Routing

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Ask questions and share experiences about ACX Series, CTP Series, MX Series, PTX Series, SSR Series, JRR Series, and all things routing, including portfolios and protocols.
  • 1.  OSPF Loopback Interface passive

    Posted 24 days ago
    Hello.
     
    I have a question about OSPF.
     
    Many people specify passive when they include Loopback Interface in OSPF.
    (set protocols ospf area 0 interface lo0 passive)
     
    I understand that even if you do not set the passive on the loopback interface, OSPF Message is not created and Route is advertised in the local LSDB with LSA Type1 Stub Type.
    In other words, I think the same action is done without setting the passive.
     
    What's the problem if I don't configure passive on the loopback interface??
     
    If you don't specify passive, I'm also wondering if the equipment uses resources to create an ospf message.


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    YOON JUN CHOI
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  • 2.  RE: OSPF Loopback Interface passive

    Posted 20 days ago

    Ran a test in a small 3 router lab where I removed the passive on the loopback for one of the routers.

    There was no change in either the OSPF database or the routing table.

    The interface status did change from the state DRother to DR.  



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    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
    http://puluka.com/home
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  • 3.  RE: OSPF Loopback Interface passive

    Posted 17 days ago
    • If you don't specify passive, I'm also wondering if the equipment uses resources to create an ospf message.

    Sure, it will forever attempt to form a neighborship by sending OSPF Hello messages. That neighborship will never get established. JUNOS won't get... tired... but it's useless to keep sending them forever.