Configuring EVPN to Advertise UMR Routes

Configuring EVPN to advertise unknown MAC routes (UMRs) helps mitigate the MAC address learning pressure of RRs and aggregation devices.

Context

In the standard EVPN VPLS networking solution, all user-side specific MAC routes are transmitted through an RR on the entire network. As a result, the RR has heavy MAC address learning pressure. In addition, an aggregation device usually connects to multiple access devices. Therefore, aggregation devices also have heavy MAC address learning pressure, and the MAC address table capacity of aggregation devices limits the number of access users.

To solve this problem, configure EVPN to advertise UMRs. On the network shown in Figure 1, configure each ALeaf node at the access layer to generate and advertise a UMR to the RR, but not to advertise specific MAC routes to the RR. This can reduce the MAC address learning pressure of the RR. Meanwhile, configure the RR to reflect only the UMRs sent by ALeaf nodes to the SLeaf node at the aggregation layer. This can reduce the MAC address learning pressure of the SLeaf node and prevent the MAC address table capacity of the SLeaf node from limiting the number of access users. Moreover, you need to configure ALeaf nodes to send only specific MAC routes to each other and configure the RR to reflect only received specific MAC routes to ALeaf nodes, so that EVPN VPLS services can run properly.

Figure 1 UMR advertisement through EVPN

Pre-configuration Tasks

Before configuring EVPN to advertise UMRs, complete one of the following tasks:

Procedure

Enable UMR generation on each ALeaf node.
1. Run system-view
  The system view is displayed.
2. Run bridge-domain bd-id
  The view of the BD bound to the EVPN instance is displayed.
3. Run umr originate [ detail-suppressed ]
  UMR generation is enabled.
  
  If detail-suppressed is not specified in this step, UMRs are generated, but specific MAC routes are not suppressed. In other words, both UMRs and specific MAC routes can be advertised. If detail-suppressed is specified, UMRs are generated, and specific MAC routes are suppressed. In other words, only UMRs can be advertised in this case.
  
  In the current scenario, the umr originate detail-suppressed command needs to be run on each ALeaf node to generate UMRs and suppress specific MAC routes.
4. Run commit
  The configuration is committed.
5. Run quit
  Return to the system view.
Configure an ALeaf node to advertise only specific MAC routes to other ALeaf nodes.
1. Run bgp { as-number-plain | as-number-dot }
  The BGP view is displayed.
2. Run l2vpn-family evpn
  The BGP EVPN address family view is displayed.
3. Run peer { peerIpv4Addr | peerIpv6Addr | groupName } advertise evpn mac-route detail-only
  The device is configured to advertise only specific MAC routes to a specified peer or peer group.
  
  Because ALeaf nodes only need to exchange specific MAC routes with each other and do not need to exchange UMRs, the peers or peer groups specified in this step refer to other ALeaf nodes. After this step is performed, ALeaf nodes advertise only UMRs to the RR and advertise specific MAC routes to other ALeaf nodes.
4. Run commit
  The configuration is committed.
Configure the RR to advertise only specific MAC routes to ALeaf nodes.
1. Run system-view
  The system view is displayed.
2. Run bgp { as-number-plain | as-number-dot }
  The BGP view is displayed.
3. Run l2vpn-family evpn
  The BGP EVPN address family view is displayed.
4. Run peer { peerIpv4Addr | peerIpv6Addr | groupName } advertise evpn mac-route detail-only
  The device is configured to advertise only specific MAC routes to a specified peer or peer group.
  
  Because ALeaf nodes only need to learn specific MAC routes and do not need to learn UMRs, the peers or peer groups specified in this step refer to other ALeaf nodes. After this step is performed, the RR reflects only UMRs to the SLeaf node and reflects only specific MAC routes to ALeaf nodes.
5. Run commit
  The configuration is committed.
Enable UMR forwarding on the SLeaf node.
1. Run system-view
  The system view is displayed.
2. Run bridge-domain bd-id
  The view of the BD bound to the EVPN instance is displayed.
3. Run umr forward enable
  UMR forwarding is enabled.
  
  After this step is performed, the SLeaf node forwards received unknown unicast packets based on UMRs first. If no matching UMR is found, the SLeaf node forwards these packets as BUM packets.
4. Run commit
  The configuration is committed.

Verifying the Configuration

After completing the configuration, perform the following operations to verify it:

Run the display bgp evpn all routing-table mac-route 0:48:0000-0000-0000:0:0.0.0.0 command on an ALeaf node to check the advertised UMR or on the SLeaf node to check the received UMR.
If specific MAC route suppression is specified when UMR generation is enabled on an ALeaf node, you can run the display bgp evpn all routing-table mac-route prefix command on the ALeaf node to view a specified specific MAC route. The command output shows that the route is marked with the suppressed flag.