Re: [ovirt-users] Confused by logical networks

[Paul-Erik Törrönen]

On 2018-02-23 08:41, Yaniv Kaul wrote:

There's no reason really to assign IPs to hosts on the logical network.


Ah yes, you're correct.

I was using the physical host as a GW so that the VMs on the logical 
network would have an access point to outside (like the CentOS 
repositories).


Anyways, I found the cause of my confusion in the end. The switch was 
not properly set up (*ahemm* forgot to save configuration).


3 thumbs up for oVirt showing the LLDP-info of the switch :-)

And the fact that despite having to reinstall essentially everything 
oVirt from scratch (due to failed upgrade), the VMs were just a matter 
if import. Splendid work!


Poltsi
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Re: [ovirt-users] Confused by logical networks

[Yaniv Kaul]

On Feb 22, 2018 5:26 PM, "Paul-Erik Törrönen"  wrote:

I'm not sure how the logical networks should work and would appreciate if
someone could shed some light into the matter, I've tried reading the
documentation¹ but have not become any wiser :-/

For the sake of argument, I have two hosts in the same cluster/DC, They
both have 2 network devices each (let's call them eth0 and eth1). On both
hosts the ovirtmgmgt is connected to eth0 and uses the 10.0.0.0/8-network.
Host 1 is 10.0.0.1 and host 2 is 10.0.0.2. All four network devices are
connected to one switch.

Then I create a logical network, mylogic which should be 192.168.1.0/24,
which I assign to eth1 on each host, but define only for host 1 an
ip-address, 192.168.1.1, host 2 has also the network assigned to eth1, but
withouth an ip address.


There's no reason really to assign IPs to hosts on the logical network.
oVirt provides layer 2 (L2) connectivity to VMs. Whatever DHCP, DNS or
gateway is on that network, they'll use. It should not be one of the hosts.
Their interfaces just bridge the VM traffic over to the designated network,
nothing more.
Y.


Next I create vm1 on host 1, give it a single virtual network connection to
mylogic, and configure the guest to use 192.168.1.2 with gw 192.168.1.1.
Obviously I can from the guest ping 192.168.1.1 which is the host address
on the logical network as the guest is running on the same hardware where
the host ip address is defined.

However, and this is where my confusion lies, if I now create another vm,
vm2, on host 2, attach its network device to the mylogic network and
configure it to use 192.168.1.3 with gw 192.168.1.1, I can not ping neither
192.168.1.1 nor 192.168.1.2.

My understanding is that vm2 should be able to ping the wm1 as well as the
gateway address defined on host 1. However this does not seem to be the
case.

What have I missed here?

TIA,

Poltsi

¹ https://www.ovirt.org/documentation/admin-guide/chap-Logical_Networks/
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Re: [ovirt-users] Confused by logical networks

[Vincent Royer]

should work out for you then.  In my case I was trying to do it all just
with static addressing without dns entries and I quickly learned that it's
just not designed to operate that way.

Cheers

*Vincent Royer*
*778-825-1057*



*SUSTAINABLE MOBILE ENERGY SOLUTIONS*




On Thu, Feb 22, 2018 at 9:16 PM, Paul-Erik Törrönen 
wrote:

> On 2018-02-22 22:56, Vincent Royer wrote:
>
>> Hope some part of this helps you!
>>
>
> Thanks for your answer, I need to digest it more in detail, but it seems
> like I indeed have missed some essential parts.
>
> I'll come back with a more detailed result later, but for the record, I do
> have a DNS server that I can manage completely in this case, and the switch
> management is also accessible to me.
>
> Poltsi
>
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Re: [ovirt-users] Confused by logical networks

[Paul-Erik Törrönen]

On 2018-02-22 22:56, Vincent Royer wrote:

Hope some part of this helps you!


Thanks for your answer, I need to digest it more in detail, but it seems 
like I indeed have missed some essential parts.


I'll come back with a more detailed result later, but for the record, I 
do have a DNS server that I can manage completely in this case, and the 
switch management is also accessible to me.


Poltsi
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Re: [ovirt-users] Confused by logical networks

[Vincent Royer]

I had similar confusion, and trying to assign static IPs was just not
working for me.

Here is how I got it to work:

#1 you absolutely require a DNS server you can add entries to.  I tried to
go without, and it just does not work.

