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  • 1.  type 1 route in multihomed evpn vxlan

    Posted 05-10-2021 02:54
    hello every one , i tried to make a lab on multihommed evpn vxlan as you see the below topology 

    Configuring the EVPN ESI All-Active Function - CloudEngine 8800, 7800,  6800, and 5800 V200R019C10 Configuration Guide - VXLAN - Huawei

    leaf 1 and leaf 2 are multihommed to VM both have same ESI 01:02:03:04:05:06:07:08:09  as i knew that leaf 1&2 should send route type1 NLRI when i checked on the spine i found  that i received 4 routes type 1  two routes type 1 from leaf1 and two routes type 1 from leaf2 ? 


    root@MX_SPINE> show route receive-protocol bgp 10.10.10.1



    bgp.evpn.0: 6 destinations, 6 routes ( 6 active, 0 holddown, 0 hidden)
    Prefix Nexthop MED Lclpref AS path
    1:10.10.10.1:0::010203040506070809::FFFF:FFFF/192 AD/ESI
    * 10.10.10.1 100 I
    1:10.10.10.1:1::010203040506070809::0/192 AD/EVI
    * 10.10.10.1 100 I
    what is the diffrent between 0 &1 highlighted in the evpn route type 1 ? and why i recivied 2 routes type 1 from leaf1 which i should recive only one route type 1 ? 


    ====================================================================================================
    another question :  as i knew that route type 4 should be propagated between two leafs for DF election my question is why i (SPINE) recieve this route ? 

    4:10.10.10.1:0::010203040506070809:10.10.10.1/296 ES
    * 10.10.10.1 100


  • 2.  RE: type 1 route in multihomed evpn vxlan

     
    Posted 05-10-2021 05:10

    Hi, 

    1:10.10.10.1:0::010203040506070809::FFFF:FFFF/192 AD/ESI
    1:10.10.10.1:1::010203040506070809::0/192 AD/EVI

    There are 2 type-1 routes, 1 for Auto-discovery (AD) per ESI and one for AD per EVI.

    AD per ESI is mandatory for active-active multihoming and used to signal Split-Horizon label and indicate multi-homing mode, used for fast convergence and preventing BUM loops.
    AD per EVI is optional and used to implement aliasing/load-balancing.

    https://www.juniper.net/documentation/us/en/software/junos/evpn-vxlan/topics/concept/evpn-bgp-multihoming-overview.html#jd0e499

    ====================================================================================================
    another question :  as i knew that route type 4 should be propagated between two leafs for DF election my question is why i (SPINE) recieve this route ? 

    I think this depends on the design. If Spines are acting as Route-reflectors, then they are receiving every EVPN routes and reflecting them.

    Cheers,



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



  • 3.  RE: type 1 route in multihomed evpn vxlan
    Best Answer

    Posted 05-11-2021 02:06
    Hi,

    1:10.10.10.1:0::010203040506070809::FFFF:FFFF/192 AD/ESI is RT-1 per ES (ETH TAG ID is set to MAX-ET(all Fs)), described in rfc7432#section-8.2.1, used among other things for fast convergence(when ES link goes down, all MAC routes behind that ES are withdrawn rather than doing it one by one), Junos sets RD to RD:0

    1:10.10.10.1:1::010203040506070809::0/192 AD/EVI is RT-1 per EVI, described in rfc7432#section-8.4.1,  most important function here is aliasing (load-sharing towards all ES members even if only one of them advertised RT-2 with ESI set)

    4:10.10.10.1:0::010203040506070809:10.10.10.1/296 ES - in any BGP VPN all routes are exchanged between all BGP speakers exchanging NLRIs  for a specific AFI/SAFI.
    Specifically to EVPN, since RT (ES-Import Route Target) in RT-4 is derived from ESI, only members of that ES would import it, the rest of BGP EVPN speakers would hold it in EVPN RIB/exchange, but not import.

    Please watch "between 0x2 nerds" YouTube video on the topic
    let me know if anything is unclear

    ------------------------------
    Jeff Tantsura
    ------------------------------



  • 4.  RE: type 1 route in multihomed evpn vxlan

    Posted 05-12-2021 05:00
    could you please clarify  what is the role of Route Label: 1 that exist in  type 1  ESI  and also i see in my lab that every route type 2 have also Route label = vni number