Table 1: Scenario 1: Broadcast, Unkown Unicast, Multicast traffic Forwarding BUM traffic is forwarded by a VTEP into the VXLAN Core using multicast routing. In order to follow the path of an ARP broadcast packet, you need to identify the multicast group that needs to be used to send this traffic into the core and to the other VTEPs. BUM traffic first arrives at the local Layer 2 interface. The traffic is encapsulated here and sent out using the multicast group that is sourced from the VXLAN Loopback interface. Underlay multicast needs to be fully configured before troubleshooting BUM traffic forwarding for EVPN VXLAN.
Note To troubleshoot EVPN VXLAN BUM traffic forwarding, follow these steps: 1. Determine the MAC Address of the Local Host Device and the Multicast Group Used for ARP Tunneling, on page 3 2. Set Up Embedded Capture Towards the Core-Facing Interface, on page 4 3. Ping the Remote Host Device, on page 4 4. Verify that an ARP Request Has Been Received and a Multicast Route Has Been Built, on page 4 5. Confirm the Presence of ARP Request Replies in Embedded Capture, on page 5 6. Verify that the Encapsulated ARP Request is Leaving in a Multicast Group to a VXLAN UDP Destination Port, on page 5 7.
Verify that the ARP Reply from Core Interface is Encapsulated in Unicast to a VXLAN UDP Destination Port, on page 6 Determine the MAC Address of the Local Host Device and the Multicast Group Used for ARP Tunneling The following examples show how to verify the MAC address of the local host device and the multicast group that is used for tunneling the ARP broadcast request: Troubleshooting BGP EVPN VXLAN Troubleshooting Broadcast, Unkown Unicast, Multicast Traffic Forwarding Check to be Performed Steps to Follow Is the packet of broadcast type? Check if the packet is a broadcast packet, such as an ARP broadcast packet. Are the hosts in the same subnet or in different subnets?
Perform any of the following steps: • Check the host device. • Check the SVI configuration on the VTEP. Has the remote MAC address been learned for unknown unicast traffic? Run the show platform software fed switch active matm macTable vlan vlan-id command in privileged EXEC mode on the local VTEP and check if the MAC address of the remote host device is displaed in the output. If not, you have not yet learned the remote host device and it needs to be resolved. Troubleshooting BGP EVPN VXLAN 3