Easiest Way to Setup Keyboard

Install gnome-initial-setup package:

# pacman -Sy gnome-initial-setup

And restart Arch Linux.

Now, it should pop out a user interface to setup default language and keyboard map.

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How to connect OpenFlow switches to multiple controllers (Mininet)

Original post is here.

#!/usr/bin/python

from mininet.net import Mininet
from mininet.node import Controller, RemoteController
from mininet.cli import CLI
from mininet.log import setLogLevel, info

def myNet():


    #OpenDayLight controller
    ODL_CONTROLLER_IP='10.0.0.4'

    #Floodlight controller
    FL_CONTROLLER_IP='10.0.0.5'

    net = Mininet( topo=None, build=False)

    # Create nodes
    h1 = net.addHost( 'h1', mac='01:00:00:00:01:00', ip='192.168.0.1/24' )
    h2 = net.addHost( 'h2', mac='01:00:00:00:02:00', ip='192.168.0.2/24' )

    # Create switches
    s1 = net.addSwitch( 's1', listenPort=6634, mac='00:00:00:00:00:01' )
    s2 = net.addSwitch( 's2', listenPort=6634, mac='00:00:00:00:00:02' )

    print "*** Creating links"
    net.addLink(h1, s1, )
    net.addLink(h2, s2, )   
    net.addLink(s1, s2, )  

    # Add Controllers
    odl_ctrl = net.addController( 'c0', controller=RemoteController, ip=ODL_CONTROLLER_IP, port=6633)

    fl_ctrl = net.addController( 'c1', controller=RemoteController, ip=FL_CONTROLLER_IP, port=6633)


    net.build()

    # Connect each switch to a different controller
    s1.start( [odl_ctrl] )
    s2.start( [fl_ctrl] )

    s1.cmdPrint('ovs-vsctl show')

    CLI( net )
    net.stop()

if __name__ == '__main__':
    setLogLevel( 'info' )
    myNet()

Openvswitch Module

If you’re getting kernel module installation errors, probably the module is not compiled for the current kernel or its dependencies are not loaded.

# insmod datapath/linux/openvswitch.ko

Error:

datapath/linux/openvswitch.ko: Unknown symbol in module

By using the command modinfo, you can take clues about the module, such as its dependencies and kernel version that was used to compile.

If the problem is dependencies, instead of using insmod to install openvswitch.ko module, you can first type the command in the OVS root directory (after compiling):

# make install

This will install all compiled modules in the Linux system. Then, type:

# modprobe openvswitch

The command should automatically load openvswitch module and its dependencies.

NETIF_F_NETNS_LOCAL

Original post here.

NETIF_F_NETNS_LOCAL a flag to indicate
a network device is local to a single network namespace and
should never be moved.  Useful for pseudo devices that we
need an instance in each network namespace (like the loopback
device) and for any device we find that cannot handle multiple
network namespaces so we may trap them in the initial network
namespace.

 

Linux Kernel Network Namespace (NETNS)

Original post here.

“So what are network namespaces? Generally speaking, an installation of Linux shares a single set of network interfaces and routing table entries. You can modify the routing table entries using policy routing (here’s an introduction I wrote and here’s a write-up on a potential use case for policy routing), but that doesn’t fundamentally change the fact that the set of network interfaces and routing tables/entries are shared across the entire OS. Network namespaces change that fundamental assumption. With network namespaces, you can have different and separate instances of network interfaces and routing tables that operate independent of each other.”