1. Mobile Communication and Internet Technologies
Software Defined Networks and OpenFlow
Mobile Communication and Internet Technologies
Courtesy of:
AT&T Tech Talks

2. Module Overview
Motivation
What is OpenFlow
Deployments
Conclusion

3. Specialized Packet Forwarding Hardware
We have lost our way
Routing, management, mobility management, access control, VPNs, …
App
App
App
Million of lines of source code
5400 RFCs
Barrier to entry
Operating
System
Specialized Packet Forwarding Hardware
500M gates
10Gbytes RAM
Bloated
Power Hungry

4. An industry with a “mainframe-mentality”
iBGP, eBGP
IPSec
Authentication, Security, Access Control
Multi layer multi region
Software
Control
Router
Hardware
Datapath
Firewall
L3 VPN
anycast
IPV6
NAT
multicast
Mobile IP
HELLO
OSPF-TE
HELLO
L2 VPN
RSVP-TE
VLAN
MPLS
HELLO
Many complex functions packed into the infrastructure
OSPF, BGP, multicast, differentiated services, Traffic Engineering, NAT, firewalls, MPLS, redundant layers, …
An industry with a “mainframe-mentality”

5. Process of innovation made worse by captive standards process
Deployment
Idea
Standardize
Wait 10 years
Driven by vendors
Consumers largely locked out
Layer by layer innovation

6. New Generation Providers already Buying into It
In a nutshell
Driven by cost and control
Started in data centers….
What New Generation Providers have been Doing Within the Datacenters
Buy bare metal switches/routers
Write their own control/management applications on a common platform 6 6

7. Change is happening in non-traditional markets
Network Operating System
App
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
Specialized Packet Forwarding Hardware
App
Operating
System
Specialized Packet Forwarding Hardware

8. The “Software-defined Network”
2. At least one good operating system
Extensible, possibly open-source
3. Well-defined open API
App
App
App
Network Operating System
1. Open interface to hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware

9. Trend Virtualization or “Slicing” Virtualization layer
Controller 1
App
Controller 2
Virtualization or “Slicing”
OpenFlow
NOX
(Network OS)
Network OS
App
App
App
Windows
(OS)
Linux
Mac OS
Windows
(OS)
Linux
Mac OS
Windows
(OS)
Linux
Mac OS
Virtualization layer
x86
(Computer)
Computer Industry
Network Industry
Simple common stable hardware substrate below+ programmability + strong isolation model + competition above = Result : faster innovation 9

10. What is OpenFlow?

11. Short Story: OpenFlow is an API
Control how packets are forwarded
Implementable on COTS hardware
Make deployed networks programmable
not just configurable
Makes innovation easier
Result:
Increased control: custom forwarding
Reduced cost: API  increased competition

12. Ethernet Switch/Router

13. Control Path (Software)
Data Path (Hardware)

14. OpenFlow Controller Control Path OpenFlow Data Path (Hardware)
OpenFlow Protocol (SSL/TCP)
Control Path
OpenFlow
Data Path (Hardware)

15. OpenFlow Firmware Controller PC OpenFlow Flow Table Abstraction
Software
Layer
Flow Table
MAC
src
dst IP
Src
Dst
TCP
sport
dport
Action
Hardware
Layer *
port 1
port 1
port 2
port 3
port 4

16. OpenFlow Basics Flow Table Entries
Rule
Action
Stats
Packet + byte counters
Forward packet to port(s)
Encapsulate and forward to controller
Drop packet
Send to normal processing pipeline
Modify Fields
Now I’ll describe the API that tries to meet these goals.
Switch
Port
VLAN ID
MAC
src
MAC
dst
Eth
type IP
Src IP
Dst IP
Prot
TCP
sport
TCP
dport
+ mask what fields to match 16

17. Examples Switching Flow Switching Firewall Switch Port MAC src dst Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action * *
00:1f:.. * * * * * * *
port6
Flow Switching
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action
port3
00:20..
00:1f..
0800
vlan1 4
17264 80
port6
Firewall
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Forward * * * * * * * * * 22
drop

18. Examples Routing VLAN Switching Switch Port MAC src dst Eth type VLANID IP
Src
Dst
Prot
TCP
sport
dport
Action * * * * * * * * *
port6
VLAN Switching
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action
port6,
port7,
port9 * *
00:1f.. *
vlan1 * * * * *

19. OpenFlow Usage Dedicated OpenFlow Network
Controller
Aaron’s code PC
OpenFlow
Switch
OpenFlow
Protocol
Rule
Action
Statistics
OpenFlow
Switch
OpenFlow
Switch
Rule
Action
Statistics
Rule
Action
Statistics
OpenFlowSwitch.org 19 19

20. Network Design Decisions
Forwarding logic (of course)
Centralized vs. distributed control
Fine vs. coarse grained rules
Reactive vs. Proactive rule creation
Likely more: open research area

21. Centralized vs Distributed Control
Centralized Control
Distributed Control
Controller
Controller
OpenFlow
Switch
OpenFlow
Switch
Controller
OpenFlow
Switch
OpenFlow
Switch
Controller
OpenFlow
Switch
OpenFlow
Switch