For me, management network is on vlan 10, so each host grabs a 172.16.10.xx
address.  The oVirt engine (self hosted) also grabs an address in this
subnet. I look in the DHCP leases and turn those into static assignments in
the router, but left the config on the hosts to DHCP.  Add those IPs to
your DNS so that you can reach each host, and the engine, at
hostname.domain.net (or whatever your fully qualified domain name is for
each)

Now, set your VM network to DHCP on a different, specific VLAN.  Set that
vlan up in your router with a small DHCP pool, only big enough for the VMs
you want to run. Make sure you allow that vlan through to the switchports
connected to the nic you are using for your VMs.

For me, the VMs are on vlan 30, so the subnet is 172.16.30.xx. Each VM
boots up, makes a DHCP request on vlan 30, and is assigned an address.
Then again go into your router and make this a static entry, leaving the
config in the VM to DHCP.  Once you install the agent in the VM, the IP
will show up in the engine GUI.  Then you can assign an FQDN to each vm's
IP I'm your DNS server.

Set up this way, I can migrate the VM to whichever host, and still access
it over RDP by it's FQDN.

I also have dual NICs but I set mine up as a team (bridge) instead of one
for MGMT and one for VMs.   That way, I can also unplug anyone Ethernet
cable from any machine, and nothing happens, both the MGMT and VM network
keep ticking away happily.  I have each NIC plugged into a separate switch
chassis, to gain redundancy on the switches.

Hope some part of this helps you!


On Feb 22, 2018 7:25 AM, "Paul-Erik Törrönen"  wrote:

> I'm not sure how the logical networks should work and would appreciate if
> someone could shed some light into the matter, I've tried reading the
> documentation¹ but have not become any wiser :-/
>
> For the sake of argument, I have two hosts in the same cluster/DC, They
> both have 2 network devices each (let's call them eth0 and eth1). On both
> hosts the ovirtmgmgt is connected to eth0 and uses the 10.0.0.0/8-network.
> Host 1 is 10.0.0.1 and host 2 is 10.0.0.2. All four network devices are
> connected to one switch.
>
> Then I create a logical network, mylogic which should be 192.168.1.0/24,
> which I assign to eth1 on each host, but define only for host 1 an
> ip-address, 192.168.1.1, host 2 has also the network assigned to eth1, but
> withouth an ip address.
>
> Next I create vm1 on host 1, give it a single virtual network connection
> to mylogic, and configure the guest to use 192.168.1.2 with gw 192.168.1.1.
> Obviously I can from the guest ping 192.168.1.1 which is the host address
> on the logical network as the guest is running on the same hardware where
> the host ip address is defined.
>
> However, and this is where my confusion lies, if I now create another vm,
> vm2, on host 2, attach its network device to the mylogic network and
> configure it to use 192.168.1.3 with gw 192.168.1.1, I can not ping neither
> 192.168.1.1 nor 192.168.1.2.
>
> My understanding is that vm2 should be able to ping the wm1 as well as the
> gateway address defined on host 1. However this does not seem to be the
> case.
>
> What have I missed here?
>
> TIA,
>
> Poltsi
>
> ¹ https://www.ovirt.org/documentation/admin-guide/chap-Logical_Networks/
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[ovirt-users] Confused by logical networks

[Paul-Erik Törrönen]

I'm not sure how the logical networks should work and would appreciate 
if someone could shed some light into the matter, I've tried reading the 
documentation¹ but have not become any wiser :-/


For the sake of argument, I have two hosts in the same cluster/DC, They 
both have 2 network devices each (let's call them eth0 and eth1). On 
both hosts the ovirtmgmgt is connected to eth0 and uses the 
10.0.0.0/8-network. Host 1 is 10.0.0.1 and host 2 is 10.0.0.2. All four 
network devices are connected to one switch.


Then I create a logical network, mylogic which should be 192.168.1.0/24, 
which I assign to eth1 on each host, but define only for host 1 an 
ip-address, 192.168.1.1, host 2 has also the network assigned to eth1, 
but withouth an ip address.


Next I create vm1 on host 1, give it a single virtual network connection 
to mylogic, and configure the guest to use 192.168.1.2 with gw 
192.168.1.1. Obviously I can from the guest ping 192.168.1.1 which is 
the host address on the logical network as the guest is running on the 
same hardware where the host ip address is defined.


However, and this is where my confusion lies, if I now create another 
vm, vm2, on host 2, attach its network device to the mylogic network and 
configure it to use 192.168.1.3 with gw 192.168.1.1, I can not ping 
neither 192.168.1.1 nor 192.168.1.2.


My understanding is that vm2 should be able to ping the wm1 as well as 
the gateway address defined on host 1. However this does not seem to be 
the case.


What have I missed here?

TIA,

Poltsi

¹ https://www.ovirt.org/documentation/admin-guide/chap-Logical_Networks/
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