Hi sachandio,
VPLS has the following shortcomings:
1. Lack of support for load balancing: VPLS does not support traffic load balancing in multi-homing networking scenarios.
2. High network resource usage: Interworking between sites requires all PEs serving these sites on the ISP backbone network to be fully meshed, with PWs established between any two PEs. If a large number of PEs exist, PW establishments will consume a significant amount of network resources. In addition, a large number of ARP messages must be transmitted for MAC address learning. These ARP messages not only consume network bandwidth but may also consume CPU resources on remote sites that do not need to learn the MAC addresses carried in them.
EVPN solves the preceding problems with the following characteristics:
1. EVPN uses extended BGP to implement MAC address learning and advertisement on the control plane instead of on the data plane. This function allows a device to manage MAC addresses in the same way as it manages routes, implementing load balancing between EVPN routes with the same destination MAC address but different next hops.
2. EVPN does not require PEs on the ISP backbone network to fully mesh. PEs on an EVPN use BGP to communicate, and BGP provides the route reflection function. PEs can establish BGP peer relationships only with RRs deployed on the ISP backbone network, with RRs reflecting EVPN routes. This implementation significantly reduces network complexity and minimizes the number of network signaling messages.
3. EVPN enables PEs to use ARP to learn the local MAC addresses and use MAC/IP address advertisement routes to learn remote MAC addresses and IP addresses corresponding to these MAC addresses, and store them locally. After receiving another ARP request, a PE searches the locally cached MAC address and IP address based on the destination IP address in the ARP request. If the corresponding information is found, the PE returns an ARP reply packet. This prevents ARP request packets from being broadcast to other PEs, therefore reducing network resource consumption.
For more information, you can refer to https://support.huawei.com/hedex/hdx.do?docid=EDOC1100109721&id=EN-US_CONCEPT_0172370393&lang=en
I hope it helps!
