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BGP - multiple ISPs best practise

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  • 1.  BGP - multiple ISPs best practise

    Posted 01-07-2021 03:56

    Hi all.

    I am trying to set up "text book" BGP case for a company with 3 ISPs. Two of them have BGP sessions to both our BGP routers, 3rd have only one peering to our primary router.

    Let's go to worst case scenario. All BGP sessions are down, something went wrong very badly. I can access our BGP routers only via connected IPs to our ISPs, but how should I set default route? I need default route so the traffic from our router know where to go at all.

    How to configure routes on routers, to be able to access routers to any interface IP they have configured?

    For a better understanding a scheme of my setup:

    I hope I described my problem good enough, if not, please ask for additional informations.

    Kind regards

  • 2.  RE: BGP - multiple ISPs best practise
    Best Answer

    Posted 01-07-2021 22:54
    The best option will be OOB network, some small box with 3/4/5G modem and vpn , connected to your internal network , so you can access it any time even all bgp session goes down. 

    One more case: 
    1) you put every link to your ISPs in separate routing-instance, and configure default route in all these tables. 
    2) configure one more routing instance and import all these interface-routes to this ri
    3) configure bgp sessions in ri , configured in (2)
    Crazy case:
    - put evely link to your ISPs in separate ri and configure bgp session
    - import routes from all ri to main ri
    P.S. be carefully with FIB size

    Anatoliy Kushner

  • 3.  RE: BGP - multiple ISPs best practise

    Posted 01-08-2021 04:04

    Thank you for a few solutions, we will look into them and decide what would be the best option for this case.

    Kind regards