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vrf-import

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  • 1.  vrf-import

    Posted 12-07-2019 01:59

    Hi,

    I am getting myself confused over the use of both the VRF commands vrf-import and vrf-export with a policy and that is matching a community target (import). I see all routes in the bgp.l3vn.0 table but it is what gets into or not into the VRF table and how the vrf-import or vrf-export policy influences that as opposed to an edge eBGP peering config with no policies.

    With the configuration below will eBGP routes be imported to the VRF table with a community that does not match the policy, because when I have this in the lab eBGP routes from the CE that do not match the community value in the vrf-import policy get imported from the bgp.l3vpn.0 table to the TEST1 VRF table ?

     

    user@MXrouter> show configuration routing-instances TEST1
    instance-type vrf;
    interface xe-1/0/0.0; #edge eBGP peering
    route-distinguisher 64512:00000;
    vrf-import POLICY1_IMPORT;
    vrf-export POLICY1_EXPORT;
    vrf-table-label;
    autonomous-system 64512;
    }
    protocols {
    bgp {
    group CE_ROUTER {
    type external;
    local-address 10.1.1.1;
    peer-as 65534;
    neighbor 10.1.1.2; #edge eBGP peering
    }
    }
    }
    {master}
    user@MXrouter>show configuration policy-options policy-statement POLICY1_IMPORT
    term IMPORT {
    from {
    protocol bgp;
    community ROUTES_IN_RT;
    }
    then accept;
    }
    term REJECT_ALL {
    then reject;
    }
    set policy-options community ROUTES_IN_RT members target:65534:11110001
    }
    user@MXrouter>show route 10.100.200.0 detail receive-protocol bgp 10.1.1.2 table TEST1.inet

    RMG_GCP_ICE.inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)
    * 10.100.200.0 (1 entry, 1 announced)
    Accepted
    Nexthop: 10.1.1.2
    AS path: 65534 ?
    Communities: target:65535:11110002 target:65536:11110003

    {master}
    user@MXrouter>

    I thought this route should have been rejected as the community values dont match ?

     



  • 2.  RE: vrf-import

    Posted 12-07-2019 02:50

    Hello,

    "vrf-import" policy does NOT affect routes received on PE-CE BGP sessions. If You want to filter routes received from CE, You need to put an import policy under CE neighbor/group level. 

    In case of MPLS L3vpn, "vrf-import" only affects the routes on the way from bgp.l3vpn.0 table to <vrfname>.inet.0 table, and only in that direction.

    HTH

    Thx

    Alex



  • 3.  RE: vrf-import

    Posted 12-07-2019 14:22

    Thanks Alex, thats good explaination, but where my understanding gets confused is why I see the PE-CE remote route in the bgp.l3vpn table, apologies if I'm not seeing the obvious here:

     

    user@MXrouter> show route table bgp.l3vpn.0 protocol bgp

    bgp.l3vpn.0: 44 destinations, 54 routes (44 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both

    64512:10190:10.100.200.0/29
    *[BGP/170] 5w1d 00:46:50, localpref 100
    AS path: 65534 I, validation-state: unverified
    > to 10.1.1.2 via xe-1/0/0.0

    user@MXrouter> show route table bgp.l3vpn.0 10.100.200.0/29 detail

    bgp.l3vpn.0: 44 destinations, 54 routes (44 active, 0 holddown, 0 hidden)
    64512:10000:10.100.200.0/29 (1 entry, 1 announced)
    *BGP Preference: 170/-101
    Next hop type: Router, Next hop index: 765
    Address: 0x~~~~~~~
    Next-hop reference count: 30
    Source: 10.1.1.1
    Next hop: 10.1.1.2 via xe-1/0/0.0, selected
    Session Id: 0x###
    State: <Secondary Active Ext>
    Local AS: 64512 Peer AS: 65534
    Age: 1w5d 16:46:00
    Validation State: unverified
    Task: BGP_65534_64512.10.1.1.2
    Announcement bits (1): 1-BGP_RT_Background
    AS path: 65534 ?
    Communities: target:65535:11110002 target:65536:11110003
    Accepted
    Localpref: 100
    Router ID: x.x.x.x
    Primary Routing Table TEST1.inet.0



  • 4.  RE: vrf-import
    Best Answer

    Posted 12-07-2019 20:07

    Hello,

     


    @colin1000 wrote:

    why I see the PE-CE remote route in the bgp.l3vpn table,


     

    That's "vrf-export" policy which gets a route received from CE into bgp.l3vpn.0 table.

    One more time:

    - "vrf-import" : works for bgp.l3vpn.0 -> <vrfname>.inet.0 

    - "vrf-export" : works for <vrfname>.inet.0 -> bgp.l3vpn.0

    - PE-side BGP CE-neighbor import policy: works for CE->PE BGP RIB-In -> <vrfname>.inet.0

    Hope this makes sense.

    HTH

    Thx

    Alex



  • 5.  RE: vrf-import

    Posted 12-07-2019 23:53

    Hi Alex,

    The penny drops, your time to repond is much appreciated 🙂