NSX Logical Switching
As mentioned in section 2.1, logical switching in NSX-V is based on the VXLAN protocol while NSX-T is based on the GENEVE protocol. A logical switch is mapped to a unique VXLAN or GENEVE, which encapsulates the virtual machine traffic and carries it over the physical IP network. The NSX logical switch creates logical broadcast domains (devices connected to the same switch) or segments to which an application or virtual machine can be logically wired. This allows for flexibility and speed of deployment while still providing all the characteristics of a physical network's broadcast domains (VLANs).
Both VXLAN and GENEVE protocols help you move to a software-defined data center model. It allows an administrator to provision a virtual machine that can communicate with another virtual machine on a different network without having to configure the physical switches and routers.
You may remember from the section. 2.4 that VXLAN has several advantages over VLAN:
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VLAN networks can't be saved, snapshotted, cloned, deleted, or moved, which could negatively impact business continuity in the event of a system failure;
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every time a VLAN is extended, a time-consuming physical configuration is needed; by contrast, because VXLAN uses overlay technology, with virtual Layer 2 network is abstracted from the underlying physical network and can be configured and reconfigured very quickly.
What’s more, you can use VXLAN logical switches (which are Layer 2 Ethernet broadcast domains) to cross Layer 3 network boundaries. This allows for virtual machine mobility within the data center (with vMotion) without limitations of the physical Layer 2 (VLAN) boundary.
As discussed in section 2.4, the original Ethernet frame generated by a workload is encapsulated with external VXLAN, UDP, IP, and Ethernet headers to ensure it can be transported across the network infrastructure interconnecting the ESXi hosts.
Each logical switch is relegated a Unique VXLAN numerical identifier. Each logical switch is made as a port gathering on the appropriated switch. Sensible switches can stretch out over various appropriated switches.
VXLAN runs over standard switching hardware and has been embraced by more vendors.
The logical switching capability in the NSX-T platform provides the ability to create isolated logical L2 networks with the same flexibility and agility that exists for virtual machines.
