Openstack provider network

asked 2020-01-06 18:38:36 -0500

happy75 gravatar image

HI Openstack Networking experts,

I have 2 questions: I understand that there are 2 types of network in Openstack: (a) Provider network and (b) Tenant network (1) i have created my private cloud using the provider network option. It seems that I can't even create any network/subnet using the dashboard and this is logging in as the admin user. When I tried to create the network, I got an error message saying that "Unable to create network. No tenant network is available for allocation...". Is this normal? I mean as the admin user, shouldn't I be able to create the network even from the dashboard? Because of this error, I went to create the network and subnet as per the following link and it works, does anybody know why it is okay to create network from the CLI but not okay to do it from dashboard? Am I doing something wrong? https://docs.openstack.org/newton/install-guide-ubuntu/launch-instance-networks-provider.html (https://docs.openstack.org/newton/ins...)

(2) I have allocated the default IP address to my controller and compute node (they are 10.0.0.11 and 10.0.0.31 respectively). Is it okay to use the provider network option if my private cloud is NOT connected to the outside world (internet)? Sorry i am a bit confused as to when to use the provider network and when to tenant network option. I understand the tenant network option is used if you want your users to be able create their own network etc but how does that affect the IP addresses you select for the VMs? For provider network option, does that mean that i can create virtual network inside Openstack using any IP addresses (i.e. any IP addresses that are not used on my network) and then the vm will be able to communicate to each other? What is the recommendation for the sort of IP addresses I should be allocated to the virtual instances, i.e. should it be in the same subnet as the controller and compute node (so 10.0.0.x in my case)? It says on the official Openstack doco that "For provider network option, an instance uses a provider (external) network that connects to the physical network infrastructure via layer-2 (bridging/switching). This network includes a DHCP server that provides IP addresses to instances".

Many thanks in advance!

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answered 2020-01-06 23:58:21 -0500

i have created my private cloud using the provider network option. It seems that I can't even create any network/subnet using the dashboard

I don't think that the dashboard allows you to create provider networks. If it does, you may have to click a box or so to indicate that it's a provider network you want.

Is it okay to use the provider network option if my private cloud is NOT connected to the outside world (internet)?

Yes. Of course, your instances won't be able to connect to the internet either. Devstack and Packstack create such "fake" external networks.

i am a bit confused as to when to use the provider network and when to tenant network option

Tenant networks if you want to allow users to create their own virtual network topology.

how does that affect the IP addresses you select for the VMs

VMs get their IP address from the subnet (i.e. address range) they are connected to. In the case of tenant networks, users can specify that address range.

For provider network option, does that mean that i can create virtual network inside Openstack using any IP addresses

It's the opposite. If you choose the provider option, you can't create virtual networks.

What is the recommendation for the sort of IP addresses I should be allocated to the virtual instances, i.e. should it be in the same subnet as the controller and compute node

For tenant networks, any range that the user sets up.

A provider network corresponds to a physical network or VLAN. The address range of the provider network is given by that physical network or VLAN. 10.0.0.11 and 10.0.0.31 might be connected to that same physical network, but in a production environment, most probably not (i.e. management network and provider network are separate. Often separate VLANs).

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thanks for your answers! I presume what you are saying is that with provider network, you can only create network based on real physical or VLAN IP addresses whereas with the tenant network, the users can make up their own IP addresses and create their own networks, is that right?

happy75 gravatar imagehappy75 ( 2020-01-07 17:33:32 -0500 )edit

Yes, that is right.

Bernd Bausch gravatar imageBernd Bausch ( 2020-01-07 23:55:28 -0500 )edit

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Asked: 2020-01-06 18:38:36 -0500

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Last updated: Jan 06