This tutorial shows you how to explore features using
ovs-sandbox as a
simulated test environment. It’s assumed that you have an understanding of OVS
before going through this tutorial. Detail about OVN is covered in
ovn-architecture, but this tutorial lets you quickly see it in action.
For some general information about
ovs-sandbox, see the Open vSwitch
ovs-sandbox in the OVN repo includes OVN support by default. To start it,
you would simply need to run:
$ make sandbox
Running the sandbox does the following steps to the environment:
Creates a backup server for
OVN_Southbonddatabase. Sandbox launch screen provides the instructions on accessing the backup database. However access to the backup server is not required to go through the tutorial.
hardware_vtepdatabase as described in vtep(5).
GDB support is not required to go through the tutorial. See the “Using GDB” section of ovs-advanced in Open vSwitch documentation for more info. Additional flags exist for launching the debugger for the OVN programs:
--gdb-ovn-northd --gdb-ovn-controller --gdb-ovn-controller-vtep
Creating OVN Resources
Once you have
ovs-sandbox running with OVN enabled, you can start using OVN
utilities to create resources in OVN. As an example, we will create an
environment that has two logical switches connected by a logical router.
Create the first logical switch with one port:
$ ovn-nbctl ls-add sw0 $ ovn-nbctl lsp-add sw0 sw0-port1 $ ovn-nbctl lsp-set-addresses sw0-port1 "50:54:00:00:00:01 192.168.0.2"
Create the second logical switch with one port:
$ ovn-nbctl ls-add sw1 $ ovn-nbctl lsp-add sw1 sw1-port1 $ ovn-nbctl lsp-set-addresses sw1-port1 "50:54:00:00:00:03 18.104.22.168"
Create the logical router and attach both logical switches:
$ ovn-nbctl lr-add lr0 $ ovn-nbctl lrp-add lr0 lrp0 00:00:00:00:ff:01 192.168.0.1/24 $ ovn-nbctl lsp-add sw0 lrp0-attachment $ ovn-nbctl lsp-set-type lrp0-attachment router $ ovn-nbctl lsp-set-addresses lrp0-attachment 00:00:00:00:ff:01 $ ovn-nbctl lsp-set-options lrp0-attachment router-port=lrp0 $ ovn-nbctl lrp-add lr0 lrp1 00:00:00:00:ff:02 22.214.171.124/24 $ ovn-nbctl lsp-add sw1 lrp1-attachment $ ovn-nbctl lsp-set-type lrp1-attachment router $ ovn-nbctl lsp-set-addresses lrp1-attachment 00:00:00:00:ff:02 $ ovn-nbctl lsp-set-options lrp1-attachment router-port=lrp1
View a summary of OVN’s current logical configuration:
$ ovn-nbctl show switch 1396cf55-d176-4082-9a55-1c06cef626e4 (sw1) port lrp1-attachment addresses: ["00:00:00:00:ff:02"] port sw1-port1 addresses: ["50:54:00:00:00:03 126.96.36.199"] switch 2c9d6d03-09fc-4e32-8da6-305f129b0d53 (sw0) port lrp0-attachment addresses: ["00:00:00:00:ff:01"] port sw0-port1 addresses: ["50:54:00:00:00:01 192.168.0.2"] router f8377e8c-f75e-4fc8-8751-f3ea03c6dd98 (lr0) port lrp0 mac: "00:00:00:00:ff:01" networks: ["192.168.0.1/24"] port lrp1 mac: "00:00:00:00:ff:02" networks: ["188.8.131.52/24"]
tutorial directory of the OVS source tree includes a script
that runs all of the commands for you:
Once you have configured resources in OVN, try using
ovn-trace to see
how OVN would process a sample packet through its logical pipeline.
For example, we can trace an IP packet from
--minimal output shows each visible action performed on the packet,
The logical router will decrement the IP TTL field.
The logical router will change the source and destination MAC addresses to reflect the next hop.
The packet will be output to
$ ovn-trace --minimal sw0 'inport == "sw0-port1" \ > && eth.src == 50:54:00:00:00:01 && ip4.src == 192.168.0.2 \ > && eth.dst == 00:00:00:00:ff:01 && ip4.dst == 184.108.40.206 \ > && ip.ttl == 64' # ip,reg14=0x1,vlan_tci=0x0000,dl_src=50:54:00:00:00:01,dl_dst=00:00:00:00:ff:01,nw_src=192.168.0.2,nw_dst=220.127.116.11,nw_proto=0,nw_tos=0,nw_ecn=0,nw_ttl=64 ip.ttl--; eth.src = 00:00:00:00:ff:02; eth.dst = 50:54:00:00:00:03; output("sw1-port1");
ovn-trace utility can also provide much more detail on how the packet
would be processed through OVN’s logical pipeline, as well as correlate that
to OpenFlow flows programmed by
ovn-controller. See the ovn-trace(8)
man page for more detail.