This document provides an overview of Open vSwitch, including what it is, its main components, features, and how it can be used to build virtual network topologies. Open vSwitch is a software-defined networking switch that can be used to create virtual networks and handle network traffic between virtual machines and tunnels. It uses a distributed database, ovsdb-server, and a userspace daemon, ovs-vswitchd, to implement features like virtual switching, tunneling protocols, and OpenFlow support. Examples are provided for using Open vSwitch with KVM virtual machines and GRE tunnels to create virtual network topologies.

1. The Basic Introduction of
Open vSwitch
Te-Yen(Danny) Liu
Date : 2014/01/08

2. Agenda
 What is Virtual Switch?
 Virtual Network Topology using OVS
 What is Open vSwitch and Features?
 The Main Components
 Using OVS to build Network Topology
 Advanced Examples
 Demo
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3. What is Virtual Switch?
 In virtual network, virtual switch acts like an advanced edge
switch for VMs.
Hypervisor
vNIC
VIF
VM
VM
VM
Virtual
Network
(L2)
Virtual Switch
NIC as vSwitch’s
uplink port
Data Flow
Physical Switch
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4. Virtual Network Topology (1/2)
 An example of Virtual Network Topology in OpenStack
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5. Virtual Network Topology (2/2)
 Another example of Virtual Network Topology in OpenStack
 They use Open vSwitch as the solution to deal with the complication in virtual
newtork and multi-tenancy
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6. What is Open vSwitch?
 A software-based solution
 Resolve the problems of network separation and traffic
visibility, so the cloud users can be assigned VMs with
elastic and secure network configurations
 Flexible Controller in User-Space
 Fast Datapath in Kernel
 An implementation of Open Flow
Controller
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7. Open vSwitch Design
 Decision about how to process packet made in
userspace
 First packet of new flow goes to ovs-vswitchd,
following packets hit cached entry in kernel
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8. Features
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Visibility into inter-VM communication via NetFlow, sFlow(R), IPFIX, SPAN, RSPAN, and
GRE-tunneled mirrors
LACP (IEEE 802.1AX-2008)
Standard 802.1Q VLAN model with trunking
BFD and 802.1ag link monitoring
STP (IEEE 802.1D-1998)
Fine-grained QoS control
Support for HFSC qdisc
Per VM interface traffic policing
NIC bonding with source-MAC load balancing, active backup, and L4 hashing
OpenFlow protocol support (including many extensions for virtualization)
IPv6 support
Multiple tunneling protocols (GRE, VXLAN, IPsec, GRE and VXLAN over IPsec)
Remote configuration protocol with C and Python bindings
Kernel and user-space forwarding engine options
Multi-table forwarding pipeline with flow-caching engine
Forwarding layer abstraction to ease porting to new software and hardware platforms
The newest version is 2.0
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9. sFlow with OpenvSwitch
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10. The Main Components
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11. ovsdb-server
 Database that holds switch level configuration
 Custom database with nice properties:
 Log-based
 Speaks OVSDB management protocol(JSON-RPC)
to manager and ovs-vswitchd
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12. Example: Setup QoS
 There are two ways to do that:
 Interface Rate Limiting ( on Interface )
 For
instance:
– sudo ovs-vsctl set Interface eth1 ingress_policing_rate=10000
– sudo ovs-vsctl set Interface eth1 ingress_policing_burst=1000

Port QoS Policy ( on Port )
 For
–
–
–
–
–
–
–
–
–
instance:
sudo ovs-vsctl set port eth1 qos=@newqos
