CARP within VirtualBox Does it work?

[dweimer]

On 2012-11-30 13:44, dweimer wrote:
> On 2012-11-29 14:07, dweimer wrote:
>> On 2012-11-29 12:53, Fleuriot Damien wrote:
>>> On Nov 29, 2012, at 6:43 PM, dweimer <dweimer at dweimer.net> wrote:
>>>
>>>> I was trying to setup a test of CARP on two virtual machines 
>>>> running in VirtualBox 4.2.4r81684 I am not sure if I have something 
>>>> wrong with my CARP configuration or if VirtualBox just doesn't work 
>>>> right with it.  I can only ping the CARP interface IP address from 
>>>> the machine listed as MASTER, if I do an ifconfig carp0 down on the 
>>>> MASTER the other machine correctly switches form BACKUP to MASTER 
>>>> and then I can ping the interface from it but not from the Original 
>>>> system.
>>>>
>>>> The VirtualBox systems are both using bridged networking, and the 
>>>> host cannot ping the carp0 IP address but can ping the interface IP 
>>>> address.
>>>>
>>>> Before I go through more trouble shooting, does anyone know if 
>>>> CARP doesn't work with VirtualBox?
>>>>
>>>> carp configuration
>>>> Machine1:
>>>> ifconfig_em0="UP"
>>>> ifconfig_em0_name="LAN"
>>>> ipv4_addrs_LAN="10.20.190.201/16"
>>>> defaultrouter="10.20.111.2"
>>>> cloned_interfaces="carp0"
>>>> ifconfig_carp0="vhid 1 advskew 100 pass ReduntantCarpTest 
>>>> 10.20.190.203/16
>>>>
>>>> ifconfig carp0:
>>>> carp0 flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
>>>> inet 10.20.190.203 netmask 0xffff0000
>>>> nd6 options=29<PREFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>>>> carp: MASTER vhid 1 advbase 1 advskew 100
>>>>
>>>>
>>>> Machine2:
>>>> ifconfig_em0="UP"
>>>> ifconfig_em0_name="LAN"
>>>> ipv4_addrs_LAN="10.20.190.202/16"
>>>> defaultrouter="10.20.111.2"
>>>> cloned_interfaces="carp0"
>>>> ifconfig_carp0="vhid 1 pass ReduntantCarpTest 10.20.190.203/16
>>>>
>>>> ifconfig carp0:
>>>> carp0 flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
>>>> inet 10.20.190.203 netmask 0xffff0000
>>>> nd6 options=29<PREFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>>>> carp: BACKUP vhid 1 advbase 1 advskew 0
>>>>
>>>> FreeBSD version is 9.1RC3 on both test machines.
>>>
>>>
>>>
>>> We're using FreeBSD and CARP in virtualized environments at work,
>>> albeit not on VirtualBox but on Proxmox/KVM.
>>>
>>> First, I would advise replacing 10.20.190.203/16 with 
>>> 10.20.190.203/32
>>>
>>>
>>> I notice your carp0 is MASTER on machine1 with an advskew of 100 vs
>>> machine 2 advskew 0, same advbase.
>>> Confirm this is *after* you've set carp0 down on machine2.
>>>
>>> If both carps are up and machine1 with advskew 100 beats machine2
>>> with advskew 0, you have an additional problem.
>>>
>>>
>>> See if you have any more luck with the /32 address on carp0 anyway.
>>
>> The documentation shows the mask matching that of the interface:
>> hostname="hostb.example.org"
>> ifconfig_fxp0="inet 192.168.1.4 netmask 255.255.255.0"
>> cloned_interfaces="carp0"
>> ifconfig_carp0="vhid 2 pass testpass 192.168.1.51/24"
>>
>> This is consistent with the man page for CARP on the system as well.
>> Regardless I tried with the /32 and had the same result as I did 
>> with
>> the /16.  I had done various UP/DOWN on interfaces so the current
>> MASTER was just the last one to have not been DOWN.  I think I might
>> just copy these VMs to my VMWARE Workstation 9 install on my home PC
>> after work tonight and see if the problem persists.
>
> The behavior definitely changed going from VirtualBox to VMWare, the
> only change in my configuration was the IP addresses to match the 
> home
> network.  However now I can talk to the carp interface form other
> machines, but they receive two response one from each of the test
> systems.  TCPDUMP shows that they are each seeing the others
> broadcasts, but for some reason they are both running as MASTER.  If
> you run a DOWN/UP on the interface, it briefly shows as BACKUP before
> switching to MASTER.  I tried with both /24 subnet of my home 
> network,
> and setting the carp0 interface to /32, both behaved the same.  Any
> one have any other ideas, as to whether this comes down to a Virtual
> Network Issue, or a setup issue on my part.

I forgot to mention I did verify that the inet.carp.arpbalance is set 
at its default of 0 which should be disabled on both systems.

-- 
Thanks,
    Dean E. Weimer
    http://www.dweimer.net/