You can prepare a vSphere cluster to support VXLAN.
Host preparation:
• NSX Manager pushes the hypervisor kernel modules to the cluster’s ESXi hosts: The hypervisor kernel modules enable ESXi hosts to support VXLAN, the logical switch, the distributed router, and the distributed firewall.
• Create the VXLAN vmknic interfaces to be used as VTEP interfaces: – VMware recommends that you use a MTU size of at least 1600 to allow for the VXLAN overhead of 50 bytes.
• When you configure VXLAN networking, you must provide a vSphere Distributed Switch, a VLAN ID, an MTU size, an IP addressing mechanism (DHCP or IP pool), and a NIC teaming policy.
Logical network preparation:
• Create the VNI pool.
• Specify multicast IP ranges for hybrid and multicast replication modes. The recommended multicast range starts at 239.0.1.0/24 and excludes 239.128.0.0/24
• The transport zone defines the members or VTEPs of the VXLAN overlay:
i). The transport zone can include ESXi hosts from different vSphere clusters.
ii). A cluster can be part of multiple transport zones.
Physical Network requriements:
Multicast Support is required from the physical network in case Hybrid or Multicast replication modes are leveraged for logical switches.
The recommended multicast range starts at 239.0.1.0/24 and excludes 239.128.0.0/24.
The use of 239.0.0.0/24 or 239.128.0.0/24 is not recommended, because these networks are used for local subnet control. This means that the physical switches flood all the traffic that uses these addresses.
Several modes of traffic replication exist:
• Unicast and hybrid are based on VMware NSX Controller: – Unicast mode is all replication using unicast.
• Hybrid mode is local replication that is offloaded to the physical network and remote replication through unicast.
• Multicast mode requires Internet Group Management Protocol (IGMP) for a layer 2 topology and multicast routing for layer 3 topology.
VMware NSX Logical Routing
When sending traffic to a remote segment, the sending VTEP elects a proxy VTEP in the destination segment. The proxy VTEP selection is made locally and independently by each ESXi host to ensure that replication duties can be shared by multiple VTEPs. • In unicast mode, the proxy VTEP is called a Unicast Tunnel End Point (UTEP). • In hybrid mode, the proxy VTEP is called a Multicast Tunnel End Point (MTEP).
Overview of Encapsulation and Decapsulation with VXLAN
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