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[Quantum] Control the public IP address assigned to a router by quantum router-gateway-set

asked 2013-06-04 17:39:19 -0500

Short question: is it possible to control the IP address that is given to a router by the quantum router-gateway-set command ? In my setup, I have a physical Provider Network associated to a public (routable) IP address range used at my site (X.Y.Z.0/24). I have created an ExternalNet network by the CLI commands:

quantum net-create ExternalNet --router:external=True quantum subnet-create ExternalNet X.Y.Z.0/24 --enable_dhcp=False --gateway_ip=X.Y.Z.254

When I issue the quantum router-gateway-set command, the public interface of the router gets the first address of the X.Y.Z.0/24 range, i.e. X.Y.Z.1, which, by pure chance, is not used in my physical network. My setup seems to work OK, VMs are able to ping any other host in the external network X.Y.Z.0/24, as well as any other Internet host, through the physical router X.Y.Z.254.

I wonder if is possible to assign to the "virtual" router implemented in Quantum a given address in the range of addresses associated to the external subnet, e.g. X.Y.Z.33. This might also be useful in the "Per-tenant Routers with Private Networks" use case. Many thanks in advance for your replies. Roberto

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answered 2013-06-05 02:55:34 -0500

Try quantum subnet-create ExternalNet X.Y.Z.Q/24 --enable_dhcp=False --gateway_ip=X.Y.Z.254 Where X.Y.Z.Q is the ip you wanna set the router to.

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answered 2013-06-05 02:03:19 -0500

gongysh gravatar image

it IP of the public interface, qgxxx of router is from allocation pool of external network (--router:external=True). the allocation pool should not overlap with IPs of your physical network. why do u want to specify the quantum router's qgxx interface?

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answered 2013-06-06 07:24:51 -0500

@ Baohua Yang (yangbaohua): thanks for your suggestion, unfortunately it did not work to me, the router still gets the X.Y.Z.1 address

@ yong sheng gong (gongysh): maybe I am doing something conceptually wrong. My problem is that I can only use a sparse subset of addresses in the external X.Y.Z.0/24 public range. The IP address of the physical router is X.Y.Z.254. My target scenario is called "Provider Router with Private Networks" in the Quantum documentation (see ( for a reference). The IP address I would like to assign to my Provider Router is, say, X.Y.Z.33. My understanding is that I only need one public IP address, as I don't need public floating IP addresses to attach to specific VMs. If I restrict the size of the allocation pool to a small range including X.Y.X.33, I am not able to ping the physical router X.Y.X.254 from my VMs, and hence no Internet connectivity is allowed to them.

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answered 2013-06-07 00:51:51 -0500

gongysh gravatar image

It makes sense, I created a bug for it.

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Asked: 2013-06-04 17:39:19 -0500

Seen: 100 times

Last updated: Jun 07 '13