The <pre/> section is rendered as-is on the page. That is, if all
the lines are prefixed with 4 spaces the rendered page will also
have them. Problem is if we put a box around such <pre/> because
the content might not fix into it.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
For some unknown reason the original implementation of the <forwarder>
element only took advantage of part of the functionality in the
dnsmasq feature it exposes - it allowed specifying the ip address of a
DNS server which *all* DNS requests would be forwarded to, like this:
<forwarder addr='192.168.123.25'/>
This is a frontend for dnsmasq's "server" option, which also allows
you to specify a domain that must be matched in order for a request to
be forwarded to a particular server. This patch adds support for
specifying the domain. For example:
<forwarder domain='example.com' addr='192.168.1.1'/>
<forwarder domain='www.example.com'/>
<forwarder domain='travesty.org' addr='10.0.0.1'/>
would forward requests for bob.example.com, ftp.example.com and
joe.corp.example.com all to the DNS server at 192.168.1.1, but would
forward requests for travesty.org and www.travesty.org to
10.0.0.1. And due to the second line, requests for www.example.com,
and odd.www.example.com would be resolved by the libvirt network's own
DNS server (i.e. thery wouldn't be immediately forwarded) even though
they also match 'example.com' - the match is given to the entry with
the longest matching domain. DNS requests not matching any of the
entries would be resolved by the libvirt network's own DNS server.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1331796
If you define a libvirt virtual network with one or more IP addresses,
it starts up an instance of dnsmasq. It's always been possible to
avoid dnsmasq's dhcp server (simply don't include a <dhcp> element),
but until now it wasn't possible to avoid having the DNS server
listening; even if the network has no <dns> element, it is started
using default settings.
This patch adds a new attribute to <dns>: enable='yes|no'. For
backward compatibility, it defaults to 'yes', but if you don't want a
DNS server created for the network, you can simply add:
<dns enable='no'/>
to the network configuration, and next time the network is started
there will be no dns server created (if there is dhcp configuration,
dnsmasq will be started with "port=0" which disables the DNS server;
if there is no dhcp configuration, dnsmasq won't be started at all).
The new forward mode 'open' is just like mode='route', except that no
firewall rules are added to assure that any traffic does or doesn't
pass. It is assumed that either they aren't necessary, or they will be
setup outside the scope of libvirt.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=846810
SRIOV VFs used in macvtap passthrough mode can take advantage of the
SRIOV card's transparent vlan tagging. All the code was there to set
the vlan tag, and it has been used for SRIOV VFs used for hostdev
interfaces for several years, but for some reason, the vlan tag for
macvtap passthrough devices was stubbed out with a -1.
This patch moves a bit of common validation down to a lower level
(virNetDevReplaceNetConfig()) so it is shared by hostdev and macvtap
modes, and updates the macvtap caller to actually send the vlan config
instead of -1.
When describing attributes and elements, we mostly stick to
a certain pattern; however, there are a few cases when the
information is not presented in the usual way.
Since there doesn't seem to be any reason not to follow the
tried and true formula, rework those bits to fit the rest of
the documentation.
This adds a new "localOnly" attribute on the domain element of the
network xml. With this set to "yes", DNS requests under that domain
will only be resolved by libvirt's dnsmasq, never forwarded upstream.
This was how it worked before commit f69a6b987d, and I found that
functionality useful. For example, I have my host's NetworkManager
dnsmasq configured to forward that domain to libvirt's dnsmasq, so I can
easily resolve guest names from outside. But if libvirt's dnsmasq
doesn't know a name and forwards it to the host, I'd get an endless
forwarding loop. Now I can set localOnly="yes" to prevent the loop.
