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  • 1.  Default route

    Posted 06-09-2023 12:10

    Hello,

    I would like to advertise a default route from Juniper MX to Cisco N7k in BGP in VPN x. Currently, the VPN does not have a default route. I don't want Juniper's VPN routing table to contain a default route, just to advertise it.

    I have the config to advertise the route, but since there is no default route in the VPN routing table, nothing gets advertised.

    Do you know how to fix it?

    Thanks

    Petr



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    Petr Nemg
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  • 2.  RE: Default route

    Posted 06-10-2023 07:52

    A route has to exist for BGP to advertise it to a neighbor.

    You could create a static discard route for this purpose so it would not be used to forward traffic 

    set routing-options static route 0.0.0.0/0 discard

    This could also be inside a routing instance if that is how your vpn is setup.

    set routing-instance VPN_instance routing-options static route 0.0.0.0/0 discard 



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

    Posted 06-11-2023 09:47
    Edited by Olivier Benghozi 06-11-2023 09:47

    Actually you can advertise a non-existing route with BGP using bgp-static:

    https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-session-flaps.html#id-understanding-bgp-static-routes-for-preventing-route-flaps

    But that's usually not a good idea, usually you want to create a (real) static route.



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    Olivier Benghozi
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  • 4.  RE: Default route

    Posted 06-12-2023 05:43

    Thank you,
    I will use your solution. 
    I have one additional question. Should I do this on all routers within the VPN or just two?
    The VPN have many sites. Each site has two routers. I need to pass the traffic to a different network.



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    Petr Nemg
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  • 5.  RE: Default route

    Posted 06-12-2023 05:48

    The static discard routes would need to be created on any routing instance what need to originate the default route to a neighbor.

    For example, if you have a typical hub and spoke it would be the two routers at the hub site distributing this to all the remote ones.



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



  • 6.  RE: Default route

    Posted 06-12-2023 07:34

    Thank you. It worked.



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    Petr Nemg
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