Getting to know OpenFlow
Nick Rutherford – Mariano Vallés
{nicholas,mariano}@ac.upc.edu
OpenFlow Switching
1.
A way to run experiments in the networks we use
everyday.
A “pragmatic” compromise
Allow researchers to run experiments in their network…
…without requiring vendors to expose internal workings.
Basics
An Ethernet switch (e.g. 128-ports of 1GE)
An open protocol to remotely add/remove flow entries
The Stanford Clean Slate Program
http://cleanslate.stanford.edu
The Ossified Network
Routing, management, mobility management,
access control, VPNs, …
Feature
Feature
Million of lines
of source code
5400 RFCs Barrier to entry
Operating
System
Specialized Packet
Forwarding
Hardware
Billions of gates Bloated
Power Hungry
Many complex functions baked into the infrastructure
OSPF, BGP, multicast, differentiated services,
Traffic Engineering, NAT, firewalls, MPLS, redundant layers, …
An industry with a “mainframe-mentality”, reluctant to change
3
Ethernet Switch
4
Control Path (Software)
Data Path (Hardware)
5
OpenFlow Controller
OpenFlow Protocol (SSL/TCP)
Control Path
OpenFlow
Data Path (Hardware)
6
Flow Table Entry
“Type 0” OpenFlow Switch
Rule
Action
Stats
Packet + byte counters
1.
2.
3.
4.
Switch MAC
Port
src
+ mask
MAC
dst
The Stanford Clean Slate Program
Forward packet to port(s)
Encapsulate and forward to controller
Drop packet
Send to normal processing pipeline
Eth
type
VLAN
ID
IP
Src
IP
Dst
IP
Prot
TCP
sport
http://cleanslate.stanford.edu
TCP
dport
OpenFlow Switching
Controller
OpenFlow Switch specification
OpenFlow Switch
sw Secure
Channel
hw
low
F
n
e
Op ocol
t
Pro
SSL
Flow
Table
The Stanford Clean Slate Program
http://cleanslate.stanford.edu
PC
Step 1:
Separate Control from Datapath
Research Experiments
Decision making
is decoupled
Step 2:
Cache flow decisions in datapath
“If header = x, send to port 4”
“If header = y, overwrite header with z, send to ports 5,6”
“If header = ?, send to me”
Flow
Flow
Table
Table
Mininet simulator
●
●
process-based virtualization: many hosts and
switches on a single OS kernel
Network namespaces: lightweight virtualization
feature
●
●
●
individual processes with separate network
interfaces, routing tables, and ARP tables
create kernel or user-space OpenFlow switches,
controllers to control the switches, and hosts
Full access to hosts → xterm, tcpdump
Mininet Architecture
Mininet
●
●
●
●
●
simple and inexpensive network testbed
for OpenFlow apps
Topology aware and OpenFlow-aware CLI
supports custom topologies, and includes
a basic set of parametrized topologies
Works out of the box
provides a Python API for network
creation and experimentation
Sample Mininet custom topology
#!/usr/bin/python
from mininet.net import Mininet
from mininet.topolib import TreeTopo
tree4 = TreeTopo(depth=2,fanout=2)
net = Mininet(topo=tree4)
net.start()
h1, h4
= net.hosts[0], net.hosts[3]
print h1.cmd('ping -c1 %s' % h4.IP())
net.stop()
A small network (4 hosts, 3 switches in Tree topology), and pings one host
from another
Tutorial Setup
Controller
Controller
c0 port6633
port6633
loopback
(127.0.0.1:6633)
OpenFlow Tutorial
3hosts-1switch
topology
s1
OpenFlow
OpenFlowSwitch
Switch
s1-eth0
h1-eth0
h2
h2
10.0.0.2
10.0.0.2
s1-eth1
h3-eth0
h3
h3
10.0.0.3
10.0.0.3
virtual hosts
loopback
(127.0.0.1:6634)
dpctl
dpctl
(user
(userspace
space
process)
process)
s1-eth2
h4-eth0
h4
h4
10.0.0.4
10.0.0.4
15
Tutorial
16
Full set of slides and more info:
●
●
OFELIA tutorial (demo)
Openflow OFELIA tutorial slides(Berlin, Feb
2011)
●
Nick McKeown's SDN slides
●
Openflow intro slides
●
Mininet overview
●
Bob Lantz , Mininet presentation 2009
FlowVisor-based Virtualization
Mariano’s
Controller
Nick's
Controller
Space Invader's
Controller
OpenFlow
Protocol
OpenFlow
Switch
OpenFlow FlowVisor
& Policy Control
OpenFlow
Protocol
OpenFlow
Switch
OpenFlow
Switch
18
OpenFlow building blocks
oftrace
oftrace
oflops
oflops
Monitoring/
debugging tools
openseer
openseer
Stanford Provided
ENVI
ENVI
(GUI)
(GUI)
NOX
NOX
LAVI
LAVI
Beacon
Beacon
FlowViso
r
Console
Commercial Switches
HP,
HP,NEC,
NEC,Pronto,
Pronto,
Juniper..
Juniper..and
andmany
many
more
more
n-Casting
n-Casting
Helios
Helios
Expedient
Expedient
Applications
SNAC
SNAC
Controller
Maestro
Maestro
Slicing
Software
FlowVisor
FlowVisor
Stanford Provided
Software
Software
Ref.
Ref.Switch
Switch
NetFPGA
NetFPGA
Broadcom
Broadcom
Ref.
Ref.Switch
Switch
OpenWRT
OpenWRT
PCEngine
PCEngine
WiFi
WiFiAP
AP
OpenVSwitch
OpenVSwitch
OpenFlow
Switches
19