Lesson 10
Legacy network adapters
(previously known as emulated network adapters) are only available in Generation 1 virtual machines. Legacy adapters communicate by making calls to the hypervisor. They emulate an Intel 21140‐based PCI Fast Ethernet Adapter and can be used to boot to a network so you can install an operating system from a service such as Windows Deployment Services.
Which virtual switch types does not enable guest OSs to communicate with the parent partition?
Private
Static MAC address
By default, virtual network adapters receive a dynamically assigned MAC address from the Hyper‐V server; you can also create a static MAC address, by using this option. The only requirement is that no other adapter, virtual or physical, on the same network uses the same address.
How many virtual adapters can a virtual machine support?
Each virtual machine can support a total of 12 virtual network adapters (8 Hyper‐V synthetic adapters and 4 legacy network adapters).
Media Access Control (MAC) address
The MAC address is a 6‐byte hexadecimal value—the first 3 bytes are an organizationally unique identifier (OUI) that specifies the manufacturer, and the last 3 bytes identify the adapter itself.
Virtual machine queue (VMQ)
uses hardware packet filtering to deliver data directly to virtual machines from an external network, reducing the overhead of routing packets from the management operating system to the virtual machine. Only Hyper‐V‐specific network adapters support this feature.
How do you prevent address duplication?
you change the second‐to‐last byte only, by making it into a range of addresses like the last byte.
The first 3 bytes of the MAC address range are always?
The first 3 bytes of the MAC address range are always 00‐15‐5D, which is an OUI registered by Microsoft.
The fourth and fifth bytes of the MAC address are?
The last 2 bytes of the IP address assigned to the server's physical network adapter, converted to hexadecimals.
Hyper-V Virtual Switches
The virtual switch enables your VMs to communicate with each other and access your physical network for Internet access; supports unlimited virtualized ports.
NIC teaming, (bonding/balancing/aggregation)
Windows feature that enables administrators to join multiple network adapters into a single entity, for performance enhancement or fault‐tolerance purposes. Hyper‐V virtual machines can also take advantage of NIC teaming, but they are limited to teams of only two, as opposed to the host operating system, which can have teams of up to 64 NICs.
What is a local area network (LAN)?
a network of hosts covering a small physical area, like an office, a floor in a building, or a small group of buildings. LANs are used to connect multiple hosts. These LANs are then connected to other LANs using a router, which (as discussed) is a layer‐3 device.
MAC spoofing
changes the MAC address of a network interface on a network device. Windows Network Load Balancing (NLB) is a form of clustering that allows multiple nodes to provide a server or application. Before you can use NLB, you need to enable spoofing of MAC addresses.
How many dynamically assigned MAC addresses can be provided by a Hyper-V server by default?
256
Enable MAC Address Spoofing
After enabled, the port in the virtual switch to which the virtual network adapter is connected can send and receive packets that contain any MAC address. The virtual switch port can also learn of new MAC addresses and add them in its forwarding table.
Switch Independent Mode:
All of the network adapters are connected to different switches, providing alternative routes through the network. Static teaming and LACP are switch dependent modes.
Swith Dependent Mode
All of the network adapters are connected to the same switch, providing a single interface with their combined bandwidth.
Hyper‐V includes three types of virtual switches:
External virtual switch: Creates a virtual switch that binds to the physical networkadapter. This enables your VMs to access your physical network. Starting with Windows Server 2016, you can map an external network to a wireless network adapter if you have installed the Wireless LAN service on the host Hyper‐V server and if the Hyper‐V server has a compatible network adapter. • Internal virtual switch: Creates a virtual switch that is used only by the VMs that run on the physical computer and between the VMs and the physical computer. • Private virtual switch: Creates a virtual switch that can only be used by the VMs running on the computer.
