting in Junos OS 17.3R1, you can confine the management interface in a dedicated management instance by configuring the management-instance configuration statement at the [edit system] hierarchy level. 


    Here is the documentation if you want to check this option.







  • 3.  RE: VRF on EX with IRB only

    Posted 04-27-2020 06:40

    Hey Randall,

    thank you for your response. Using only the IRBs doesn't work for some reason, so we'll be stuck with the management interface.

    Best Regards,

  • 4.  RE: VRF on EX with IRB only

    Posted 04-28-2020 02:53

    The irb interface is assocated with some vlan and physical ports as well.  So without physical ports that are up/up the irb interface will be down.


    From your description I think the interface you want is the loopback interface.  These are lo0 as the name with units

    set interface lo0 unit 0 family inet address

    set interface lo0 unit 1 family inet address


    And then put these interfaces into your routiing instance


  • 5.  RE: VRF on EX with IRB only

    Posted 04-28-2020 02:57

    Hi spuluka,

    thank you, I've taken that into account. For me it boils down to this: Do we have to use physical ports in an routing instance of the type virtual-router or are irb interfaces sufficent?

    Best Regards,

  • 6.  RE: VRF on EX with IRB only

    Posted 04-28-2020 03:01

    irb interfaces must have physical interfaces associated they will not work alone.


  • 7.  RE: VRF on EX with IRB only

    Posted 04-28-2020 03:09

    I agree, the irbs need physical interfaces bound to them. But then a separate routing-instance can work with irbs alone (which have to be up), right?