NSX-T Flashcards
What is a virtual switch?
a piece of software that emulates a physical Layer 2 networking device; allows to interconnect virtual machines in the same fashion as physical devices
How does a virtual switch provide physical network connectivity?
by mapping uplink ports to the physical network interface cards (NICs) of the host
What does it mean that VMware vSphere implements a single-tier virtual switch network topology?
there is no way to directly interconnect multiple virtual switches
What are the two virtual switches supported by vSphere?
- vSphere Standard Switch (VSS)
- vSphere Distributed Switch (VDS)
What is VSS?
localized, resides within a single host
What is vSphere Distributed Switch (VDS)?
more robust capabilities that span across multiple hypervisor hosts
How does VSS implement data plane and management plane?
- contains both management and data planes in a single package
- must configure and maintain each vSS instance individually
What defines how virtual machine connections are made through the vSS to the physical network?
a port group
What if a port group has no physical NICs configured?
virtual machines can only communicate with each other but do not have connectivity to the external network
How does VDS behave?
like a single switch across all associated hypervisor hosts in a data center
How does VDS implement data plane and management plane?
- has separate management and data planes
- vCenter provides the management-plane functionality, and the data plane remains local to each hypervisor host via a host proxy switch that is associated to the vDS
In which environments is VDS most useful?
environments that use advanced features like vMotion because a virtual machine is able to access its assigned distributed port group on each hypervisor host associated to the VDS
What are the supported NIC load balancing mechanisms?
- Route Based on Originating Virtual Port
- Route Based on IP Hash
- Route Based on Physical NIC Load
How does Route Based on Originating Virtual Port load balancing mechanism work?
- selects an uplink based on the virtual machine port ID
- no specific upstream switch configurations needed
- virtual guest throughput is limited to the speed of the selected uplink
How does Route Based on IP Hash load balancing mechanism work?
- selects an uplink based on the source and destination IP address of each packet
- requires the physical switches to be configured with active or passive Etherchannel
- virtual guest flows are load-shared across all associated uplinks
How does Route Based on Physical NIC Load load balancing mechanism work?
- starts using the default route based on originating virtual port
- moves to a virtual port when an uplink port reaches 75% utilization over a 30 sec period
- no specific upstream switch configurations needed
- requires vSphere Enterprise Plus
What is the defaul load balancing mechanism?
Route Based on Originating Virtual Port
What are the different vNICs that vSphere support?
- E1000 and E1000E
- VMXNET3
Describe E1000 and E1000E
- virtual Ethernet adapters that emulate Intel 82545EM or 82574 network adapters
- require additional CPU cycles to process all guest virtual-machine network traffic
Describe VMXNET3
- a para-virtualized device created by VMware
- no emulated hardware - optimized for performance
- functions like a 10G NIC
How does Single Root I/O Virtualization (SR-IOV) work?
- enables a device, such as a network adapter, to appear as multiple independent physical devices to the hypervisor or the guest virtual machine’s operating system
- exchanges data directly with the physical adapter, bypassing the VMkernel
Which environment does Single Root I/O Virtualization (SR-IOV) fit the best?
workloads with very high packet rates or low latency requirements
What are the compatibility constraints of Single Root I/O Virtualization (SR-IOV)?
not compatible with several vSphere virtualization features such as vMotion, HA, and DRS
What are the methods of using VLAN tagging in vSphere?
- external switch tagging (EST)
- virtual switch tagging (VST)
- virtual guest tagging (VGT)
