Namespaces 09 - Connecting two network namespaces (ns1, ns2) - with two veth pairs and a distributed OVS switch (openvswitch)

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 [1] NET namespace - Connecting two network namespaces (ns1, ns2) - with two veth pairs and
                     a distributed OVS switch (openvswitch)
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     +------------------+                 +-------------------------------+                 +------------------+
     | ns1        veth1 |======cable======| veth1-ovs   ovs0    veth2-ovs |======cable======| veth2        ns2 |
     +------------------+                 +-------------------------------+                 +------------------+
       namespace "ns1"                        host system (openvswitch)                        namespace "ns2"

    The first  Ethernet cable (between namespace "ns1" and the OVS switch "ovs0"): veth1====veth1-ovs
    The second Ethernet cable (between namespace "ns2" and the OVS switch "ovs0"): veth2====veth2-ovs

    These test scenarios use RedHat Linux 7.3, which does carry the kernel module for Openvswitch, but
    no longer carries the user tools that administer openvswitch (ovs-vsctl). Those user tools are
    carried in other Redhat products such as Red Hat Openstack Platform and the like. At this point
    there is nothing for it but to install Openvswitch from source, see [1.0.X].

    [1.0.1] Installing the distributed switch Openvswitch successfully needs the tools to compile it and
            the libraries that Openvswitch uses.
    ----------------------------------------------------------------------------------------------------------------
    # yum install gcc make python-devel openssl-devel kernel-devel graphviz kernel-debug-devel autoconf automake \
      rpm-build redhat-rpm-config libtool checkpolicy selinux-policy-devel python-six
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    [1.0.2] - Create a directory to build the RPM package from source in, and download the current source package
              for Openvswitch.
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    # mkdir -p /root/rpmbuild/SOURCES
    # cd /root/rpmbuild/SOURCES
    # wget http://openvswitch.org/releases/openvswitch-2.6.1.tar.gz
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    [1.0.3] - Unpack the source package, compile it and build the RPM package
              The RPM packages for Openvswitch appear in "/root/rpmbuild/RPMS/x86_64/"
    ----------------------------------------------------------------------------------------------------------------
    # cd /root/rpmbuild/SOURCES/
    # tar -xvf ./openvswitch-2.6.1.tar.gz
    # sed 's/openvswitch-kmod, //g' openvswitch-2.6.1/rhel/openvswitch.spec > openvswitch-2.6.1/rhel/openvswitch_no_kmod.spec
    # rpmbuild -bb --nocheck openvswitch-2.6.1/rhel/openvswitch_no_kmod.spec
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    [1.0.4] - Install the RPM package with Openvswitch
    ----------------------------------------------------------------------------------------------------------------
    # cd /root/rpmbuild/RPMS/x86_64/
    # yum localinstall ./openvswitch-2.6.1-1.x86_64.rpm
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    [1.1] - Remove the network namespaces "ns1" and "ns2" (if they exist).
    [1.2] - Create two network (NET) namespaces, "ns1" and "ns2".
    ----------------------------------------------------------------------------------------------------------------
    [1.1]# ip netns del ns1 &>/dev/null
    [1.1]# ip netns del ns2 &>/dev/null
    [1.2]# ip netns add ns1
    [1.2]# ip netns add ns2
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    [1.3] - On the host system, start Openvswitch and
    [1.3] - create a distributed (openvswitch) Ethernet switch/bridge named "ovs0".
    ----------------------------------------------------------------------------------------------------------------
    [1.3]# /etc/init.d/openvswitch start
    [1.3]# ovs-vsctl add-br ovs0
    ----------------------------------------------------------------------------------------------------------------

    [1.4]TERM1 - In network namespace "ns1", exec the command "bash".
    [1.5]TERM2 - In network namespace "ns2", exec the command "bash".
    ----------------------------------------------------------------------------------------------------------------
    [1.4]TERM1# ip netns exec ns1 bash
    [1.5]TERM2# ip netns exec ns2 bash
    ----------------------------------------------------------------------------------------------------------------

    [1.6]  - Create a pair of virtual Ethernet devices, which stand for a network cable with two RJ45
             plugs, then put one end (veth1) into namespace "ns1" and the other end
             (veth1-ovs) into the distributed Ethernet switch "ovs0".
    [1.7]  - Put the virtual Ethernet adapter "veth1" into network namespace "ns1".
    [1.8]  - Connect the virtual Ethernet adapter "veth1-ovs" to the distributed Ethernet switch "ovs0".

    [1.9]  - Create a pair of virtual Ethernet devices, which stand for a network cable with two RJ45
             plugs, then put one end (veth2) into namespace "ns2" and the other end
             (veth2-ovs) into the distributed Ethernet switch "ovs0".
    [1.10] - Put the virtual Ethernet adapter "veth2" into network namespace "ns2".
    [1.11] - Connect the virtual Ethernet adapter "veth2-ovs" to the distributed Ethernet switch "ovs0".
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    [1.6] # ip link add veth1 type veth peer name veth1-ovs
    [1.7] # ip link set veth1 netns ns1
    [1.8] # ovs-vsctl add-port ovs0 veth1-ovs

    [1.9] # ip link add veth2 type veth peer name veth2-ovs
    [1.10]# ip link set veth2 netns ns2
    [1.11]# ovs-vsctl add-port ovs0 veth2-ovs
    ----------------------------------------------------------------------------------------------------------------

    [1.12] - Bring the network adapter "veth1" up in namespace "ns1" and give it the address "10.0.0.1".
    [1.13] - Bring the network adapter/port "veth1-ovs" up on the distributed switch "ovs0".

    [1.14] - Bring the network adapter "veth2" up in namespace "ns2" and give it the address "10.0.0.2".
    [1.15] - Bring the network adapter/port "veth2-ovs" up on the distributed switch "ovs0".

    [1.16] - From network namespace "ns1", test that namespace "ns2" answers.
    [1.17] - From network namespace "ns2", test that namespace "ns1" answers.
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    [1.12]# ip netns exec ns1 ifconfig veth1 10.0.0.1/24 up
    [1.13]# ip link set dev veth1-ovs up

    [1.14]# ip netns exec ns2 ifconfig veth2 10.0.0.2/24 up
    [1.15]# ip link set dev veth2-ovs up

    [1.16]# ip netns exec ns1 ping 10.0.0.2
    [1.17]# ip netns exec ns2 ping 10.0.0.1
    ----------------------------------------------------------------------------------------------------------------

$ # systemctl start openvswitch
$ # ovs-vsctl --may-exist add-br ovs0