SDNDS.TW Mininet

meetup#3
Mininet
shanyu@sdnds-tw

About me
❖Shanyua.k.a.Leader31
❖碩二研究生
❖NCTU Wireless Internet Lab
❖Logdown: http://shanyu.logdown.com
❖Github: https://github.com/evelyn3648/MininetTopo

Outline
❖Introduction to Mininet
❖Mininetbasic operation
❖MininetUse Scenario

Mininetversion
❖Download: http://mininet.org/download/
❖Default version: 2.1.0
❖Newest version: 2.2.0b1
❖Improved OpenFlow1.3 support
❖Mininet2.1.0 support OpenFlow1.3
❖http://www.sdnlab.com/3460
❖ovs-vsctlset bridge XX protocols=OpenFlow13
❖Upgrade OVS
❖http://www.sdnlab.com/3679
Modify mininet/mininet/node.py

What Is Mininet?
❖工欲善其事必先利其器
❖Mininetis a network emulator
❖“Mininetcreates a realistic virtual network, running real kernel, switch and application code, on a single machine (VM, cloud or native)” –mininet.org
❖Mininetuses lightweight virtualization to make a single system look like a complete network

Testbed
Platform
Advantages
Disadvantages
Hardware Testbed
reality
accurate: "ground truth"
expensive
shared resource?
hard to reconfigure
hard to change
Simulator
inexpensive, flexible
detailed (or abstract!)
virtual time (can be
"faster" than reality)
may require app changes
might not run OS code
may not be "believable"
may be slow/non-interactive
Emulator
inexpensive, flexible
real code
reasonably accurate
fast/interactive usage
slower than hardware
experiments may not fit
possible inaccuracy from
multiplexing

A simple network topology
S1
h1
h2
firefox
httpd

Lightweight Virtualization(Network Namespaces and Virtual Ethernet pairs)
virtual Ethernet pairs
Network namespace: logically another copy of the network stack, with its own routes, firewall rules, and network devices
VirtualEthernetpairs:A vethpair is a pair of virtual interfaces that act as a
straight through connection.

Lightweight Virtualization & Performance modeling withLinux
Network component or
property
Modeling mechanism
Configuration
command(s)
Hosts
Processesin network
namespaces
ipnetns
Links
Virtual Ethernetpairs
iplink
Switches
Software switches (OVS)
ovs-vsctl
Controllers
Processes
controller
Link performance
Traffic Control (Bandwidth,Delay,loss, max queue)
tc
CPU performance
CPU Control Groups
cg{create,set,delete,
classify}

Create it with Linux command
sudobash
# Create host namespaces
ipnetnsadd h1
ipnetnsadd h2
# Create switch
ovs-vsctladd-brs1
# Create links
iplink add h1-eth0 type vethpeer name s1-eth1
iplink add h2-eth0 type vethpeer name s1-eth2
iplink show
# Move host ports into namespaces
iplink set h1-eth0 netnsh1
iplink set h2-eth0 netnsh2
ipnetnsexec h1 iplink show
ipnetnsexec h2 iplink show
# Connect switch ports to OVS
ovs-vsctladd-port s1 s1-eth1
ovs-vsctladd-port s1 s1-eth2
ovs-vsctlshow
# Set up OpenFlowcontroller
ovs-vsctlset-controller s1 tcp:127.0.0.1
ovs-controller ptcp: &
ovs-vsctlshow
# Configure network
ipnetnsexec h1 ifconfigh1-eth0 10.0.0.1
ipnetnsexec h1 ifconfiglo up
ipnetnsexec h2 ifconfigh2-eth0 10.0.0.2
ipnetnsexec h1 ifconfiglo up
ifconfigs1-eth1 up
ifconfigs1-eth2 up
# Test network
ipnetnsexec h1 ping -c1 10.0.0.2
Controller
S1
h1
h2
將virtual interface/link
綁訂到對應host的namespace
建立veth連線和
兩端的virualinterface

Classes in MininetTopo
mininet.topo.Topo
mininet.topo.LinearTopo
mininet.topo.SingleSwitchTopo
mininet.topo.SingleSwitchReversedTopo
mininet.topolib.TreeTopo
mininet.topolib.TorusTopo
linear,n: 每個switch (s1-s2-s3…-sn)上各有一個host(h1,h2…,hn)
single,k: 一台switch上面有k個host (h1…,hk) [default topology (h1-s1-h2)]
reverse,k:一台switch上面有k個host (hk…,h1)
tree,depth=d,fanout=f: 一顆深度為d，每個node有f個child的tree
2-D Torus topology: this topology has LOOPS
Default
NEW

Classes in MininetNode
mininet.node
.Node
mininet.node
.Controller
mininet.node
.Host
mininet.node.
Switch
mininet.node
.Nox
mininet.node.
OVSController
mininet.node.
RemoteController
mininet.node.
CPULimitedHost
mininet.node. IVSSwitch
mininet.node.
OVSLegacyKernelSwitch
mininet.node
.OVSSwitch
mininet.node.
UserSwitch
mininet.node.
OVSBridge
mininet.node
.RYU
mininet.node
.NAT
mininet.nodelib. LinuxBridge
Default
NEW

