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LDP on loopback

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  • 1.  LDP on loopback

    Posted 06-19-2021 19:51
    I noticed in some Juniper training materials, LDP is enabled on the loopback interface, but in some not.
    I roughly know LDP assignment in Juniper is different from Cisco. I like to know whether I should enable LDP on loopback or not, or any differences.

    thanks !!


  • 2.  RE: LDP on loopback
    Best Answer

     
    Posted 06-20-2021 05:42
    I have not done mpls on Cisco so can't speak to differences, but on Junos my recollection here is you need ldp on the loopback if you are using ldp over rsvp (also called targeted ldp) which is typical in larger topologies.  While if you have all your ldp signaling direct (just with connected nodes) ldp is not needed on the loopback.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------



  • 3.  RE: LDP on loopback

    Posted 06-20-2021 14:12
    thanks !!
    I came across the following from Cisco Juniper MPLS Integration Problem. - Cisco Community 
    By default, JUNOS LDP only advertises /32 loopback prefix-FEC bindings upstream, you need to explicitly configure egress policy under LDP to advertise other prefix-FEC mappings. 
    ​

    As I saw most of the Juniper training materials always include loopback in the ldp configuration. I  thought that loopback is a must in LDP configuration as Juniper assigns label only to the loopback interface except some additional configuration. But recently I came across some Juniper training materials do not include loopback in LDP configuration. That is why I am concerned anything I missed.

    I am wondering whether LDP works if no loopback configured. will test it.
    I will review JMF training again.




  • 4.  RE: LDP on loopback

     
    Posted 06-20-2021 14:47
    The basic need for loopback ldp is if your signaling needs to go through any other device.  In other words the two endpoints signaling are NOT directly connected.

    If they are directly connected then it won't be needed.

    Thus I've never seen a production ldp deploy without adding loopbacks.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------



  • 5.  RE: LDP on loopback

    Posted 06-20-2021 16:15
    thanks so much !!
    So whenever I use LDP,  I always include loopback in ldp configuration. It should not hurt anything, right ?


  • 6.  RE: LDP on loopback

     
    Posted 06-21-2021 06:11
    Sure it will do no harm to have it included.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------