Signed-off-by: Josh Stone <jistone@redhat.com>
The macTableManager attribute of a network's bridge subelement tells
libvirt how the bridge's MAC address table (used to determine the
egress port for packets) is managed. In the default mode, "kernel",
management is left to the kernel, which usually determines entries in
part by turning on promiscuous mode on all ports of the bridge,
flooding packets to all ports when the correct destination is unknown,
and adding/removing entries to the fdb as it sees incoming traffic
from particular MAC addresses. In "libvirt" mode, libvirt turns off
learning and flooding on all the bridge ports connected to guest
domain interfaces, and adds/removes entries according to the MAC
addresses in the domain interface configurations. A side effect of
turning off learning and unicast_flood on the ports of a bridge is
that (with Linux kernel 3.17 and newer), the kernel can automatically
turn off promiscuous mode on one or more of the bridge's ports
(usually only the one interface that is used to connect the bridge to
the physical network). The result is better performance (because
packets aren't being flooded to all ports, and can be dropped earlier
when they are of no interest) and slightly better security (a guest
can still send out packets with a spoofed source MAC address, but will
only receive traffic intended for the guest interface's configured MAC
address).
The attribute looks like this in the configuration:
<network>
<name>test</name>
<bridge name='br0' macTableManager='libvirt'/>
...
This patch only adds the config knob, documentation, and test
cases. The functionality behind this knob is added in later patches.
This new attribute will control whether or not libvirt will pay
attention to guest notifications about changes to network device mac
addresses and receive filters. The default for this is 'no' (for
security reasons). If it is set to 'yes' *and* the specified device
model and connection support it (currently only macvtap+virtio) then
libvirt will watch for NIC_RX_FILTER_CHANGED events, and when it
receives one, it will issue a query-rx-filter command, retrieve the
result, and modify the host-side macvtap interface's mac address and
unicast/multicast filters accordingly.
The functionality behind this attribute will be in a later patch. This
patch merely adds the attribute to the top-level of a domain's
<interface> as well as to <network> and <portgroup>, and adds
documentation and schema/xml2xml tests. Rather than adding even more
test files, I've just added the net attribute in various applicable
places of existing test files.
When the default was changed from kvm to vfio, the documentation for
hostdev and interface was changed, but the documentation in <network>
was forgotten.
Also document when the default was changed from "always kvm" to "vfio
if available, else kvm" (1.0.5).
Recent autotest/virt-test testing on f20 discovered an anomaly in how
the bandwidth options are documented and used. This was discovered due
to a bug fix in the /sbin/tc utility found in iproute-3.11.0.1 (on f20)
in which overflow was actually caught and returned as an error. The fix
was first introduced in iproute-3.10 (search on iproute2 commit 'a303853e').
The autotest/virt-test test for virsh domiftune was attempting to send
the largest unsigned integer value (4294967295) for maximum value
testing. The libvirt xml implementation was designed to manage values
in kilobytes thus when this value was passed to /sbin/tc, it (now)
properly rejected the 4294967295kbps value.
Investigation of the problem discovered that formatdomain.html.in and
formatnetwork.html.in described the elements and property types slightly
differently, although they use the same code - virNetDevBandwidthParseRate()
(shared by portgroups, domains, and networks xml parsers). Rather than
have the descriptions in two places, this patch will combine and reword
the description under formatnetwork.html.in and have formatdomain.html.in
link to that description.
This documentation faux pas was continued into the virsh man page where
the bandwidth description for both 'attach-interface' and 'domiftune'
did not indicate the format of each value, thus leading to the test using
largest unsigned integer value assuming "bps" rather than "kbps", which
ultimately was wrong.
https://bugzilla.redhat.com/show_bug.cgi?id=1057321
pointed out that we weren't honoring the <bandwidth> element in
libvirt networks using <forward mode='bridge'/>. In fact, these
networks are just a method of giving a libvirt network name to an
existing Linux host bridge on the system, and libvirt doesn't have
enough information to know where to set such limits. We are working on
a method of supporting network bandwidths for some specific cases of
<forward mode='bridge'/>, but currently libvirt doesn't support it. So
the proper thing to do now is just log an error when someone tries to
put a <bandwidth> element in that type of network. (It's unclear if we
will be able to do proper bandwidth limiting for macvtap networks, and
most definitely we will not be able to support it for hostdev
networks).
While looking through the network XML documentation and comparing it
to the networkValidate function, I noticed that we also ignore the
presence of a mac address in the config in the same cases, rather than
failing so that the user will understand that their desired action has
not been taken.
This patch updates networkValidate() (which is called any time a
persistent network is defined, or a transient network created) to log
an error and fail if it finds either a <bandwidth> or <mac> element
and the network forward mode is anything except 'route'. 'nat', or
nothing. (Yes, neither of those elements is acceptable for any macvtap
mode, nor for a hostdev network).
