Unknown Mac Route

The Unknown MAC Route (UMR) was first introduced in RFC 7543. It functions as a standard EVPN MAC/IP Advertisement route, with a MAC address length set to 48 bits and the MAC address specified as 00:00:00:00:00:00. UMR was subsequently enhanced in RFC 9014 as a gateway optimization feature.
When multiple data centers (DCs) are interconnected within a single Ethernet Virtual Instance (EVI), each DC must import all MAC addresses from the other DCs. The aggregation of MAC addresses on the control plane can become substantial and may be overwhelmed during mass withdrawals or advertisements. In such scenarios, UMR can be utilized for Provider Edge (PE) devices within the data center to send unknown frames to the DC gateway, which manages the MAC processing with all 0 MAC addresses.
Due to time constraints, our testing was limited to examining the control plane's functionality, with no traffic verification conducted. Initially, we disabled the UMR function on the DC gateway, allowing us to observe multiple MAC addresses on the Virtual Tunnel End Point (VTEP). After enabling UMR on the DC gateway, we confirmed that the MAC addresses on the VTEP, which belonged to the same VXLAN tunnel, were reduced to only one all 0 MAC address.