Protocol Independent Multicast (PIM) is used to ensure that all switches for the multicast groups can advertise their existence and learn about other VTEPs in a VXLAN environment. PIM is designed to efficiently route multicast packets, making it the right protocol for managing multicast traffic in VXLAN.
Layer 2 data must be encapsulated when traversing an IP network because the IP network operates at Layer 3, which does not natively support Layer 2 frames. Encapsulation methods like VXLAN, GRE, or MPLS allow these Layer 2 frames to be transmitted over a Layer 3 IP network. This encapsulation is necessary to maintain the integrity and delivery of Layer 2 data between data centers.
In a data center environment where VMs and hosts are frequently moved, technologies that provide efficient traffic management and minimize unnecessary data paths are crucial. VXLAN (Virtual Extensible LAN) helps in creating a scalable network architecture, enabling layer 2 segments to span multiple locations over a layer 3 network. EVPN (Ethernet VPN) provides advanced control over the VXLAN gateway for improved routing efficiency and mobility. Together, VXLAN and EVPN enable efficient traffic flows and seamless VM mobility, making them a suitable solution for the scenario described.
MPLS EVPN interconnects provide several advantages. They allow for local proxy ARP/ND resolution, which can reduce the amount of broadcast traffic and improve performance and security. They enable point-to-multipoint connectivity, facilitating multipoint connections and enhancing network scalability and efficiency. They support MAC learning in the control plane, which offers better scaling and security by preventing flooding of unknown unicast traffic.