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EVPN-VXLAN Pure Type 5 Host-Route Auto-Generated Community

Border leaf devices in edge-routed bridging (ERB) EVPN topologies with Type 5 connectivity to external EVPN networks need to advertise aggregate routes to the external networks instead of individual Type 5 host routes. Leaf devices configured with the auto-generated community add a community to MAC-IP ARP/NDP based Type 5 routes and Type 2 MAC-IP routes. When the remote PE generates a Type 5 route from the received Type 2 route, it inherits the community. Border leaf devices can use this community to identify these routes and create an aggregate route to advertise to external EVPN networks.

Benefits

  • Provides a mechanism to automatically add a community to locally learned MAC-IP ARP/NDP based pure Type 5 host routes and Type 2 MAC-IP routes.

Behavior and Limitations

Note the following runtime behaviors and limitations with this feature:

  • This feature applies to the EVPN locally learned host routes within a Layer 2 instance. The policy only needs a single action to add a community. It is not required to match anything in the route. But you can add a matching qualifier [route-filter, route-filter-list, prefix-filter, prefix-filter-list] to the policy to limit which routes are matched, if necessary.

  • The IP host route inherits the community from the remotely learned Type 2 MAC-IP route when added to the L3VRF.inet or inet6.0 table. The Type 5 IP prefix routes generated from those Type 2 routes also inherit that community. However, you can prevent that inheritance by configuring the export-action skip option under [routing-instances name protocols evpn ip-prefix-routes route-attributes community].

  • The export policy does not modify any other route parameters. It only adds a community to the locally learned EVPN host routes.

  • The export policy does not add a community to Type 2 MAC-IP routes generated for IRB physical or virtual gateway IP Addresses.

  • Applying this policy to an EVPN Layer 2 instance does not change the existing behavior for advertising or receiving Type 5 routes.

  • An ip-prefix-route export policy configured to delete or override communities on IP Host Routes in the VRF instance while generating EVPN Type 5 routes will also drop the community that is added to the IP Host Route by the export policy under EVPN Layer 2 instance.

  • The export policy does not reject learning of any local host routes in EVPN.

  • The export policy does not reject advertising Type 2 MAC-IP routes. Existing VRF export policies under the EVPN instance or under [protocols bgp] continue to be used to reject advertising Type 2 MAC-IP routes.

  • The export policy does not reject a locally learned EVPN route from being added to L3VRF.inet or inet6.0 table and therefore does not prevent generating a T-5 route for locally learned host routes. The existing export policies under [ip-prefix-route export] or [protocols bgp] are used to reject advertising Type 5 routes.

Configure Type 5 Host-Route Auto-Generated Community

You enable the Type 5 Host-Route Auto-Generated Community by configuring the mark-local-ip-host-routes statement under the EVPN Layer 2 Instance. The statement invokes a policy that adds a community to the EVPN locally learned host routes for that instance.

  1. Enable the auto-generated community in the routing instance.

  2. Configure the community to identify the routes.

  3. Configure the policy to add the community to the routes.

    1. Add the community without any filters.

    2. Add the community using a matching qualifier [route-filter, route-filter-list, prefix-filter, prefix-filter-list].

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