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Symmetric and asymmetric mode in VXLAN BGP EPN use case

  • 1.  Symmetric and asymmetric mode in VXLAN BGP EPN use case

    Posted 05-16-2021 20:01
    Hi everybody,
    I am trying to understand use cases for symmetric  and asymmetric mode.

    https://www.juniper.net/documentation/en_US/release-independent/solutions/information-products/pathway-pages/solutions/evpn-type5-configuring.pdf
    From above link:

    By contrast, "symmetric" mode performs an equal number of lookups-IP and MAC-on both the ingress and egress
    NVEs. Symmetric mode is also called the VRF-to-VRF model.

    Advantages of using EVPN Type 5 in DCI
    When a single Layer 2 domain is not extended across multiple data center (DC) locations, the IP subnet belonging to this
    Layer 2 domain is confined within a single DC. If all Layer 2 domains within each DC network satisfy this requirement,
    there is no longer a need to advertise separate MAC+IP routes for each tenant between DCs, as host routes for the
    tenants can be aggregated. Thus, the Layer 2 inter-DC connectivity issue can be simply transformed to an inter-DC Layer
    3 IP prefix reachability issue. A unified EVPN control plane can be used to accomplish Layer 3 route advertisement
    between multiple DC locations, avoiding the need for an additional L3 VPN protocol family.

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    So we can only use asymmetric  mode for inter VNI communication if VLANS are confined  within Data center.

    For example:


    Above we have hosts in v10,v20 at both data center,  in order to provide inter vni communication, we can use  symmetric   mode , we  cannot use symmetric mode because V10,v20 need to be extended between two data centers?

    Thanks and have a good  day!! 








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    zee
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  • 2.  RE: Symmetric and asymmetric mode in VXLAN BGP EPN use case

    Posted 05-24-2021 07:50
    I'm not really sure what your question is - Asymmetric does not use type 5, rather each VTEP must have each VNI configured locally. Symmetric uses type-5 where a transit VNI is used to interconnect VTEPs. Either way, you should be able to route/switch traffic in your scenario.

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    DANIEL HEARTY
    Principal Engineer
    TELENT TECHNOLOGY SERVICES LIMITED
    Southampton
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