libvirt users - Apr 2015 - Re: Remove Virtual bridge and DNSMASQ

I am running KVM virtualization with libvirtd (libvirt) 0.10.2  in bridged
network mode, however I still have the default virtual network
bridge/interfaces and dnsmasq on the host. What I am trying to understand
is whether or not dnsmasq and the virtual network (*virbr0, Vnet0 and Vnet1*)
still play any role. If not, can I remove them?

On most virtual hosts I see they are left around even when a network bridge
has been manually setup and  the default virtual network bridge/interfaces
and dnsmasq are not serve any purpose.

Thanks

Mimi


[bigfoot@localhost ~]$ ifconfig
br0       Link encap:Ethernet  HWaddr E2:59:52:12:34:4C
          inet addr:135.17.1XX.XX  Bcast:135.17.1XX.XX  Mask:255.255.255.128
          inet6 addr: fe80::ea39:35ff:fe12:948e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:564577 errors:0 dropped:0 overruns:0 frame:0
          TX packets:303315 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:566465184 (540.2 MiB)  TX bytes:83532692 (79.6 MiB)

eth0      Link encap:Ethernet  HWaddr E2:59:52:12:34:4C
          inet6 addr: fe80::ea39:35ff:fe12:948e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:806142 errors:0 dropped:0 overruns:0 frame:0
          TX packets:450977 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:711888772 (678.9 MiB)  TX bytes:175377460 (167.2 MiB)
          Interrupt:28 Memory:f7100000-f7120000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:276793 errors:0 dropped:0 overruns:0 frame:0
          TX packets:276793 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:551259266 (525.7 MiB)  TX bytes:551259266 (525.7 MiB)

*virbr0    Link encap:Ethernet  HWaddr 52:54:00:2A:1B:AF*
*          inet addr:192.168.122.1  Bcast:192.168.122.255
 Mask:255.255.255.0*
*          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1*
*          RX packets:0 errors:0 dropped:0 overruns:0 frame:0*
*          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0*
*          collisions:0 txqueuelen:0*
*          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)*

*vnet0     Link encap:Ethernet  HWaddr FE:54:00:A0:8D:50*
*          inet6 addr: fe80::fc54:ff:fea0:8d50/64 Scope:Link*
*          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1*
*          RX packets:124812 errors:0 dropped:0 overruns:0 frame:0*
*          TX packets:343055 errors:0 dropped:0 overruns:0 carrier:0*
*          collisions:0 txqueuelen:500*
*          RX bytes:55075362 (52.5 MiB)  TX bytes:138488556 (132.0 MiB)*

*vnet1     Link encap:Ethernet  HWaddr FE:54:00:71:A8:78*
*          inet6 addr: fe80::fc54:ff:fe71:a878/64 Scope:Link*
*          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1*
*          RX packets:17834 errors:0 dropped:0 overruns:0 frame:0*
*          TX packets:318816 errors:0 dropped:0 overruns:1 carrier:0*
*          collisions:0 txqueuelen:500*
*          RX bytes:2279102 (2.1 MiB)  TX bytes:20534286 (19.5 MiB)*

[bigfoot@localhost ~]$

On 24.04.2015 12:45, mimicafe@gmail.com wrote:
> I am running KVM virtualization with libvirtd (libvirt) 0.10.2  in bridged
> network mode, however I still have the default virtual network
> bridge/interfaces and dnsmasq on the host. What I am trying to understand
> is whether or not dnsmasq and the virtual network (*virbr0, Vnet0 and
Vnet1*)
> still play any role. If not, can I remove them?
Yes, you can safely remove libvirt-daemon-config-network package. It
should disable the default network. However, dropping dnsmasq is a bit
harder, since libivirt-daemon-driver-network depends on it. We can't
know whether you will not someday like a NATed network with a DHCP
server, even though now you don't. However,
libvirt-daemon-driver-network takes care about all the network types
known to libvirt, so you can't really drop it (unless forcibly removing
the package and let the libvirt just deal with it, which I'd discourage
you from doing anyway).

Michal

HI Michal


Thank you for explaining. I have this situation in a number of production
servers where we would always use static IPs for the host and VMs. In such
 case we have no requirement for NATed network in the future. And we we
ever do, we can rely on a DHCP server within the LAN to provide IPs to the
VMs.

I'll look to remove both  libivirt-daemon-driver-network,
libvirt-daemon-driver-network
and dnsmasq.

Any further thought from your side?

On 24 April 2015 at 13:12, Michal Privoznik <mprivozn@redhat.com> wrote:
> On 24.04.2015 12:45, mimicafe@gmail.com wrote:
> > I am running KVM virtualization with libvirtd (libvirt) 0.10.2  in
> bridged
> > network mode, however I still have the default virtual network
> > bridge/interfaces and dnsmasq on the host. What I am trying to
understand
> > is whether or not dnsmasq and the virtual network (*virbr0, Vnet0 and
> Vnet1*)
> > still play any role. If not, can I remove them?
>
> Yes, you can safely remove libvirt-daemon-config-network package. It
> should disable the default network. However, dropping dnsmasq is a bit
> harder, since libivirt-daemon-driver-network depends on it. We can't
> know whether you will not someday like a NATed network with a DHCP
> server, even though now you don't. However,
> libvirt-daemon-driver-network takes care about all the network types
> known to libvirt, so you can't really drop it (unless forcibly removing
> the package and let the libvirt just deal with it, which I'd discourage
> you from doing anyway).
>
> Michal
>