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  • 1.  ISIS No Route-Through

    Posted 11-28-2022 12:38
      |   view attached
    Good morning everyone,

    I have an ISIS Scenario that I need assistance with and I'm trying to get some expert opinions on this.     I have a router connected to two Label Switch routers.   All three are running ISIS.  In the scenario, the two LSR's have a 300 Gbps link between them and each as a 100Gbps link to the lone router in this scenario.    I'm trying to prevent the LSR's from using the 100Gbps links through the lone router as a backup to the 300Gbps link.  

    Currently I have each of the 100 Gbps links configured in a separate ISIS instance (in this example 5 & 6), but it seems that the logs are showing LSR database issues.   I'm trying to see what my alternatives here would be.   Any thoughts?  Please let me know if you need any additional information.

    I have attached a drawing of the topology in this scenario.

    Thank you!
    Chuck

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    CHARLES MAYES
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    Attachment(s)

    pdf
    Drawing1.pdf   41 KB 1 version


  • 2.  RE: ISIS No Route-Through

    Posted 11-29-2022 05:37

    If you never want a router to be used as a transit path then just set the overload bit in the LSPDUs generated by it, so on R1 in this case.

    That would be a hard "you cannot send traffic via me" signal to the two LSRs.

    There are various other option available under the overload config depending on your needs (can have it act more like overload in OSPF where it just sets max metrics and there are also option to allow route leaking etc)

    https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/ref/statement/overload-edit-protocols-isis.html



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    STUART RIDSDALE
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  • 3.  RE: ISIS No Route-Through

    Posted 12-01-2022 12:22
      |   view attached
    @STUART RIDSDALE - Unfortunately in my haste, I forgot to fully flesh out the full scenario here.  There are a series of routers behind R1​ that need to use it as a transit.  It just can't be used as a transit for area 100 in this scenario.    I've updated the diagram to show this.

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    CHARLES MAYES
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    Attachment(s)

    pdf
    Drawing1.pdf   45 KB 1 version