The abstraction by using a VXLAN-like overlay does not inherently change the Flood & Learn behavior introduced by Ethernet. IETF RFC7348 – VXLAN: A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks Isolation of Broadcast and Failure Domains.Scalability, convergence, and resiliency of a Layer-3 network.Layer-3 routing with Equal Cost Multi-Path (ECMP) allows all available links to be used.No dependency on Spanning-Tree protocol by leveraging Layer-3 routing protocols.However, significant improvements in the following areas have been achieved: While the VXLAN VNI allows unique identification of a large number of tenant segments which is especially useful in high-scale multi-tenant deployments, the problems and requirements of large Layer-2 Domains are not sufficiently addressed. By encapsulating the original Ethernet frame with a VXLAN header, the newly introduced addressing field offers 24-bits, thereby providing a much larger namespace with up to 16 Million Virtual Network Identifiers (VNIs) or segments.
Chief among the advantages provided by VXLAN extension of the todays limited VLAN space and the increase in the scalability provided for Layer-2 Domains.Įxtended Namespace – The available VLAN space from the IEEE 802.1Q encapsulation perspective is limited to a 12-bit field, which provides 4096 VLANs or segments. By introducing an abstraction through encapsulation, VXLAN has become the de-facto standard overlay of choice in the industry. VXLAN (IETF RFC7348) has been designed to solve specific problems faced with Classical Ethernet for a few decades now. Given the tremendous interest in VXLAN with MP-BGP based EVPN Control-Plane (short EVPN) at Cisco Live in Milan, I decided to write a “short” technology brief blog post on this topic.