The Openvswitch installed on a Linux system provides the feature to configure multiple bridges. Multiple OVS bridges behave like independent local switches. This is the way OVS is providing switch virtualization. It is possible to chain multiple OVS bridges on one system. Chaining multiple bridges is used by Openstack neutron, when using the default networking […]
Openstack Neutron using VXLAN
The networking part of Openstack provides several models for the L2 networks to be used as L2 tenant broadcast domains. An overlay network can be used to separate the MAC addresses and „vlans“ of the tenant networks from the transport layer network. Openstack neutron in Havana supports two overlay network technologies, GRE and VXLAN. VXLAN […]
Sound generator using Gnuradio
Gnuradio is a powerful tool to process all sorts of signals using wave functions. This covers AM, FM, all sorts of modulation and much more. A simple starting point to play with Gnuradio is audio. It’s easy to built a tool to generate an audio tone, vary the frequency using a slider and output this […]
How to find namespaces in a Linux system
Namespaces in Linux are heavily used by many applications, e.g. LXC, Docker and Openstack. Question: How to find all existing namespaces in a Linux system? The answer is quite difficult, because it’s easy to hide a namespace or more exactly make it difficult to find them. Exploring the system In the basic/default setup Ubuntu 12.04 […]
Linux Network Namespaces – Background
Namespaces Managing network namespaces using the ip command is the prefered way. It is helpful to understand, what’s going on in the (kernel) background. If you create two network namespaces using ip netns add ns1 ip netns add ns2 you find to entries in the directory /var/run/netns/ ls -la /var/run/netns/ total 0 drwxr-xr-x 2 root […]
Opendaylight simple Version and Openvswitch
Openvswitch configuration After starting the Opendaylight controller we need a Openflow network device. Linux has one – the Openvswitch. So we use the Openvswitch. # # create a bridge with the name openflow # ovs-vsctl add-br openflow # # connect the bridge to the opendaylight openflow controller # ovs-vsctl set-controller openflow tcp:127.0.0.1:6633 After these to […]