-- --id=@newqos create qos type=linux-htb
other-config:max-rate=200000000 queues=0=@q0,1=@q1
-- --id=@q0 create queue
other-config:min-rate=100000000
other-config:max-rate=100000000
-- --id=@q1 create queue
other-config:min-rate=50000000
other-config:max-rate=50000000
 Qos
can have more than 1 queue
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13. The example of QoS in OVS Database
 It is a GUI tool to see the tables in the ovsdb-server
 This case is about checking QoS setting
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14. ovs-vswitchd
 Core component in the system:
 Communicates with outside world using OpenFlow
 Communicates with ovsdb-server using management
protocol (OVSDB)
 Communicates with kernel module over netlink
 Communicates with the system through netdev abstract
interface
 Supports multiple independent datapaths (bridges)
 Implements mirroring, bonding, and VLANs through
modifications of the same flow table exposed
through OpenFlow
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15. OVS Kernel Module: openvswitch_mod.ko
 Handles switching and tunneling
 Exact-match cache of flows
 Designed to be fast and simple
 Packet comes in, if found, associated actions
executed and counters updated. Otherwise, sent to
userspace
 Does no flow expiration
 Knows nothing of OpenFlow
 Implements tunnels
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16. Using OVS to build Network Topology
 Physical Machine to Physical Machine
>ovs-vsctl add-br br0
>ovs-vsctl add-port br0 eth0
>ovs-vsctl add-port br0 eth1
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17. Using OVS to build Network Topology
 Virtual Machine to Virtual Machine
 Hypervisor is KVM
>ovs-vsctl add-br br0
>cat /etc/ovs-ifup
#!/bin/sh
switch= 'br0'
/sbin/ifconfig $1 0.0.0.0 up
ovs-vsctl add-port ${switch} $1
>cat /etc/ovs-ifup
#!/bin/sh
switch= 'br0'
/sbin/ifconfig $1 0.0.0.0 down
ovs-vsctl del-port ${switch} $1
>kvm -m 512 -net nic,macaddr=00:11:22:33:44:55-net
tap,script= /etc/ovs-ifup ,downscript= /etc/ovs-ifdown-drive
file = /path/to/disk-image ,boot=on
>kvm -m 512 -net nic,macaddr=11:22:33:44:55:66-net
tap,script= /etc/ovs-ifup ,downscript= /etc/ovs-ifdown-drive
file = /path/to/disk-image ,boot=on
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18. Using OVS to build Network Topology
 The profile of the virtual network
 Internal port is connected to IP Stack
 VMs connect with outside network via vport ( tap virtual
interface )
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19. Using OVS to build Network Topology
 Virtual Machine to Virtual Machine with GRE Tunnel
GRE Tunnel
GRE Tunnel
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20. Using OVS to build Network Topology
sudo ifconfig eth1 0
sudo ovs-vsctl add-br br1
sudo ovs-vsctl add-br br2
sudo ovs-vsctl add-port br1 eth0
sudo ifconfig br1 192.168.1.155 netmask 255.255.255.0
sudo ifconfig br2 10.1.1.1 netmask 255.255.255.0
sudo ovs-vsctl add-port br2 gre0 -- set interface gre0 type=gre options:remote_ip=192.168.1.152
sudo ifconfig eth1 0
sudo ovs-vsctl add-br br1
sudo ovs-vsctl add-br br2
sudo ovs-vsctl add-port br1 eth0
sudo ifconfig br1 192.168.1.152 netmask 255.255.255.0
sudo ifconfig br2 10.1.1.2 netmask 255.255.255.0
sudo ovs-vsctl add-port br2 gre0 -- set interface gre0 type=gre options:remote_ip=192.168.1.155
sudo vi /etc/ovs-ifup
#!/bin/sh
switch='br2'
/sbin/ifconfig $1 0.0.0.0 up
ovs-vsctl add-port ${switch} $1
sudo vi /etc/ovs-ifdown
#!/bin/sh
switch=’br2’
/sbin/ifconfig $1 0.0.0.0 down
ovs-vsctl del-port ${switch} $1
sudo chmod +x /etc/ovs-ifup /etc/ovs-ifdown
sudo kvm -m 512 -net nic,macaddr=11:22:33:44:55:66 -net tap,script=/etc/ovs-ifup,downscript=/etc/ovs-ifdown -cdrom
/home/brent/images/ubuntu-12.04-desktop-i386.iso &
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21. Using OVS to build Network Topology
 Bridge to Bridge
