Comprehensive and Detailed 250 to 350 words of Explanation From VMware Cloud Foundation (VCF) documents:
In the context ofVMware Cloud Foundation (VCF)networking, understanding how an ESXi host (acting as a Transport Node) handles East-West traffic is fundamental. East-West traffic refers to communication between workloads within the same data center, often on the same logical segment.
When a Virtual Machine sends a frame to another VM on the same logical segment, the ESXi host's virtual switch must determine the "location" of the destination MAC address to performframe forwarding. TheMAC Table(also known as the Forwarding Table or L2 Table) is the primary structure used for this decision. For each logical segment, the host maintains a MAC table that maps the MAC addresses of virtual machines to their specific "locations."
If the destination VM is residing on thesame host, the MAC table points the frame toward a specific internal port (vUUID) associated with that VM's vNIC. If the destination VM is on adifferent host(in an overlay environment), the MAC table entry for that remote MAC address will point to theTunnel End Point (TEP)IP of the remote ESXi host. While the TEP table (Option C) contains the list of known Tunnel Endpoints and the ARP table (Option A) maps IP addresses to MAC addresses, neither is the primary table used for the finalframe forwardingdecision.
TheMAC Tableis the authoritative source for Layer 2 forwarding. In an NSX-managed VCF environment, these tables are dynamically populated and synchronized via theLocal Control Plane (LCP), which receives updates from the Central Control Plane. This ensures that even as VMs move via vMotion, the MAC table remains updated across all transport nodes, allowing for seamless East-West connectivity without the need for traditional MAC learning (flooding) in the physical fabric.