Optimizing Network Performance
First, you need to make sure that the physical network infrastructure is using at least 1 GB or faster links; it is recommended that you use the standard network adapters because they are faster than the legacy network adapters, and can reduce CPU overhead. You can also use VLANs, which help isolate networks, use bandwidth management to control the amount of traffic at one time, and use NIC teaming to provide larger bandwidth pipes. In addition, you can access network adapter hardware acceleration to enable virtual machine queue, IPsec task off‐loading, and single‐root I/O virtualization.
What are the benefits of VLANs over routed networks?
Higher performance on medium or large LANs due to reduced broadcast traffic • Better organization of devices on the network for easier management • Additional security because devices can be put on their own VLAN
Describe/Define Hyper-V virtualization
Hyper‐V virtualization provides virtual networks for the virtual machines to communicate with other virtual machines and it allows the virtual machines to communicate with the physical network infrastructure. Just like a physical network, the virtual devices connect to virtual switches, which can provide security, isolation, and service levels.
What are the two configurations of Switch Independent Mode?
The active/active configuration leaves all of the network adapters functional, providing increased throughput. If one adapter fails, all of the traffic is shunted to the remaining adapters. In the active/standby configuration, one adapter is left offline, to function as a failover in the event the active adapter fails. In active/active mode, an adapter failure causes a performance reduction; in active/standby mode, the performance remains the same before and after an adapter failure.
NIC teaming
This option enables the adapter to add its bandwidth to other adapters in the same guest operating system in a NIC teaming arrangement.
Port Mirroring Mode
This option enables the adapter to forward all the packets it receives over the network to another virtual adapter for analysis by using an application such as Network Monitor.
Enable DHCP guard
This option prevents the adapter from processing messages sent by rogue DHCP servers.
How can you add or remove network adapters to a virtual machine?
To add or remove network adapters to Generation 1 systems, or virtual machines running earlier than Windows 10 and Windows Server 2016, you must turn off the computer
What is the maximum number of ports supported by a Hyper‐V virtual switch?
Unlimited
Single‐root I/O virtualization (SR‐IOV)
allows a device, such as a network adapter, to distribute access to its resources among PCI Express hardware functions. You can configure a maximum number of off‐loaded security associations from 1 to 4,096. This feature is supported only on Hyper‐V standard network adapters.
Switch Embedded Teaming (SET)
allows you to use a Hyper‐V virtual switch to team up to eight physical Ethernet adapters located on the same Hyper‐V host into one or more software‐based virtual network adapters. The virtual network adapters will provide fast performance and fault tolerance in the event of a network adapter failure.
Virutal LANs (VLANS)
developed as an alternate solution to deploying multiple routers; logical network segments used to create separate broadcast domains, but they still allow the devices on the VLAN to communicate at layer 2 without requiring a router. ;created by switches, and traffic between VLANs is switched not routed, which creates a much faster network connection because there is no need for involvement of a routing protocol. Even though the hosts are logically separated, the traffic between these hosts is switched directly as if the hosts were on the same LAN segment.
IPsec task off‐loading
enables IPsec task off‐loading at the machine level, reducing the demands on the virtual machine's CPU by using a dedicated processor on the physical network adaptor. This feature is only supported on Hyper‐V‐specific network adapters.
A converged network allows for what different types of communication within a single network?
storage, video, and data communication. You can form a converged network by combining Switch Embedded Teaming (SET) with Remote Direct Memory Access (RDMA), which allows you to utilize fewer network adapters in your servers. RDMA was defined in Lesson 3.
The sixth and last byte of the MAC address contains?
the range of values from 00 to FF, which provides 256 possible addresses.
Why is it recommended that you use Hyper-V standard network adapters?
they communicate over the VMBus, which allows it to be faster than legacy network adapters. Hyper‐V standard network adapters are available for both Generation 1 and Generation 2 virtual machines. It requires a driver that is included in Hyper‐V Integration Services.
What is the challenge of an LAN? What is a solution to this challenge?
they grow larger is that each device on the LAN broadcasts traffic onto the LAN. Although these broadcasts will not cross a router, if there are enough hosts, the aggregate broadcast traffic can saturate a network.---- solution: Deploy more routers to divide the network into manageable segments
