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 <jeffkra...@gmail.com> 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 <wangc...@gmail.com> 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@lists.launchpad.net > > Unsubscribe : https://launchpad.net/~openstack > > More help : https://help.launchpad.net/ListHelp > > > > > > -- > Jeff Kramer > jeffkra...@gmail.com > http://www.jeffkramer.org/ > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp >
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