Junos OS

  • 1.  Loopback on Junos

    Posted 04-28-2011 21:38

    Hey all,


    I found that in SXR240 juniper service gateway could not create many loopbacks (lo0, lo1,lo2...) as we can in IOS. only lo0 available to use. is that the same on all Juniper products ? if so what is the advantage to use only one loopback  interface ?





  • 2.  RE: Loopback on Junos
    Best Answer

    Posted 04-29-2011 06:06


    Yes only 1 loopback interface called lo0 is available in JUNOS.

    However, one can create many units (how many is platform dependent) on lo0 and put these units into different routing-instances.

    This means that if you don't have routing-instances at all you can use only single unit on lo0. You can also assign many IP addresses to this single unit if you need these IP addresses to be always reachable.

    BTW, loopback interface in JUNOS does not really loop back packets, unlike IOS loopback interface. Implications are: you cannot have NAT assigned to JUNOS loopback, you cannot have a dial-peer pointing at JUNOS loopback etc.

    In a nutshell, JUNOS loopback and IOS loopback interfaces are fundamentally different.



  • 3.  RE: Loopback on Junos

    Posted 04-29-2011 07:29

  • 4.  RE: Loopback on Junos

    Posted 04-29-2011 07:50



    good to know that ...thanks.

    I find that i'm falling in love with Junos.