NB: This does *not* cause failure to start any existing network that
contains one of those elements, so someone might have erroneously
defined such a network in the past, and that network will continue to
function unmodified. I considered it too disruptive to suddenly break
working configs on the next reboot after a libvirt upgrade.
Useful to set custom forwarders instead of using the contents of
/etc/resolv.conf. It helps me to setup dnsmasq as local nameserver to
resolve VM domain names from domain 0, when domain option is used.
Signed-off-by: Diego Woitasen <diego.woitasen@vhgroup.net>
Signed-off-by: Eric Blake <eblake@redhat.com>
This resolves the issue that prompted the filing of
https://bugzilla.redhat.com/show_bug.cgi?id=928638
(although the request there is for something much larger and more
general than this patch).
commit f3868259ca disabled the
forwarding to upstream DNS servers of unresolved DNS requests for
names that had no domain, but were just simple host names (no "."
character anywhere in the name). While this behavior is frowned upon
by DNS root servers (that's why it was changed in libvirt), it is
convenient in some cases, and since dnsmasq can be configured to allow
it, it must not be strictly forbidden.
This patch restores the old behavior, but since it is usually
undesirable, restoring it requires specification of a new option in
the network config. Adding the attribute "forwardPlainNames='yes'" to
the <dns> elemnt does the trick - when that attribute is added to a
network config, any simple hostnames that can't be resolved by the
network's dnsmasq instance will be forwarded to the DNS servers listed
in the host's /etc/resolv.conf for an attempt at resolution (just as
any FQDN would be forwarded).
When that attribute *isn't* specified, unresolved simple names will
*not* be forwarded to the upstream DNS server - this is the default
behavior.
Somehow I put an example of a domain interface with a <vlan> element
into the network documentation.
This patch replaces that with an example of a network definition that
has a vlan element with trunk='yes', multiple tags, and even the new
nativeMode attribute. It also includes a <portgroup> that has a vlan
defined.
This patch adds functionality to allow libvirt to configure the
'native-tagged' and 'native-untagged' modes on openvswitch networks.
Signed-off-by: Laine Stump <laine@redhat.com>
network: static route support for <network>
This patch adds the <route> subelement of <network> to define a static
route. the address and prefix (or netmask) attribute identify the
destination network, and the gateway attribute specifies the next hop
address (which must be directly reachable from the containing
<network>) which is to receive the packets destined for
"address/(prefix|netmask)".
These attributes are translated into an "ip route add" command that is
executed when the network is started. The command used is of the
following form:
ip route add <address>/<prefix> via <gateway> \
dev <virbr-bridge> proto static metric <metric>
Tests are done to validate that the input data are correct. For
example, for a static route ip definition, the address must be a
network address and not a host address. Additional checks are added
to ensure that the specified gateway is directly reachable via this
network (i.e. that the gateway IP address is in the same subnet as one
of the IP's defined for the network).
prefix='0' is supported for both family='ipv4' address='0.0.0.0'
netmask='0.0.0.0' or prefix='0', and for family='ipv6' address='::',
prefix=0', although care should be taken to not override a desired
system default route.
Anytime an attempt is made to define a static route which *exactly*
duplicates an existing static route (for example, address=::,
prefix=0, metric=1), the following error message will be sent to
syslog:
RTNETLINK answers: File exists
This can be overridden by decreasing the metric value for the route
that should be preferred, or increasing the metric for the route that
shouldn't be preferred (and is thus in place only in anticipation that
the preferred route may be removed in the future). Caution should be
used when manipulating route metrics, especially for a default route.
Note: The use of the command-line interface should be replaced by
direct use of libnl so that error conditions can be handled better. But,
that is being left as an exercise for another day.
Signed-off-by: Gene Czarcinski <gene@czarc.net>
Signed-off-by: Laine Stump <laine@laine.org>
The rule generating the HTML docs passing the --html flag
to xsltproc. This makes it use the legacy HTML parser, which
either ignores or tries to fix all sorts of broken XML tags.
There's no reason why we should be writing broken XML in
the first place, so removing --html and adding the XHTML
doctype to all files forces us to create good XML.
