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  • 1.  OSPF router id election in JUNOS

    Posted 05-10-2012 01:07

    Hi Experts

     

    1- Hows the router id elect in OSPF implementation of JUNOS?

    2- If we change the router id then what happens? I mean OSPF will restart or what?



  • 2.  RE: OSPF router id election in JUNOS
    Best Answer

    Posted 05-10-2012 03:45

    1- Hows the router id elect in OSPF implementation of JUNOS?

     

    ospf in junos always takes router-id configured under routing-option.

    If no RID configured , it will take the lowest loopback address configured.

    If no loopback , then it will take lower IP configured among the interface.

     

    Before Junos 8.5 ( i guess ) it was mandatory to add loopback address in ospf.

     

    2- If we change the router id then what happens? I mean OSPF will restart or what?

    Ospf neighbor ship   resets every time you change RID

     

    - Arun



  • 3.  RE: OSPF router id election in JUNOS

    Posted 05-14-2012 10:29

    Hi Arun

     

    Could you please double check "If no loopback , then it will take lower IP configured among the interface" I believe it takes the physical interface IP which comes up first.

     

    Also if router-id changes then OSPF process does not restart in JUNOS so you could find LSA with old and new router-id and old LSA takes time to be flushed, which is not good I think 😉

     

    Thanks

     

     



  • 4.  RE: OSPF router id election in JUNOS

    Posted 05-14-2012 23:23

    Thanks Kashif , you are right.... 🙂



  • 5.  RE: OSPF router id election in JUNOS

    Posted 05-16-2012 13:38

    Thanks Arun and Kashif



  • 6.  RE: OSPF router id election in JUNOS

    Posted 05-03-2016 17:44

    I agree on the router-id election, but I disagree with OSPF restart. If you change Router-ID ospf restart (at least on EX4200 with Junos 12.3R3.4)

    I had recently a case in which an IP-Phone plugged into the network was restarting the OSPF relationship, causing short packet loss.

    The reaons behind is because the phone was bringing up the Voice Vlan at Layer 3, which had lower IP-address compared to the data-l3-vlan, thus it was resetting the OSPF relationship and restarting it with new router ID.

    This has been also tested in the lab, with same result.