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Document network input panel

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Emmanuel Kasper 2016-06-09 13:26:44 +02:00 committed by Dietmar Maurer
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@ -273,6 +273,65 @@ systems.
When allocating RAMs to your VMs, a good rule of thumb is always to leave 1GB
of RAM available to the host.
Network Device
~~~~~~~~~~~~~~
Each VM can have many _Network interface controllers_ (NIC), of four different
types:
* *Intel E1000* is the default, and emulates an Intel Gigabit network card.
* the *VirtIO* paravirtualized NIC should be used if you aim for maximum
performance. Like all VirtIO devices, the guest OS should have the proper driver
installed.
* the *Realtek 8139* emulates an older 100 MB/s network card, and should
only be used when emulating older operating systems ( released before 2002 )
* the *vmxnet3* is another paravirtualized device, which should only be used
when importing a VM from another hypervisor.
{pve} will generate for each NIC a random *MAC address*, so that your VM is
addressable on Ethernet networks.
If you are using the VirtIO driver, you can optionally activate the
*Multiqueues* option. This option allows the guest OS to process networking
packets using multiple virtual CPUs, providing an increase in the total number
of packets transfered.
//http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html
When using the VirtIO driver with {pve}, each NIC network queue is passed to the
host kernel, where the queue will be processed by a kernel thread spawn by the
vhost driver. With this option activated, it is possible to pass _multiple_
network queues to the host kernel for each NIC.
//https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Virtualization_Tuning_and_Optimization_Guide/sect-Virtualization_Tuning_Optimization_Guide-Networking-Techniques.html#sect-Virtualization_Tuning_Optimization_Guide-Networking-Multi-queue_virtio-net
When using Multiqueues, it is recommended to set it to a value equal
to the number of Total Cores of your guest. You also need to set in
the VM the number of multi-purpose channels on each VirtIO NIC with the ethtool
command:
`ethtool -L eth0 combined X`
where X is the number of the number of vcpus of the VM.
You should note that setting the Multiqueues parameter to a value greater
than one will increase the CPU load on the host and guest systems as the
traffic increases. We recommend to set this option only when the VM has to
process a great number of incoming connections, such as when the VM is running
as a router, reverse proxy or a busy HTTP server doing long polling.
The NIC you added to the VM can follow one of two differents models:
* in the default *Bridged mode* each virtual NIC is backed on the host by a
_tap device_, ( a software loopback device simulating an Ethernet NIC ). This
tap device is added to a bridge, by default vmbr0 in {pve}. In this mode, VMs
have direct access to the Ethernet LAN on which the host is located.
* in the alternative *NAT mode*, each virtual NIC will only communicate with
the Qemu user networking stack, where a builting router and DHCP server can
provide network access. This built-in DHCP will serve adresses in the private
10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and
should only be used for testing.
You can also skip adding a network device when creating a VM by selecting *No
network device*.
USB Passthrough
~~~~~~~~~~~~~~~
There are two different types of USB passthrough devices: