0. Kandoo: A Framework for Efficient and Scalable Offloading of Control Applications
Author : Soheil Hassas Yeganeh, Yashar Ganjali
Publisher : Hotsdn 2012
Presenter : Pei-Hua Huang
Date : 2013/10/16

1. INTRODUCTION
Frequent and resource-exhaustive events, such as flow arrivals and network-wide statistics collection events, stress the control plane and consequently limit the scalability of OpenFlow networks
To limit the load on the controller, frequent events should be handled in the closest vicinity of datapaths, preferably without modifying switches
讓SDN scalable須限制frequent event 在control plane的overhead
現法是移到data plane做但要modify switch
應在datapath附近不改switch

2. INTRODUCTION
How can we move control functionalities toward datapaths, without introducing new datapath mechanisms in switches?
environments where processing power is readily available close to switches or can be easily added
applications that are local in scope
如何做到不改switch
環境 processing power離switch近 data center network
或是容易加新的enterprise network
Applilication是local,event在單一switch做不需用network-wide state

3. INTRODUCTION Kandoo two-level hierarchy for controllers
local controllers : execute local applications
root controller : run non-local control applications
local controllers can linearly scale with the number of switches in a network
completely compliant with the OpenFlow specifications
gives network operators the freedom to configure the deployment model of control plane functionalities based on the characteristics of control applications

4. INTRODUCTION

5. DESIGN AND IMPLEMENTATION
Design objectives
Goals
must be compatible with OpenFlow
automatically distributes control applications without any manual intervention

6. DESIGN AND IMPLEMENTATION

7. DESIGN AND IMPLEMENTATION
Kandoo Controller
有多個local 一個root
組成kandoo control plane

8. DESIGN AND IMPLEMENTATION
Deployment Model
The deployment model of Kandoo controllers depends on the characteristics of a network
provision the number of local controllers based on the workload and available processing resources

9. DESIGN AND IMPLEMENTATION

10. DESIGN AND IMPLEMENTATION
Control Applications
Control applications function using the abstraction provided by the controller and are not aware of Kandoo internals
Control applications are loaded in local name spaces and can communicate using only Kandoo events
local controller can run an application only if the application is local

11. DESIGN AND IMPLEMENTATION
Event Propagation
The root controller can subscribe to specific events in the local controllers using a simple messaging channel plus a filtering component
Reactive vs. Proactive
pushing network state proactively

12. DESIGN AND IMPLEMENTATION
Implementation Details
in a mixture of C, C++, and Python
provide an RPC API
extremely modular
support OpenFlow 1.0
create a " central application repository" and a simple package management system
Single-node Performance
A single Kandoo controller can reach a throughput of more than 1M pkt-in per second from 512 switches using a single thread on a Xeon E7-4807

13. EVALUATION
Setup
Physical server equipped with 64G of RAM and 4 Intel Xeon(R) E CPUs
use OpenVSwitch 1.4 as kernel-level software switch

14. EVALUATION

15. EVALUATION Methodology
measure the number of requests processed by each controller and their bandwidth consumption
the number of elephant flows in the network
(use a tree topology of depth 2 and fanout 6)
the number of nodes in the network
(fix ratio of the elephant flows at 20%)

18. RELATED WORK Datapath Extensions
DIFANE tries to partly offload forwarding decisions from the controller to special switches, called authority switches
DevoFlow introduces new mechanisms in switches to dispatch far fewer " important" events to the control plane

19. RELATED WORK Distributed Controllers
HyperFlow [18], Onix [8], SiBF [10], and Devolved Controllers [17] try to distribute the control plane while maintaining logically centralized, eventually consistent network state
Middleboxes
Flow-Stream [7], SideCar [15] and CoMb [13], provide scalable programmability in data plane by intercepting flows using processing nodes in which network applications are deployed
希望control plane 可logically 集中physically distributed
方法都有好處但有各自的限制
都假設所有app都需要network wide state
去處理app deploy的node來做截流
在data plane上提供 scalable

20. RELATED WORK Active Networks
Ans allow programmability in networking elements at packet transport granularity by running code encapsulated in the packet or installed on the switches
Kandoo differs from active networks in two ways
Do not provide in-bound packet processing
not an all-or-nothing solution

21. CONCLUSION Kandoo is a highly configurable and scalable control plane
Kandoo local controllers do not propagate an OpenFlow event unless the root controller subscribes to that event