22. Flow Routing vs. Aggregation Both models are possible with OpenFlow
Flow-Based
Every flow is individually set up by controller
Exact-match flow entries
Flow table contains one entry per flow
Good for fine grain control, e.g. campus networks
Aggregated
One flow entry covers large groups of flows
Wildcard flow entries
Flow table contains one entry per category of flows
Good for large number of flows, e.g. backbone

23. Reactive vs. Proactive Both models are possible with OpenFlow
First packet of flow triggers controller to insert flow entries
Efficient use of flow table
Every flow incurs small additional flow setup time
If control connection lost, switch has limited utility
Proactive
Controller pre-populates flow table in switch
Zero additional flow setup time
Loss of control connection does not disrupt traffic
Essentially requires aggregated (wildcard) rules

24. OpenFlow Application: Network Slicing
Divide the production network into logical slices
each slice/service controls its own packet forwarding
users pick which slice controls their traffic: opt-in
existing production services run in their own slice
e.g., Spanning tree, OSPF/BGP
Enforce strong isolation between slices
actions in one slice do not affect another
        
Allows the (logical) testbed to mirror the production network
real hardware, performance, topologies, scale, users
Prototype implementation: FlowVisor
very text heavy; think about a picture (what!?)
"systems solution to a networking problem (this is why it's at OSDI)"

25. Add a Slicing Layer Between Planes
Slice 2
Controller
Slice 3
Controller
Slice 1
Controller
Slice
Policies
"Each slice runs its own, custom control plane process and generates its own rules"
Control/Data
Protocol
Rules
Excepts
Data
Plane

26. Network Slicing Architecture
A network slice is a collection of sliced switches/routers
Data plane is unmodified
Packets forwarded with no performance penalty
Slicing with existing ASIC
Transparent slicing layer
each slice believes it owns the data path
enforces isolation between slices
i.e., rewrites, drops rules to adhere to slice police
forwards exceptions to correct slice(s)

27. Slicing Policies The policy specifies resource limits for each slice:
Link bandwidth
Maximum number of forwarding rules
Topology
Fraction of switch/router CPU
FlowSpace: which packets does the slice control?

28. FlowSpace: Maps Packets to Slices
"flowspace is a way of thinking about classes of packets"
"each slice has forwarding control of a specific set of packets, as specified by packet header fields"
"that is, all packets in a given flow are controlled by the same slice"
"each flow is controlled by exactly one slice" (ignoring monitoring slices for the purpose of the talk)
"in practice, flow spaces are described using ordered ACL-like rules"

29. Real User Traffic: Opt-In
Allow users to Opt-In to services in real-time
Users can delegate control of individual flows to Slices
Add new FlowSpace to each slice's policy
Example:
"Slice 1 will handle my HTTP traffic"
"Slice 2 will handle my VoIP traffic"
"Slice 3 will handle everything else"
Creates incentives for building high-quality services

30. FlowVisor Implemented on OpenFlow
Server
Servers
Custom
Control
Plane
Switch/
Router
OpenFlow
Firmware
Data Path
Controller
FlowVisor
OpenFlow
Controller
Network
OpenFlow
Protocol
Stub
Control
Plane
OpenFlow
Firmware
Data
Plane
Data Path
Switch/
Router
Switch/
Router

31. FlowVisor Message Handling
OpenFlow
Firmware
Data Path
Alice
Controller
Bob
Cathy
FlowVisor
Rule
Policy Check:
Is this rule allowed?
Policy Check:
Who controls this packet?
Full Line Rate
Forwarding
Exception
Packet
Packet

32. OpenFlow Deployments

33. OpenFlow has been prototyped on….
Ethernet switches
HP, Cisco, NEC, Quanta, + more underway
IP routers
Cisco, Juniper, NEC
Switching chips
Broadcom, Marvell
Transport switches
Ciena, Fujitsu
WiFi APs and WiMAX Basestations
Most (all?) hardware switches now based on Open vSwitch…

34. Deployment: Stanford Our real, production network 15 switches, 35 APs
25+ users
1+ year of use
Same physical network hosts 7 different Stanford demos

35. Deployments: GENI

36. (Public) Industry Interest
Google has been a main proponent of new OpenFlow 1.1 WAN features
ECMP, MPLS-label matching
MPLS LDP-OpenFlow speaking router: NANOG50
NEC has announced commercial products
Initially for datacenters, talking to providers
Ericsson
“MPLS Openflow and the Split Router Architecture: A Research Approach“ at MPLS2010

37. Conclusions Current networks are complicated OpenFlow is an API
Interesting apps include network slicing
OpenFlow has potential for Service Providers
Custom control for Traffic Engineering
Combined Packet/Circuit switched networks

38. Q A
&

39. Assignment #6
Write Notes on the terms highlighted in Red in slides 36 and 37
Write a summary of the paper “MPLS Openflow and the Split Router Architecture: A Research Approach“ at MPLS2010