Chapter 5. Midolman

Midolman (the MidoNet Agent) is the daemon that runs on all hosts where traffic enters and leaves MidoNet.

It instructs the Open vSwitch kernel module on how to handle network traffic (what modifications to apply to packets and where to tunnel them to).

Midolman requires a Linux kernel that has the Open vSwitch kernel module installed and a Java 7 runtime in userspace (we recommend using OpenJDK 7).

Midolman is designed to work with Open vSwitch kernel module version 1.10.2 or later. If you need to update the kernel module, you may be able to find a later version of the module in the cloud software repositories for your distribution.

 Recommended installation nodes

Where Midolman is being used to network virtual machines, you should generally install it on the host machines alongside the hypervisor.

If you are using it with the Border Gateway Protocol (BGP), you should install it on nodes with very few hops to the BGP peer (ideally one). Where there is north-south traffic for MidoNet, you should install Midolman on machines with sufficient bandwidth and proximity to the up-links to handle the traffic.

 Configuration guidelines

Midolman requires that you specify the ZooKeeper and Cassandra server IP addresses in the Midolman configuration file.

You can configure Midolman to detect node failures faster by reducing the ZooKeeper session timeout and session grace time values. However, this will also reduce the window of time after a transient outage that the system can recover from, instead of being treated as a node failure. Increasing these timeout values has the opposite effect. We don’t recommend making changes to the default timeout values, except possibly the session_gracetime setting value.

 Network accessibility considerations

MidoNet Agent hosts in the same tunnel zone must have IP connectivity to each other.

They also require TCP connectivity to the ZooKeeper and Cassandra servers (the default TCP port numbers are 2181 for ZooKeeper and 9042 for Cassandra).

MidoNet Agents use the Domain Name System (DNS) to convert between hostnames and underlay network addresses. Verify that each server on which you install the MidoNet Agent has a resolvable hostname.

Questions? Discuss on Mailing Lists or Chat.
Found an error? Report a bug.