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  • 1.  BGP peer preference

    Posted 09-12-2022 14:08
    We've recently added a second BGP peer to our configuration on a MX-5 and want to prefer the first peer's route to the Internet in all cases, unless that peer is unavailable.

    Right now, there is atill a static default route to the first peer, and a higher preference to the 2nd peer has also been added.  However, when the 2nd peer comes up it does start routing traffic to the Internet via that less preferred route.  Shouldn't the static route still supersede everything?

    Beyond that, the second peer ISP said I might need to send them community info to limit what's being accepted by them.  Does that seem correct?  Any advice on how to best and simply configure this dual ISP BGP scenario would be appreciated. Thanks.

    Config (anonymized)

    routing-options {
    static {
    route {
    route next-hop;
    route next-hop;
    autonomous-system 5406x;
    protocols {
    bgp {
    group eBGP {
    type external;
    export adv-bgp;
    neighbor {
    authentication-key "$9$jXim5Fn9u01n6Au1Iyr4oJ"; ## SECRET-DATA
    peer-as 1214x;
    neighbor {
    preference 180;
    peer-as 646x;
    local-as 5406x;


  • 2.  RE: BGP peer preference

    Posted 09-12-2022 16:34
    With your two carriers you need to determine what routes you want to get from them.

    I suspect you need to start by removing the static default routes and have both carriers advertise their default to you.  If you are doing straight primary and failover this may be all you need and just reject the rest of the internet table. 

    The carrier can tell you their advertising options with default, full tables and partial tables.  For straight failover you really just need the default.  The partial and full tables allow you to mix the two carriers if you have the routing memory to hold them and use the best of both for load balancing straight.  Or create more complex policy to prefer some prefixes for particular carriers.

    You would use your import policy to assign the desired preference for the default route.

    For the export of your prefix you will likely need to add the upstream carrier 2 community to decrement the preference so that the route from your primary carrier is the active one unless it goes down.  These communities vary by carrier so you need to get the options list from your sales engineer.

    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)

  • 3.  RE: BGP peer preference

    Posted 09-13-2022 10:54

    Kindly share the outputs of the below commands: -

    a) show route
    b) show route receive-protocol bgp
    c) show route receive-protocol bgp


    Sheetanshu Shekhar