Ask Your Question

justinsb's profile - activity

2013-10-23 21:54:28 -0600 received badge  Student (source)
2013-05-16 06:31:34 -0600 received badge  Famous Question (source)
2013-05-15 17:52:59 -0600 commented answer Why do people believe the FlatManager is a bad option for networking?

With config-drive it isn't so bad, though it needs cloud-init. I think (with everyone's help) I've distilled the essence of my question to be: what is the problem with flat networking & why is nova-network in the network path for outgoing network connections from VM. I'll edit the question...

2013-05-15 17:08:02 -0600 received badge  Notable Question (source)
2013-05-15 15:58:41 -0600 commented question Why do people believe the FlatManager is a bad option for networking?

@darragh-oreilly: Looks like you're right (I re-read the code). I guess I'm asking why nova-network is in the path for outgoing network connections from a VM, vs just using the network's existing router (which presumably is just as capable of doing NAT).

2013-05-15 14:57:10 -0600 commented answer Why do people believe the FlatManager is a bad option for networking?

1) I think you'd use Layer 2 at the rack level, and Layer 3 switches to join the racks (?). 2) Fair point, but I think bandwidth limits and security rules etc could still be applied at the compute node. 3) I don't think that's true; nova assigns IP addresses even using FlatManager.

2013-05-15 14:54:00 -0600 commented answer Why do people believe the FlatManager is a bad option for networking?

Thanks Lorin. Nova still assigns IPs with FlatManager, but injecting them does need e.g. config-drive. My understanding is that this is now better supported by cloud-init. I'm trying to figure out the underlying technical limitations though, before maybe attacking those implementation issues!

2013-05-15 14:53:08 -0600 commented question Why do people believe the FlatManager is a bad option for networking?

darragh-oreilly: I'm pretty sure it doesn't need to be used (the FlatManager class seems to be used in both the compute node and nova-network). I've used a normal network gateway in the past, instead of nova-network. (I think you'd need nova-network for floating-ips, unless you played ARP tricks)

2013-05-15 13:13:41 -0600 received badge  Popular Question (source)
2013-05-15 08:54:43 -0600 received badge  Editor (source)
2013-05-15 08:54:03 -0600 asked a question Why do people believe the FlatManager is a bad option for networking?

Can someone explain why FlatManager is a bad networking option? In discussions of OpenStack's networking options, it is usually dismissed out of hand, but I can't find a good justification.

FlatManager has several advantages: no nova-network SPOF or overhead, easier to integrate with existing networks; and simplicity. I've had great experiences using FlatManager at small scale (apart from that it sometimes feels like I'm the only user!)

I presume there are disadvantages that outweigh the advantages, but I can't find what those are!

Let's ignore the lack of support for floating IPs: they will probably still need a nova-network service; right now nova-network isn't enabled with FlatManager; but I believe that it could be enabled with FlatManager and handle only floating-ip traffic. (Unless of course floating IPs + FlatManager is actually impossible!)