openstack team mailing list archive

[Dan Wendlandt <dan@xxxxxxxxxx>]

Hi Rangababu,

On Sat, Jul 23, 2011 at 12:58 PM, Rangababu Chakravarthula <
rbabu@xxxxxxxxxxxx> wrote:

> Couple of questions
> a) How can we address the max 4096 vlan's problem if each user want's a
> VLAN tagged network?
>

Currently, the notion of a VLAN is pretty central to the nova networking
code.

Removing this restriction and enabling more scalable network isolation
mechanisms is one of the motivations for the Quantum virtual network service
(see: http://wiki.openstack.org/Quantum).



> b) Docs says for each VLAN network, a dhcp server is started. How does it
> work when we do livemigrate?
>

Before and after the live migrate, the VM interface should be plugged into
the same ethernet broadcast domain, so everything will continue to work
(i.e., addresses from old DHCP lease remains valid, future DHCP requests
will go to the same DHCP server).

Dan




>
> thanks
>
>
> On Wed, Jul 20, 2011 at 11:56 PM, Thor Wolpert <thor@xxxxxxxxxx> wrote:
>
>> That was a great explanation, thanks!
>>
>> There is also a limit of 12 bits in the 802.1Q protocol, effectively
>> setting the max to 4096 vlans
>>
>> I so look forward to having that kind of problem :)!
>>
>>
>> On Wed, Jul 20, 2011 at 9:26 PM, Jeff Kramer <jeffkramer@xxxxxxxxx>wrote:
>>
>>> As I understand it, you can setup the tags in the switch first if you
>>> want, but you don't need to.  You will create VLAN tags in the Nova
>>> database as you create networks with 'nova-manage network create ...',
>>> and those will be assigned to users on a first-come first-serve basis.
>>>  When a user creates their first node nova assigns them an unused
>>> network which has a unique VLAN tag.  This tag is passed to
>>> nova-compute when your instance is started, and it feeds that VLAN tag
>>> into KVM which uses it for all network traffic in a way that's
>>> transparent to the guest OS.  When the guest talks to the network it
>>> uses that VLAN tag, which the nova-network node is also listening on.
>>>
>>> As long as your switch supports host-tagged VLANs (802.1Q), you don't
>>> have to create the tags in the switch before you use them.  You could
>>> setup all your VLANs before, someone else may have more experience
>>> with that.
>>>
>>> One wrinkle is that many switches have a set number of tagged VLANs
>>> they can support, for instance the HP V1810-24G switch that I'm using
>>> supports 64 tagged VLANs, which means my Nova cluster can only have 64
>>> different networks (or 64 different users).  The next model up
>>> supports 256, etc.  I assume that if you go over this number your
>>> network traffic will start dropping and weird things will happen.
>>>
>>> Your switch's management IPs should probably be in an address space
>>> that doesn't conflict with what you're assigning with nova.  If you're
>>> using 10.x.x.x for Nova you could put the switch on 192.168.x.x.  You
>>> probably shouldn't be touching the switch from a Nova guest, since the
>>> time you'll want to be fiddling with it will be when your Nova cluster
>>> is crashing or otherwise broken.
>>>
>>>
>>> On Wed, Jul 20, 2011 at 10:43 PM, tianyi wang <wangcity@xxxxxxxxx>
>>> wrote:
>>> > Hi, all
>>> >
>>> >
>>> >     If use VLAN mode, it's need setting VLAN in switch's NOS first?
>>> > And then the setting VLAN in nova controller node?
>>> >
>>> > Now, the switch's IP is 192.168.0.234 and the gateway ip address is
>>> > 192.168.0.1 ( in switch web management interface), should I change the
>>> > switch  IP and gateway to 10.0.0.x ?
>>> >
>>> > In VLAN mode, what's the relationship tween the controller node's VLAN
>>> > management and switch's NOS VLAN management?
>>> >
>>> > thanks
>>> >
>>> >
>>> > alex
>>> >
>>> > _______________________________________________
>>> > Mailing list: https://launchpad.net/~openstack
>>> > Post to     : openstack@xxxxxxxxxxxxxxxxxxx
>>> > Unsubscribe : https://launchpad.net/~openstack
>>> > More help   : https://help.launchpad.net/ListHelp
>>> >
>>>
>>>
>>>
>>> --
>>> Jeff Kramer
>>> jeffkramer@xxxxxxxxx
>>> http://www.jeffkramer.org/
>>>
>>> _______________________________________________
>>> Mailing list: https://launchpad.net/~openstack
>>> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
>>> Unsubscribe : https://launchpad.net/~openstack
>>> More help   : https://help.launchpad.net/ListHelp
>>>
>>
>>
>> _______________________________________________
>> Mailing list: https://launchpad.net/~openstack
>> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
>> Unsubscribe : https://launchpad.net/~openstack
>> More help   : https://help.launchpad.net/ListHelp
>>
>>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~openstack
> More help   : https://help.launchpad.net/ListHelp
>
>


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dan Wendlandt
Nicira Networks, Inc.
www.nicira.com | www.openvswitch.org
Sr. Product Manager
cell: 650-906-2650
~~~~~~~~~~~~~~~~~~~~~~~~~~~