In a dual stack deployment there may be a v4 and a v6 subnet on the same network.
There's also the case that a service provider has a notion of a public network, which is represented by a UUID. After a period of time, they may run out of IPs in one subnet, and want to assign another subnet as well, without forcing tenants to have to start using a new identifier for the public network. Of course, the provider would be responsible for creating L3 connectivity between the two subnets. Others can chime in, but those where the two cases that I remember. Dan On Mon, Aug 13, 2012 at 8:31 PM, Aaron Rosen <aro...@nicira.com> wrote: > The reason for this is because you can have multiple subnets on the same > L2 bcast domain. You can use ip aliasing in order to use multiple subnets > on one virtual nic. For example ifconfig eth0:1 a.b.c.d/24; ifconfig eth0:2 > d.e.f.g/24 > > Aaron > > > On Mon, Aug 13, 2012 at 7:52 PM, Takaaki Suzuki <suz...@midokura.com>wrote: > >> Hi all. >> >> I have one question. I prepared devstack with Qauntum V2. >> Now I can create Subnet for Network. >> And I can add multiple Subnet for one Network. VM can use multiple >> subnet for one virtual NIC? >> Why quantum v2 can create multiple subnet for one Network? >> >> quantum --os_token 1b73ace152c440ea939c2329fd115e56 --os_url >> http://localhost:9696/ net-list >> >> +----------------+--------------------------------------+-----------+--------+--------------------------------------+----------------------------------+ >> | admin_state_up | id | name | >> status | subnets | tenant_id >> | >> >> +----------------+--------------------------------------+-----------+--------+--------------------------------------+----------------------------------+ >> | True | d7a8106c-7ca6-4302-a065-6a87c859ed9c | test >> | ACTIVE | 474ea30c-9337-4f48-854c-9f572538a44c | >> 4fb66e3355304be5a6f3340d7067b369 | >> | | >> | | | >> 52ffda8c-61aa-465b-ae62-1ef57e9bed85 | >> | >> | | >> | | | >> 9a659285-c6b1-4e6f-b3f0-c3e37341e0be | >> | >> >> quantum --os_token 1b73ace152c440ea939c2329fd115e56 --os_url >> http://localhost:9696/ subnet-list >> >> +------------------------------------------------------+------------------+---------------+--------------------------------------+------------+--------+--------------------------------------+----------------------------------+ >> | allocation_pools | cidr >> | gateway_ip | id | ip_version >> | name | network_id | tenant_id >> | >> >> +------------------------------------------------------+------------------+---------------+--------------------------------------+------------+--------+--------------------------------------+----------------------------------+ >> | {"start": "192.168.100.2", "end": "192.168.100.254"} | >> 192.168.100.0/24 | 192.168.100.1 | >> 474ea30c-9337-4f48-854c-9f572538a44c | 4 | test01 | >> d7a8106c-7ca6-4302-a065-6a87c859ed9c | >> 4fb66e3355304be5a6f3340d7067b369 | >> | {"start": "192.168.210.2", "end": "192.168.210.254"} | >> 192.168.210.0/24 | 192.168.210.1 | >> 52ffda8c-61aa-465b-ae62-1ef57e9bed85 | 4 | test03 | >> d7a8106c-7ca6-4302-a065-6a87c859ed9c | >> 4fb66e3355304be5a6f3340d7067b369 | >> | {"start": "192.168.200.2", "end": "192.168.200.254"} | >> 192.168.200.0/24 | 192.168.200.1 | >> 9a659285-c6b1-4e6f-b3f0-c3e37341e0be | 4 | test02 | >> d7a8106c-7ca6-4302-a065-6a87c859ed9c | >> 4fb66e3355304be5a6f3340d7067b369 | >> >> +------------------------------------------------------+------------------+---------------+--------------------------------------+------------+--------+--------------------------------------+----------------------------------+ >> >> Thanks! >> Suzuki >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~openstack >> Post to : openstack@lists.launchpad.net >> Unsubscribe : https://launchpad.net/~openstack >> More help : https://help.launchpad.net/ListHelp >> > > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp > > -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Dan Wendlandt Nicira, Inc: www.nicira.com twitter: danwendlandt ~~~~~~~~~~~~~~~~~~~~~~~~~~~
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