Routing

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Type 2 EVPN Routes

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  • 1.  Type 2 EVPN Routes

     
    Posted 04-29-2021 12:18

    Hi.

     

    Can someone please let me know why an EVPN PE advertises two Type 2 routes for one MAC address – one with an accompanying IP address and one without?

     

    {master:0}[edit]

    lab@leaf1# run show route advertising-protocol bgp 192.168.100.1 match-prefix 2*   

     

    default-switch.evpn.0: 8 destinations, 12 routes (8 active, 0 holddown, 0 hidden)

      Prefix                   Nexthop        MED         Lclpref    AS path

      2:192.168.100.11:1::5010::52:54:00:5e:88:6a/304 MAC/IP           

    *                         Self                         100        I

      2:192.168.100.11:1::5010::52:54:00:5e:88:6a::10.1.1.1/304 MAC/IP           

    *                         Self                         100        I

     

    The Type 2 route that contains just the advertised MAC address seems unnecessary.

     

     

    Thanks,

    Deepak


    Juniper Business Use Only



  • 2.  RE: Type 2 EVPN Routes
    Best Answer

     
    Posted 09-09-2021 05:39

    Hi, 

    I believe this is as per RFC7432:

    Note that a MAC-only route can be advertised along with, but
       independent from, a MAC/IP route for scenarios where the MAC learning
       over an access network/node is done in the data plane and independent
       from ARP snooping that generates a MAC/IP route.  In such scenarios,
       when the ARP entry times out and causes the MAC/IP to be withdrawn,
       then the MAC information will not be lost.  In scenarios where the
       host MAC/IP is learned via the management or control plane, then the
       sender PE may only generate and advertise the MAC/IP route.  If the
       receiving PE receives both the MAC-only route and the MAC/IP route,
       then when it receives a withdraw message for the MAC/IP route, it
       MUST delete the corresponding entry from the ARP table but not the
       MAC entry from the MAC-VRF table, unless it receives a withdraw
       message for the MAC-only route.



    ------------------------------
    Ashvin
    ------------------------------



  • 3.  RE: Type 2 EVPN Routes

     
    Posted 09-09-2021 09:55
    Thanks Ashvin for your answer. I was able to verify this in the lab.

    Cheers,
    Deepak