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  • 1.  Question on selective route reflection

     
    Posted 11-28-2023 08:13

    Hi.

    I have an MX route reflector that is receiving both L3VPN and IPv4 routes from a client. How do I configure the route reflector to only reflect the L3VPN routes and not the inet.0 routes? Is there a way to do this without configuring multiple IP addresses on loopbacks?

    Thanks,

    Deepak



  • 2.  RE: Question on selective route reflection

    Posted 11-29-2023 10:29

    Hi Deepak,

    Just a quick question from my side, do I understand your question correctly?

    You have a client, lets call it R1, who sends both IPv4 unicast and IPv4 L3VPN routes to a route reflector. And this route reflector should only readvertise the IPv4 L3VPN routes to other clients and not the IPv4 unicast routes?



    ------------------------------
    Johannes |
    A computer's attention span is only as long as its power cord.
    ------------------------------



  • 3.  RE: Question on selective route reflection

     
    Posted 12-13-2023 00:46

    Hi Johannes.

    Thanks for looking into this.

    Your understanding of the question is correct. 

    One detail I forgot to mention is that both clients advertise both unicast and VPN routes to the reflector. Yet I would like only the VPN routes to be reflected by the route reflector to the 'other' client.

    Regards,

    Deepak




  • 4.  RE: Question on selective route reflection

    Posted 12-13-2023 02:53

    Hi Deepak,

    So I tested a solution in the lab which should work quite nicely.

    What you need to do is the following:

    1. You create an import policy for the targeted client (R1 as of my last post), which marks any inet-vpn routes with a special community you create. I called mine "no-readvertise" and applied it to the BGP config on the RR. Here ist the config:

    ### Policy Options
    policy-statement peer-marking {
        from family inet-vpn;
        then {
            community add no-readvertise;
        }
    }
    community no-readvertise members target:65000:999;
    
    ### BGP Config (this is again your client, from which you only want to redistribute inet routes)
    neighbor 172.16.0.1 {
         import peer-marking;
    }

    2. After creating and applying the previous policy (or expanding an existing one, if you already have a specific policy for that router), you create an export policy, which will reject all routes with your special community (again, in my case it's "no-readvertise", but name it however you like) and accept all other routes. Then apply it as an export policy on your RR:

    ### Policy Options
    policy-statement no-readvertise {
        term deny {
            from community no-readvertise;
            then reject;
        }
        term else {
            then accept;
        }
    }
    
    ### BGP
    export no-readvertise;

    Policies are the simplest and easiest way to control your BGP route flow in your network. Please always check that new policies do not interfere with your existing ones. If you need any more help, just ask me.

    BR, Johannes



    ------------------------------
    Johannes | Systems Engineer
    A computer's attention span is only as long as its power cord.
    ------------------------------



  • 5.  RE: Question on selective route reflection

    Posted 12-14-2023 06:02

    Apart from what Johannes suggested - if you don't need IPv4 routes from that client anywhere, you can also configure the BGP session to that RR client to exchange only VPNv4 routes. Per-neighbor AFI/SAFI configuration will override per-group or global configuration:

    protocols {
        bgp {
            group RR_CLIENTS {
                family inet unicast;
                family inet-vpn unicast;
                neighbor 198.51.100.1 {
                    family inet-vpn unicast;
                }
            }
        }
    }


    ------------------------------
    Berislav Todorovic
    ------------------------------