 They need a patch port to communicate with each other
ovs-vsctl add-br br0
ovs-vsctl add-br br1
ovs-vsctl add-port br0 patch-to-br1
ovs-vsctl set interface patch-to-br1type=patch
ovs-vsctl set interface patch-to-br1 options:peer=patch-to-br0
ovs-vsctl add-port br1 patch-to-br0
ovs-vsctl set nterface patch-to-br0type=patch
ovs-vsctl set interface patch-to-br0 options:peer=patch-to-br1
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22. Demo Topology
 The host: OVS1 and OVS2 communicate with each other by GRE Tunnel
 The host: KVM will provision a VM guest and communicates with OVS1
and OVS2
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23. OVS with GRE Tunnel Demo (1/2)
 OVS1 and OVS2 communicate with each other by GRE Tunnel
sudo ovs-vsctl add-br br0
sudo ovs-vsctl add-br br1
sudo ovs-vsctl add-port br0 eth0
sudo ifconfig eth0 0
sudo ifconfig br0 192.168.1.10 netmask 255.255.255.0
sudo route add default gw 192.168.1.1 br0
sudo ifconfig br1 10.1.2.10 netmask 255.255.255.0
sudo ovs-vsctl add-port br1 gre1 -- set interface gre1 type=gre
options:remote_ip=192.168.1.11
sudo ovs-vsctl add-br br0
sudo ovs-vsctl add-br br1
sudo ovs-vsctl add-port br0 eth0
sudo ifconfig eth0 0
sudo ifconfig br0 192.168.1.11 netmask 255.255.255.0
sudo route add default gw 192.168.1.1 br0
sudo ifconfig br1 10.1.2.11 netmask 255.255.255.0
sudo ovs-vsctl add-port br1 gre1 -- set interface gre1 type=gre
options:remote_ip=192.168.1.10
IP: 192.168.1.10
Default GW: 192.168.1.1
br0
IP: 10.1.2.10
br1
gre1 Remote IP:
192.168.1.11
eth0
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24. OVS with GRE Tunnel Demo (2/2)
 OVS1 and OVS2 in bare metal mode to communicate with each
other by GRE Tunnel
sudo ovs-vsctl add-br br-int
sudo ifconfig eth0 192.168.1.10 netmask 255.255.255.0
sudo route add default gw 192.168.1.1 eth0
sudo ovs-vsctl add-port br-int mgmt0 -- set interface mgmt0
type=internal
sudo ifconfig mgmt0 10.1.2.10 netmask 255.255.255.0
sudo ovs-vsctl add-port br-int gre1 -- set interface gre1
type=gre options:remote_ip=192.168.1.11
br0
mgmt0
sudo ovs-vsctl add-br br-int
sudo ifconfig eth0 192.168.1.11 netmask 255.255.255.0
sudo route add default gw 192.168.1.1 eth0
sudo ovs-vsctl add-port br-int mgmt0 -- set interface mgmt0
type=internal
sudo ifconfig mgmt0 10.1.2.11 netmask 255.255.255.0
sudo ovs-vsctl add-port br-int gre1 -- set interface gre1
type=gre options:remote_ip=192.168.1.10
gre1
Remote IP:
192.168.1.11
IP: 10.1.2.10
eth0
IP: 192.168.1.10
Default GW: 192.168.1.1
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25. OVS with KVM and guest VM Demo
 The host: KVM will provision a VM guest and communicates with OVS1 and
OVS2
IP: 10.1.2.10 IP: 10.1.2.11
VM1
VM2
tap0
br0
tap1
IP: 192.168.1.20
Default GW: 192.168.1.1
eth0
sudo ovs-vsctl add-br br0
sudo ovs-vsctl add-port br0 eth0
sudo ovs-vsctl list port
sudo ifconfig eth0 0
sudo ifconfig br0 192.168.1.20 netmask 255.255.255.0
sudo route add default gw 192.168.1.1 br0
sudo kvm -m 512 -hda /home/liudanny/kvm_lab/linux-core-4.7.7-openvswitch-1.11.0_guagga-0.99.22.4.img -net
nic,macaddr=00:11:22:33:44:55 -net tap,script=/etc/ovs-ifup,downscript=/etc/ovs-ifdown
sudo kvm -m 512 -hda /home/liudanny/kvm_lab/linux-core-4.7.7-openvswitch-1.11.0_guagga-0.99.22.4.img -net
nic,macaddr=11:22:33:44:55:66 -net tap,script=/etc/ovs-ifup,downscript=/etc/ovs-ifdown
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26. Q&A
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27. Reference
 http://blog.scottlowe.org/2013/05/07/using-gre-tunnels-with





open-vswitch/
http://lamoop.com/post/2013-11-18/40060149263
http://www.youtube.com/watch?v=rYW7kQRyUvA
http://networkstatic.net/open-vswitch-gre-tunnel-configuration/
http://networkstatic.net/configuring-vxlan-and-gre-tunnels-onopenvswitch/
http://openvswitch.org/ovs-vswitchd.conf.db.5.pdf
http://openvswitch.org/
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