This adds the XHTML doc type and fixes many, many XML tag
problems it exposes.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
A domain's <interface> or <hostdev>, as well as a <network>'s
<forward>, can now have an optional <driver name='kvm|vfio'/>
element. As of this patch, there is no functionality behind this new
knob - this patch adds support to the domain and network
formatter/parser, and to the RNG and documentation.
When the backend is added, legacy KVM PCI device assignment will
continue to be used when no driver name is specified (or if <driver
name='kvm'/> is specified), but if driver name is 'vfio', the new UEFI
Secure Boot compatible VFIO device assignment will be used.
Note that the parser doesn't automatically insert the current default
value of this setting. This is done on purpose because the two
possibilities are functionally equivalent from the guest's point of
view, and we want to be able to automatically start using vfio as the
default (even for existing domains) at some time in the future. This
is similar to what was done with the "vhost" driver option in
<interface>.
Originally, only a host name was used to associate a
DHCPv6 request with a specific IPv6 address. Further testing
demonstrates that this is an unreliable method and, instead,
a client-id or DUID needs to be used. According to DHCPv6
standards, this id can be a duid-LLT, duid-LL, or duid-UUID
even though dnsmasq will accept almost any text string.
Although validity checking of a specified string makes sure it is
hexadecimal notation with bytes separated by colons, there is no
rigorous check to make sure it meets the standard.
Documentation and schemas have been updated.
Signed-off-by: Gene Czarcinski <gene@czarc.net>
Signed-off-by: Laine Stump <laine@laine.org>
Let users set the port range to be used for forward mode NAT:
...
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
...
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Laine Stump <laine@laine.org>
Support setting which public ip to use for NAT via attribute
address in subelement <nat> in <forward>:
...
<forward mode='nat'>
<address start='1.2.3.4' end='1.2.3.10'/>
</forward>
...
This will construct an iptables line using:
'-j SNAT --to-source <start>-<end>'
instead of:
'-j MASQUERADE'
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Laine Stump <laine@laine.org>
The DHCPv6 support includes IPV6 dhcp-range and dhcp-host for one
IPv6 subnetwork on one interface. This support will only work
if dnsmasq version >= 2.64; otherwise an error occurs if
dhcp-range or dhcp-host is specified for an IPv6 address.
Essentially, this change provides the same DHCP support for IPv6
that has been available for IPv4.
With dnsmasq >= 2.64, support for the RA service is also now provided
by dnsmasq (radvd is no longer used/started). (Although at least one
version of dnsmasq prior to 2.64 "supported" IPv6 Router
Advertisement, there were bugs (fixed in 2.64) that rendered it
unusable.)
Documentation and the network schema has been updated
to reflect the new support.
This patch adds the capability for virtual guests to do IPv6
communication via a virtual network interface with no IPv6 (gateway)
addresses specified. This capability has always been enabled by
default for IPv4, but disabled for IPv6 for security concerns, and
because it requires the ip6tables command to be operational (which
isn't the case on a system with the ipv6 module completely disabled).
This patch adds a new attribute "ipv6" at the toplevel of a <network>
object. If ipv6='yes', the extra ip6tables rules required to permite
inter-guest communications are added when the network is started. If
it is 'no', or not present, those rules will not be added; thus the
default behavior doesn't change, so there should be no compatibility
issues with any existing installations.
Note that virtual guests cannot communication with the virtualization
host via this interface, because the following kernel tunable has
been set:
net.ipv6.conf.<bridge_interface_name>.disable_ipv6 = 1
This assures that the bridge interface will not have an IPv6
link-local (fe80::) address.
To control this behavior so that it is not enabled by default, the parameter
ipv6='yes' on the <network> statement has been added.
Documentation related to this patch has been updated.
The network schema has also been updated.
This patch updates the network driver to properly utilize the new
attributes/elements that are now in virNetworkDef
Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: Laine Stump <laine@laine.org>
The following config elements now support a <vlan> subelements:
within a domain: <interface>, and the <actual> subelement of <interface>
within a network: the toplevel, as well as any <portgroup>
Each vlan element must have one or more <tag id='n'/> subelements. If
there is more than one tag, it is assumed that vlan trunking is being
requested. If trunking is required with only a single tag, the
attribute "trunk='yes'" should be added to the toplevel <vlan>
element.
