Open Stack

On 22/04/16 10:59, Remco wrote:
> Hi,

Hi Remco,

> We are running Liberty, with provider networks. We use the Neutron DHCP
> agent to configure IPv4 and IPv6 addresses for instances. This is all
> working great, however we sometimes need to put multiple subnets on one
> VLAN interface (for legacy reasons). This is in fact also working,
> however it configures some unwanted routes.
>
> For example, the following subnets exist in a Neutron network:
>
> 192.168.10.0/24 <http://192.168.10.0/24>
> 192.168.11.0/24 <http://192.168.11.0/24>
> 192.168.12.0/24 <http://192.168.12.0/24>
>
> I.e. if the IP address obtained is 192.168.10.8/24
> <http://192.168.10.8/24>, the following routes are inserted:

Do you mean on the instance?

> 192.168.10.0/24 <http://192.168.10.0/24> with gateway 0.0.0.0
> 192.168.11.0/24 <http://192.168.11.0/24> with gateway 0.0.0.0
> 192.168.12.0/24 <http://192.168.12.0/24> with gateway 0.0.0.0

Does 'with gateway 0.0.0.0' mean directly connected?  What precisely 
does 'ip r' show?

(I've never seen, e.g., '192.168.10.0/24 via 0.0.0.0' before, and don't 
know how I would interpret that.  So guessing you mean '192.168.10.0/24 
dev eth0'.)

> The first route is obviously not an issue, as this route is directly
> connected, but the other routes are plain wrong and stop traffic from
> being routed to the default gateway.
>
> Does anyone know how to disable this behavior? I only want a default
> gateway obtained from DHCP and I do not need any further routes.

Do you know what is creating the .11 and .12 routes?  Unless you have 
host routes in your subnet config, I would expect the instance only to 
create a route for its DHCP-issued address, and hence only for .10.

	Neil