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"strict" option of "install-nexthop lsp" command turns my routes "Unusable"

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  • 1.  "strict" option of "install-nexthop lsp" command turns my routes "Unusable"

    Posted 07-03-2018 05:53

    Hello team:

    I have two RSVP LSPs built on my PE to reach a remote PE´s loopback address (iBGP environment).

     

    I want the worst (in metric terms) of these LSPs to forward traffic to specific VRF routes announced by the remote PE (the ones that the remote PE announce with a specific BGP community)

     

    For this purpose I was told to use the "routing-options forwarding-table export <policy>" command, calling the router to use a specific LSP if the community matches what I want.

     

    I have not had success:

    • if I call the install-nexthop command without the "strict" option, then the router just ignores me and keeps using the LSP with best metric to the destination PE
    • if I call the install-nexthop with the "strict" option, the router changes the VRF destination routes to "hidden" (Next hop type: Unusable)
    • if I temporarily deactivate the "best LSP", now the router does install the destination VRF routes using the remaining LSP, regardless of whether I use the "strict" option or not. This is what I would like to happen, but at the expense of having to erase one LSP.

    ¿ Anything I am missing to make this work?

    Any hints will be greatly appreciated.

    Best regards

     

    Rogelio Alvez

    Argentina

     

     

     



  • 2.  RE: "strict" option of "install-nexthop lsp" command turns my routes "Unusable"
    Best Answer

    Posted 07-03-2018 06:16

    Hello,

    The "install-nexthop lsp" feature is supposed to be used with equal-cost LSPs.

    By default, all LSPs towards the same destination irrespective of the actual path taken share the same cost equal to minimum IGP cost.

    So, if You are costing out one of the LSPs then "install-nexthop lsp" feature is not expected to work. And what You are observing in Your tests is expected.

    You'd need to keep the same metric/cost for all LSPs towards the same destination and then apply "install-nexthop lsp" policy.

    HTH

    Thx

    Alex



  • 3.  RE: "strict" option of "install-nexthop lsp" command turns my routes "Unusable"

    Posted 07-03-2018 06:40

    Matching the metrics on both LSPs made the magic! Smiley Happy

     

    You saved my day! 🐵

     

    Thanks a lot!!!! Rogelio