Classes in MininetLink
mininet.link.Link
mininet.link.Intf
mininet.link
.TCLink
mininet.link
.TCIntf
Basicinterface object that can configure itself
A basic link is just a vethpair

Mininetcommand line
❖$sudomn
連線到外部controller
$sudomn–controller=remote,ip=<ip>,port=<port>
Defaultip: 127.0.0.1
Defaultport: 6633 (IANA define OpenFlowport:6653)

Mininetbasic Command
❖顯示nodes (controllers, hosts, switches) 列表
❖mininet> nodes
❖顯示links 列表
❖mininet> net
❖顯示nodes 詳細資訊
❖mininet> dump
❖離開CLI
❖mininet> exit
❖mininet> <ctrl>+D
❖清除Mininet
❖sudomn–c

Virtual Switch / Datapath管理
❖所有virtual switches 狀態
❖mininet> dpctlshow
❖所有switches 支援的OpenFlowversions
❖mininet> dpctl–version
❖註: OF1.0 = 0x01, OF1.3 = 0x04
❖所有switches 上所有flow entries
❖mininet> dpctldump-flows
❖所有switches 上ports 的流量統計
❖mininet> dpctldump-ports

Custom network topology
❖Mininetscript withpython API
❖Low-level API: Node and Links
❖Mid-level API: Network Object
❖High-level API: Topology templates
❖sudomn–custom ./<XXX.py> --topo XXX
❖api.mininet.org
❖docs.mininet.org
❖Introduction to Mininet
❖Some examples in mininet/example
Controller
S1
h1
h2

Low-level API: Node and Links
h1 = Host( 'h1' )
h2 = Host( 'h2' )
s1 = OVSSwitch( 's1', inNamespace=False )
c0 = Controller( 'c0', inNamespace=False )
Link( h1, s1 )
Link( h2, s1 )
h1.setIP( '10.1/8' )
h2.setIP( '10.2/8' )
c0.start()
s1.start( [ c0 ] )
s1.stop()
c0.stop()
Controller
S1
h1
h2

Mid-level API: Network object
net = Mininet()
h1 = net.addHost( 'h1' )
h2 = net.addHost( 'h2' )
s1 = net.addSwitch( 's1' )
c0 = net.addController( 'c0' )
net.addLink( h1, s1 )
net.addLink( h2, s1 )
net.start()
CLI( net )
net.stop()
Controller
S1
h1
h2

High-level API: Topology templates
class SingleSwitchTopo( Topo ):
"Single switch connected to k hosts.“
defbuild( self, k=2, **opts ):
"k: number of hosts"
self.k= k
switch = self.addSwitch( 's1' )
for h in irange( 1, k ):
host = self.addHost( 'h%s' % h )
self.addLink( host, switch )
net = Mininet( topo=SingleSwitchTopo( 2 ) )
net.start()
CLI( net )
net.stop()
Controller
S1
h1
h2

Mininethosts connect to internet
❖Method1: create node (NAT)
❖through hostOS
❖Iptablescommand
❖MASQUERADE, ip_forward
❖Method2: via OVS command
❖ovs-vsctladd-port s1 eth0
❖Host OS also want to access internet
❖http://rascov.logdown.com/posts/231057-bridge-mininet-to- the-internet

Mininetmulti hosts want to run same service
❖Mininethosts share the same file system
❖Problem: multi hosts can’t run same daemon (snmpd, httpd) at the same time
❖service XXX start/restart/stop
❖Web Server
❖python -m SimpleHTTPServer80 &
❖Snmp
❖/usr/sbin/snmpd-LS n d -Lf /dev/null -p /var/run/snmpd.pid
❖Problem: get same CPU usage form all hosts

Multisubnet
❖S1beaRouter (gateway)
❖Create a gateway host
❖Modify routing table & ip_forwardon gateway host
❖http://shanyu.logdown.com/posts/223708-mininet-with-multi-subnet
❖Mininetadd linuxrouternode in upcoming version
❖https://github.com/mininet/mininet/blob/65e33fed9b1d583a90c9dd09e6fd64e5354b377c/examples/linuxrouter.py
❖Controller act ARP proxy (OpenDaylight)
❖Using flow rule let switch be a gateway router
❖http://hwchiu.logdown.com/posts/203260-mininet-and-network-subnet
10.0.0.0
/24
10.1.0.0
/24
10.2.0.0
/24
S1

References
❖Tutorial at SIGCOMM 2014
❖https://github.com/mininet/mininet/wiki/Teaching-and- Learning-with-Mininet
❖SDNLAB
❖http://www.sdnlab.com/
❖Hwchiublog
❖http://hwchiu.logdown.com/
❖Rascovblog
❖http://rascov.logdown.com/

SDNDS.TW Mininet

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