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Forum Replies

  1. Hi Rene,
    Thx for your very nice article as always :slight_smile: If there is multiple Level1-2 Router on a area then due to default Route asymmetric Routing will be occurred. I saw your topic about Route leaking but I think its not scalable more . So is there any other scaleble option here ??

  2. Hi @Zaman.rubd,

    Since IS-IS routers only have a default route to get to other areas, sub-optimal routing can be an issue yes. It will depend on your network design. There’s not really an alternative to route leaking as far as I know…somehow you have to get those more specific prefixes in the routing table of your L1 routers.

    For anyone else that is reading this and wondering what this is about, here is an example for IS-IS route leaking and sub-optimal routing:


  3. Hello René,
    Thank you a lot for this lesson. But I don’t see this command circuit-type level anywhere in the course. Normal?

  4. Hello Djan,

    I haven’t added this command indeed. It is pretty straight-forward though, you can use it to tell the router which hello packets to send on the interface: L1, L2 or L1 and L2. You can do this per interface so on Gi0/1 you could send L1 hello packets and on Gi0/2 only L2 hello packets.


  5. Hello Eduardo

    Since the default is-type is level 1-2, then you don’t actually have to explicitly configure the router as a level 1-2 router. This command can indeed be deleted. However, as is the case with many such commands, it’s a good idea to verify that the configuration is correct by implementing the command. This is all the more important when you configure devices that have been previously configured and may have some other configuration already set up.

    I hope this has been helpful!


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