Building a router with Open vSwitch
As part of my work in OpenDaylight, we are looking at creating a router using Open vSwitch... Why? Well OpenStack requires some limited L3 capabilities and we think that we can handle those in a distributed router.
Test Topology
My test topology looks like this:

We have a host in an external network 172.16.1.0/24, one host in an internal network 10.10.10.0/24 and two hosts in another internal network 10.10.20.0/24.
As such, The hosts in the 10.x.x.x range should be able to speak to each other, but should not be able to speak to external hosts.
The host 10.10.10.2 has a floating IP of 172.16.1.10 and should be reachable on this address from the external 172.16.1.0/24 network. To do this, we'll use DNAT for traffic from 172.16.1.2 -> 172.16.1.10 and SNAT for traffic back from 10.10.10.2 -> 172.16.1.2
If you'd like to recreate this topology you can checkout the OpenDaylight OVSDB project source on GitHub and:
vagrant up mininet
vagrant ssh mininet
cd /vagrant/resources/mininet
sudo mn --custom Continue reading

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