Some examples:
<interface type='hostdev'/>
<vlan>
<tag id='42'/>
</vlan>
<mac address='52:54:00:12:34:56'/>
...
</interface>
<network>
<name>vlan-net</name>
<vlan trunk='yes'>
<tag id='30'/>
</vlan>
<virtualport type='openvswitch'/>
</network>
<interface type='network'/>
<source network='vlan-net'/>
...
</interface>
<network>
<name>trunk-vlan</name>
<vlan>
<tag id='42'/>
<tag id='43'/>
</vlan>
...
</network>
<network>
<name>multi</name>
...
<portgroup name='production'/>
<vlan>
<tag id='42'/>
</vlan>
</portgroup>
<portgroup name='test'/>
<vlan>
<tag id='666'/>
</vlan>
</portgroup>
</network>
<interface type='network'/>
<source network='multi' portgroup='test'/>
...
</interface>
IMPORTANT NOTE: As of this patch there is no backend support for the
vlan element for *any* network device type. When support is added in
later patches, it will only be for those select network types that
support setting up a vlan on the host side, without the guest's
involvement. (For example, it will be possible to configure a vlan for
a guest connected to an openvswitch bridge, but it won't be possible
to do that for one that is connected to a standard Linux host bridge.)
Just as each physical device used by a network has a connections
counter, now each network has a connections counter which is
incremented once for each guest interface that connects using this
network.
The count is output in the live network XML, like this:
<network connections='20'>
...
</network>
It is read-only, and for informational purposes only - it isn't used
internally anywhere by libvirt.
One of the original ideas behind allowing a <virtualport> in an
interface definition as well as in the <network> definition *and*one
or more <portgroup>s within the network, was that guest-specific
parameteres (like instanceid and interfaceid) could be given in the
interface's virtualport, and more general things (portid, managerid,
etc) could be given in the network and/or portgroup, with all the bits
brought together at guest startup time and combined into a single
virtualport to be used by the guest. This was somehow overlooked in
the implementation, though - it simply picks the "most specific"
virtualport, and uses the entire thing, with no attempt to merge in
details from the others.
This patch uses virNetDevVPortProfileMerge3() to combine the three
possible virtualports into one, then uses
virNetDevVPortProfileCheck*() to verify that the resulting virtualport
type is appropriate for the type of network, and that all the required
attributes for that type are present.
An example of usage is this: assuming a <network> definitions on host
ABC of:
<network>
<name>testA</name>
...
<virtualport type='openvswitch'/>
...
<portgroup name='engineering'>
<virtualport>
<parameters profileid='eng'/>
</virtualport>
</portgroup>
<portgroup name='sales'>
<virtualport>
<parameters profileid='sales'/>
</virtualport>
</portgroup>
</network>
and the same <network> on host DEF of:
<network>
<name>testA</name>
...
<virtualport type='802.1Qbg'>
<parameters typeid="1193047" typeidversion="2"/>
</virtualport>
...
<portgroup name='engineering'>
<virtualport>
<parameters managerid="11"/>
</virtualport>
</portgroup>
<portgroup name='sales'>
<virtualport>
<parameters managerid="55"/>
</virtualport>
</portgroup>
</network>
and a guest <interface> definition of:
<interface type='network'>
<source network='testA' portgroup='sales'/>
<virtualport>
<parameters instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"
interfaceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"\>
</virtualport>
...
</interface>
If the guest was started on host ABC, the <virtualport> used would be:
<virtualport type='openvswitch'>
<parameters interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'
profileid='sales'/>
</virtualport>
but if that guest was started on host DEF, the <virtualport> would be:
<virtualport type='802.1Qbg'>
<parameters instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f"
typeid="1193047" typeidversion="2"
managerid="55"/>
</virtualport>
Additionally, if none of the involved <virtualport>s had a specified type
(this includes cases where no virtualport is given at all),
Hi,
this is the fifth version of my SRV record for DNSMasq patch rebased
for the current codebase to the bridge driver and libvirt XML file to
include support for the SRV records in the DNS. The syntax is based on
DNSMasq man page and tests for both xml2xml and xml2argv were added as
well. There are some things written a better way in comparison with
version 4, mainly there's no hack in tests/networkxml2argvtest.c and
also the xPath context is changed to use a simpler query using the
virXPathInt() function relative to the current node.
