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I am trying to set up devstack in a test environment. I eventually want to get to multi-node to show scaling, but for now I'd be glad if I could get it going within a single VM. From what I can see, the critical bit is getting the local.conf setup correctly, but the documentation for it seems to be confusing or lacking. I do see this bit on the single-node page:

Run DevStack

Now to configure stack.sh. DevStack includes a sample in devstack/samples/local.conf. Create local.conf as shown below to do the following:

  • Set FLOATING_RANGE to a range not used on the local network, i.e. 192.168.1.224/27. This configures IP addresses ending in 225-254 to be used as floating IPs.
  • Set FIXED_RANGE and FIXED_NETWORK_SIZE to configure the internal address space used by the instances.
  • Set FLAT_INTERFACE to the Ethernet interface that connects the host to your local network. This is the interface that should be configured with the static IP address mentioned above.

OK so first, how does "192.168.1.224/27" translate to "225-254"? Is this a typo that should say "225-251"?

Is "FLOATING_RANGE" the range of the VM's that are spun up and "FIXED_RANGE" the range of the host machines? I'm guess - this isn't clear at all. Which ones show up from outside the systems? How are these used? What is FIXED_NETWORK_SIZE?

The bigger question is, how can I set up DevStack in an environment where I don't have access a large IP address range? Are the FLOATING_RANGE numbers just IP's internally and they don't need to be able to be reached directly from the outside? Can I just use some non-public IP's that don't fit without our network topology, or do they need to be an explicit hole in our network IP range (i.e. there exists a default gateway, etc.)?

Jared
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  • Why are people voting to close this? And doing so without leaving comments seems cowardly. How do you view this as a not relevant question? I'd like to refine it if possible. – Jared Aug 27 '14 at 13:29

2 Answers2

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So digging into the code myself, I've found that the notation used is CIDR network notation. Thus the 27 refers to 27 "1" bits that form the netmask.

I'm still working on figuring out what the FIXED_NETWORK_SIZE corresponds to (is this number of physical machines?). I'll edit if/when I figure this out.

Jared
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4th octet of 192.168.1.224/27 is 111[00000]<-from 27 to 32 therefore the fixed subnet range is from 11100001 to 11111110 (excludes [00000] and [11111])

FIXED_RANGE is the range of VMs and you don't have to set FIXED_NETWORK_SIZE. FLOATING_RANGE is for external (public) network.

[ external network (FLOATING_RANGE) ] - [ gateway ] - [ internal network (FIXED_RANGE) ] - [VMs]

Masashi Teruya
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