Archives For networking

This is what our Cloud looks like in the CloudStack Dashboard. Pretty powerful 🙂

These are the boxes the hardware was in.

This image is taken in our lab while testing CloudStack.

Very handy: a tray for spares in your rack!


This is the front: 6 compute nodes, 2 management servers and 2 Linux routers that manage all traffic. We also have 2 big storage servers that you cannot see on this image.

This is how the back of the rack in the data center looks like after we’ve built everything in.

Close up of power management and storage network.

And the final image shows the serial, public, and manage networks.

We’ve labelled and documented every cable and used a separate color for each connection type (i.e. mgt network, storage network, uplinks, cross links, serial connections, etc).

Networking in CloudStack 3.0 is awesome; the Virtual Router provides many cool features like LoadBalancing, PortForwarding, (s)NAT, DHCP, VPN and so on. When a new network is created and being used, a Virtual Router is automatically launched to support these features. Since the Virtual Router is a Single Point of Failure, you should turn on the HA (High Available) option; which actually addes a 2nd Virtual Router on each network. While this is pretty cool, it makes the number of System VM’s go up and when you don’t need them it’s kind of wasting resources.

For example, when I was creating a network for the web servers to talk privately to the database, I didn’t need a Virtual Router. All I want is them to be able to do networking to each other and that is all. When using the default settings, a Virtual Router is launched anyway.

So how to tell CloudStack you don’t need a Virtual Router? Well, this is done through Service Offerings. You find this option on the menu at the left, it’s the last option. Select Network Offerings and a list is displayed.

Click Add Network Offering at the right and fill in the form. When you do not select any service, you’ll create a Network Offering for which CloudStack does not spin off Virtual Routers.

Now, when you create a new Guest Network, make sure to select the Network Offering you just created. This will make sure your new Guest network will have no Virtual Router launched when in use 🙂

Update: I’ve written another blog with more details on how to use this network. Also have a look at the comments in both blogs for some examples and idea’s. Feel free to ask me any questions you have below!

Adding a route manually can be necessary sometimes. When on Linux, I know the command by head:

sudo route add -net gw

On the Mac the command is similar, but a bit different 🙂 Just as a note to myself and anyone else interested:

sudo route -n add -net

This sets up a route to the net through gateway First one on Linux, second one on Mac OSX.