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.  IS-IS protocol L1/L2

    Posted 01-25-2012 12:45

    Hi Expert

     

    As we all know L1/L2 send attached bit toward L1 n Level area for Interarea routing

    Some time it can introduce sub optimal routing .Like if i want to reach destination X the path to X from L1/L2 is more than the my neighbour Level1 router

     

    Isnt   lack feature in IS-IS  that we have to bear Suboptimal routing because only way we can go outside from our area through L1/L2 or is there any work around

     

     

    Your help will be highly appreciated

     

    Thanks



  • 2.  RE: IS-IS protocol L1/L2
    Best Answer

    Posted 01-25-2012 13:20

    Hi Dear

     

    By default the ISIS L1 area is total stub (no inter-area and external routes). L1 ISIS routers rely on default route from L1//L2 router (ASBR). Each L1 ISIS router installs the default route from the nearest L1/L2 router (ASBR). So it could cause the suboptimal routing for the inter-area or external routes. Which is expected behaviour.

     

    You can just do the route leaking for inter-area and external routes from the ASBR if you want to avoid this suboptimal routing.

     

    HTH



  • 3.  RE: IS-IS protocol L1/L2

    Posted 01-25-2012 20:28

    Sorry it was typo ..... I meant ABR not ASBR 🙂