Also, the patch is also fixing the networkxml2argv test to pass both
checks, i.e. both unit tests and also syntax check.
Please review,
Michal
Signed-off-by: Michal Novotny <minovotn@redhat.com>
In a recent expansion of the documentation on network forward modes, I
incorrectly stated that incoming sessions to guests on routed networks
were blocked. This is true for guests on NATed networks, but not
routed. This patch corrects that error, and adds a pointer to the
nwfilter page for those who do want to restrict incoming sessions to
hosts on routed networks.
A few people have attempted to use the new forwarding modes with older
versions of libvirt. The docs where the modes are described have
always stated the minimum required libvirt version, but the examples
at the end didn't, which I believe is what has caused the confusion.
Similarly, the section on portgroups now has a version tag added at
the beginning.
I also noticed that there was no example of defining a <dns> hostname,
so I added one, as well as making the domain name example more
recognizable (by adding ".com" to the domain).
Someone in an IRC channel or an email pointed out a few days ago that
the examples of IPv6 addresses in the libvirt documentation were not
in the officially reserved "documentation" range. This addresses their
concern.
This should have been done with the rest of the patch for virtual
switch / network device abstraction. If documents the new elements
(and new usage of existing elements) in the <network> XML to support
libvirt networks that use existing host bridges and macvtap direct
connections, as well as the new <portgroup> element.
Every DomainNetDef has a bandwidth, as does every portgroup.
Whenever a DomainNetDef of type NETWORK is about to be used, a call is
made to networkAllocateActualDevice(). This function chooses the "best"
bandwidth object and places it in the DomainActualNetDef.
From that point on, whenever some code needs to use the bandwidth data
for the interface, it's retrieved with virDomainNetGetActualBandwidth(),
which will always return the "best" info as determined in the
previous step.
Define new 'bandwidth' element with possible child element 'inbound'
and 'outbound' addressing incoming and outgoing traffic respectively:
<bandwidth>
<inbound average='1000' peak='2000' burst='5120'/>
<outbound average='500'/>
</bandwidth>
Leaving any element out means not to shape traffic in that
direction.
The units for average and peak (rate) are in kilobytes per second,
for burst (size) are just in kilobytes.
This element can be inserted into domain's 'interface' and
'network'.
The sub-elements of <ip> had been placed at the same level of
indentation as ip itself, implying that they were really elements of
<network>. Within that, sub-elements of ip/dhcp were also at that same
level. These have been double-indented.
At the same time, I realized that the documentation for the new <dns>
element had been placed right in the middle of the description of the
sub-elements of <ip>. I moved it up out of the way.
This commit introduces names definition for the DNS hosts file using
the following syntax:
<dns>
<host ip="192.168.1.1">
<name>alias1</name>
<name>alias2</name>
</host>
</dns>
Some of the improvements and fixes were done by Laine Stump so
I'm putting him into the SOB clause again ;-)
Signed-off-by: Michal Novotny <minovotn@redhat.com>
Signed-off-by: Laine Stump <laine@laine.org>
This commit introduces the <dns> element and <txt> record for the
virtual DNS network. The DNS TXT record can be defined using following
syntax in the network XML file:
<dns>
<txt name="example" value="example value" />
</dns>
Also, the Relax-NG scheme has been altered to allow the texts without
spaces only for the name element and some nitpicks about memory
free'ing have been fixed by Laine so therefore I'm adding Laine to the
SOB clause ;-)
Signed-off-by: Michal Novotny <minovotn@redhat.com>
Signed-off-by: Laine Stump <laine@laine.org>
It was just pointed out that, although I added documentation for the
IPv6 additions to the network XML, I neglected to use those additions
in the examples. This patch adds an IPv6 address to each of the
examples except for the "default" network, since that is a faithful
reproduction of the default network config that's automatically
installed, which doesn't include any IPv6 address (for good reason -
because there is no such thing as IPv6 NAT, there is no one IPv6
address that would work for all installations).
