xl-network-configuration - XL Network Configuration Syntax
This document specifies the xl config file format vif configuration option. It
has the following form:
vif = [ '<vifspec>', '<vifspec>', ... ]
where each vifspec is in this form:
'' # The empty string
These might be specified in the domain config file like this:
vif = [ 'mac=00:16:3E:74:34:32', 'mac=00:16:3e:5f:48:e4,bridge=xenbr1' ]
More formally, the string is a series of comma-separated keyword/value pairs.
All keywords are optional.
Each device has a "DEVID" which is its index within the vif list,
starting from 0.
If specified then this option specifies the MAC address inside the guest of this
VIF device. The value is a 48-bit number represented as six groups of two
hexadecimal digits, separated by colons (:).
The default if this keyword is not specified is to be automatically generate a
MAC address inside the space assigned to Xen's Organizationally Unique
If you are choosing a MAC address then it is strongly recommend to follow one of
the following strategies:
- Generate a random sequence of 6 byte, set the locally administered bit
(bit 2 of the first byte) and clear the multicast bit (bit 1 of the first
byte). In other words the first byte should have the bit pattern xxxxxx10
(where x is a randomly generated bit) and the remaining 5 bytes are
randomly generated See [http://en.wikipedia.org/wiki/MAC_address] for more
details the structure of a MAC address.
- Allocate an address from within the space defined by your organization's
OUI (if you have one) following your organization's procedures for doing
- Allocate an address from within the space defined by Xen's OUI (00:16:3e).
Taking care not to clash with other users of the physical network segment
where this VIF will reside.
If you have an OUI for your own use then that is the preferred strategy.
Otherwise in general you should prefer to generate a random MAC and set the
locally administered bit since this allows for more bits of randomness than
using the Xen OUI.
Specifies the name of the network bridge which this VIF should be added to. The
default is "xenbr0". The bridge must be configured using your
distribution's network configuration tools. See the wiki
<http://wiki.xen.org/wiki/HostConfiguration/Networking> for guidance and
Specifies the name of the network interface which has an IP and which is in the
network the VIF should communicate with. This is used in the host by the
vif-route hotplug script. See wiki <http://wiki.xen.org/wiki/Vif-route>
for guidance and examples.
NOTE: netdev is a deprecated alias of this option.
This keyword is valid for HVM guests only.
Specifies the type of device to valid values are:
- "ioemu" (default) -- this device will be provided as an emulate
device to the guest and also as a paravirtualised device which the guest
may choose to use instead if it has suitable drivers available.
- "vif" -- this device will be provided as a paravirtualised
This keyword is valid for HVM guest devices with "type=ioemu" only.
Specifies the type device to emulated for this guest. Valid values are:
- "rtl8139" (default) -- Realtek RTL8139
- "e1000" -- Intel E1000
- in principle any device supported by your device model
Specifies the backend device name for the virtual device.
If the domain is an HVM domain then the associated emulated (tap) device will
have a "-emu" suffice added.
The default name for the virtual device is "vifDOMID.DEVID" where
"DOMID" is the guest domain ID and "DEVID" is the device
number. Likewise the default tap name is "vifDOMID.DEVID-emu".
Specifies the hotplug script to run to configure this device (e.g. to add it to
the relevant bridge). Defaults to "XEN_SCRIPT_DIR/vif-bridge" but
can be set to any script. Some example scripts are installed in
Specifies the IP address for the device, the default is not to specify an IP
What, if any, effect this has depends on the hotplug script which is configured.
A typically behaviour (exhibited by the example hotplug scripts) if set might
be to configure firewall rules to allow only the specified IP address to be
used by the guest (blocking all others).
Specifies the backend domain which this device should attach to. This defaults
to domain 0. Specifying another domain requires setting up a driver domain
which is outside the scope of this document.
Specifies the rate at which the outgoing traffic will be limited to. The default
if this keyword is not specified is unlimited.
The rate may be specified as "/s" or optionally "/s@".
- "RATE" is in bytes and can accept suffixes:
- GB, MB, KB, B for bytes.
- Gb, Mb, Kb, b for bits.
- "INTERVAL" is in microseconds and can accept suffixes: ms, us,
s. It determines the frequency at which the vif transmission credit is
replenished. The default is 50ms.
Vif rate limiting is credit-based. It means that for "1MB/s@20ms", the
available credit will be equivalent of the traffic you would have done at
"1MB/s" during 20ms. This will results in a credit of 20,000 bytes
replenished every 20,000 us.
'rate=10Mb/s' -- meaning up to 10 megabits every second
'rate=250KB/s' -- meaning up to 250 kilobytes every second
'rate=1MB/s@20ms' -- meaning 20,000 bytes in every 20 millisecond period
NOTE: The actual underlying limits of rate limiting are dependent on the
underlying netback implementation.
Specifies the devid manually instead of letting xl choose the lowest index
NOTE: This should not be set unless you have a reason to.