VirtualNetworking

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Revision as of 16:46, 12 October 2010 by JustinClift (talk | contribs) (Typo fix, plus added initial diagram for the default libvirt virtual network configuration.)
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Virtual Networking

How the virtual networks used by guests work.


The default configuration

File:Virtual network default network overview.png

NAT

The other virtual network routing options

Forwarding

No routing

Restricting virtual network traffic to a specific interface

  • NOTE - Need to find out if it can be restricted to more than one interface.
    • i.e on a system with eth0/1/2, can we use the dev="" attribute in the network XML to restrict to (say) eth1&2 rather than only 1 interface?
  • NOTE - Not sure if virt-manager lets us configure this aspect of things.
    • If not, this will probably need to go under the "Advanced" category as it'll need to be configured through XML instead, or maybe in an overall "Filtering" topic like Dan Berrange wrote up.


DNS and DHCP

How DNS forwarding and DHCP setup work in libvirt.

dnsmasq

  • NOTE - dnsmasq apparently does more than just plain DNS forwarding, also including entries in the /etc/hosts (on the dnsmasq host) in what's returned to DNS queries.
    • Need to double check that's accurate, and if so document it. It sounds like a useful way of potentially overriding upstream DNS entries given to virtual guests


The Virtual Machine Manager (virt-manager)

  • The virtual network information available (through virt-manager)
    • Need to include which versions of virt-manager have this (ie from 0.x.y onwards)
    • Also need to list which drivers support this. ie qemu+ssh:// might, whereas qemu:// might not (that's an example only, but recent quick testing showed up some unexpected things here)
  • Creation of virtual network interfaces
  • Starting virtual network interfaces
  • Stopping virtual network interfaces
  • Deleting virtual network interfaces
  • Changing virtual network interface information
  • Stats collection in virt-manager
    • Need to include which versions of virt-manager have this (ie from 0.x.y onwards)
    • Implications of stats collection (performance impact?)
    • How to enable/disable collection of stats in virt-manager
    • Display of stats

Basic command line usage for virtual networks

Introduces the basic virsh net-* commands for virtual network management.

NO XML apart from dumping to check values

  • net-list
  • net-start
  • net-destroy
  • net-undefine
  • net-autostart
  • net-name
  • net-uuid
  • net-dumpxml
    • net-dumpxml included here rather than in "Advanced", as people don't need to understand the specifics in order to get value from this. i.e. people can see the MAC address without needing to deeply understand the other pieces


Advanced

Persistent vs non-persistent virtual networks

(ie net-create vs net-define)


XML format

Location of XML files on the host

virsh XML commands

  • net-define
  • net-create
  • net-edit

brctl commands ?

Should we include these at all? Unsure. Will know more when we get nearer to this bit.