software-defined networking(sdn):a new approach to networking
TRANSCRIPT
SOFTWARE-DEFINED NETWORKING(SDN)
A New Approach to Networking
Anju Ann JosephSemester: VII Batch: C
B-Tech Seminar Sept 2013
2
Seminar OverviewIntroduction
Why we need new approach?
Why not traditional networks?
SDN Architecture
OpenFlow Approach
Virtual Network Overlay Approach
Challenges & Future Expectation
Conclusion
3
Introduction
Software Defined Networking (SDN) is an evolutionary approach to network design and functionality based on the ability to programmatically modify the behavior of network devices.
SDN uses user-customizable and configurable software that’s independent of hardware to expand data flow control.
It will make networks more flexible, dynamic, and cost-efficient, while greatly simplifying operational complexity.
4
The Need for a New Network Architecture
Changing Traffic Pattern
The Rise of Cloud Services
Consumerization of IT
“Big data” means more bandwidth
Perc
enta
ge o
f net
wor
k tr
affic
Control plane: Routing algorithms
5 Management plane:
Configure basic activities
Data Forwarding plane:
Packet streaming
Traditional Computer NetworksData flow is controlled by switches and routers and contains the following basic elements:
Traditional Networks worked well…
6
Hardware based networks have historically shown that they were stable and reliable.
Operational capacities were quickly regained after a power loss, without significant external interventions.
Operated consistently in varying environments.
But..
7
1
2
Limitations of Current Networking Technologies
Complexity that leads to Static Nature
Inconsistent Policies
Inability to Scale
Vendor Dependence
3
4
So we need something NEW!
Introducing Software-Defined Networking
8
Software Defined Networking (SDN) is an emerging network architecture where network control plane is decoupled from
forwarding plane and is directly programmable.
Lead by Open Networking Foundation(ONF)
SDN-enabled control plane allows the underlying infrastructure to be abstracted
Network appears to the applications as a single, logical switch entity
SDN Architecture
OpenFlow Switches
9
SDN Control Software
Business Appl Business Appl Business Appl
Northbound API
Southbound API(eg. OpenFlow)
INFRASTRUCTURELAYER
CONTROL LAYER
APPLICATIONLAYER
10
APISpecifies how software components should interact each other.
API’s makes it possible to implement basic network functions like path computation, loop avoidance, routing, security and many other tasks.
Southbound API
Northbound API
Allows controller to define the behaviour of switches at the bottom of the architecture
Provides a network abstraction interface to the applications and management systems at the top of the architecture
SDN Controller
11
The controller is the core of an SDN network.
By running the control plane as software, the controller facilitates automated network management and makes it easier to integrate and administer applications.
SDN controllers uses protocols such as OpenFlow to configure network devices
It manages flow control to enable intelligent networking.
12
OpenFlow is a protocol that is used to define the communication interface between the control and forwarding layers.
It provides direct access to and manipulation of the forwarding plane of network devices.
Uses the concept of flows to identify network traffic.
Approach
13
OpenFlow-enabled Switch
Controller
Secure Channel
Group Table
Flow Table
Flow Table
OpenFlow protocol
OpenFlow switch
Components:Flow table & Group tablePerform packet lookups and forwarding
OpenFlow channelInterface that connects a switch to a controller
Two types
OpenFlow-hybrid
OpenFlow-only
Pipeline
Pipeline process: Maintains sending of packets between flow tables by matching flow entries.
14
OpenFlow PortsLogically connects each OpenFlow switch
Types of ports: standard logical reserved
OpenFlow Packet header
Version Type Length of Msg Transaction id
0 7 15 31 63
MAC src
MAC dst
IP src IP dst VLAN ID
Src port
Dst port
…. Action Count
Flow Table
15
Inside OpenFlow
Packet arrives at switch
Header fields compared to flow table entries
Forwarded to specified port
DroppedOREncapsulates packets and sends to controller
Controller decides
Drops Make new entry in flow table
OR
Match FoundMatch Not Found
16
Message Types
Controller-to-switch messages• Modify-state• Read-state• Packet-out/in• Barrier• Role-Request
Asynchronous messages• Packet-in• Flow-removed• Port-status
Symmetric messages• Hello message • Echo request/reply
Benefits of OpenFlow Approach
17
Centralized Control
Reduced Complexity through Automation
Higher rate of Innovation
Increased Network Reliability and Security
Use Case: Network Slicing among large Data Centers
18
Large Data centers have to accommodate many access requests, each seeking a unique policy and security requirements.
SDN helps to overcome this by creating logical isolated networks and allow them to be partitioned using slicing technique.
Involves abstraction of control plane management, out of each network device into a centralized controller via OpenFlow protocol, helps isolated networks to grow within themselves and also communicate with other networks.
19
Few vendors who have produced OpenFlow enabled network switches
Few OpenFlow based SDN Controllers
Programmed in C++/Python on Linux framework
Java based controllerFocuses on achieving better performance using multithreading
MX series IBM Rack Switch
20
Virtual Network Overlays(VNO) Approach
It creates a virtual network infrastructure for the underlying physical network.
Using VNO concept, the physical network is partitioned into multiple logical networks that can be individually programmed and managed.
21
VNOs are based on a ‘map-and-encap’ approach:
1. Mapping performed to find the destination address of the packet
2. Overlay device encapsulates the packet within an overlay header
3. Encapsulated packet is forwarded to destination where it is de-encapsulated
Scheme followed by VNO- Tunneling SchemeEx:VXLAN(Virtual Extensible LAN)
22
VXLAN(Virtual Extensible LAN)
It is a tunneling scheme to overlay Layer2 networks on Layer3.
Virtual LANs (VLAN) have similar functioning, but its specifications only allow for up to 4,096 network IDs to be assigned at any given time.
Extends the VLAN address space by adding a 24-bit segment ID (VNI)and increasing the number of available IDs to 16 million.
VNI can differentiate individual logical networks so millions of isolated Layer 2 networks can co-exist on a common Layer 3 infrastructure.
With VLANs, only virtual machines (VMs) within the same logical network can communicate with each other. VXLAN can potentially allow network engineers to migrate VMs across long distances.
Use Case: Multi-tenancy in Cloud Computing Environment
23
In a cloud environment, abstraction of the management layer becomes important to enable more interaction of applications with the networking elements.
The virtual network overlay abstracts the underlying physical network, which allows the overlay to move to other physical networks.
Virtual Network Overlay stack for Cloud
OpenStack
OpenStack Plug-in
Rest API
Virtual Network Switch
Hypervisor
Tenant 1 Tenant 2 Tenant 3
VXLAN
Challenge
24
To support co-existence with existing devices the existing technologies must have additional enhancement.For ex, the existing standard path computation elements in routers are not sufficient, they need to be enhanced.
Future ExpectationTo find a unique SDN approach.
Some Frequently Raised Questions..
25
Why is SDN taking so long to adopt?• Enterprises confused about how SDN will specifically
save them on network costs• No compelling use-cases
Is SDN and network virtualization same?• similar goals• overlapping sets of technologies
Conclusion
26
SDN promises to transform today’s static networks into flexible ,scalable, programmable platforms with the intelligence to allocate resources dynamically.
With its many advantages and astonishing industry momentum, SDN is on the way to become- the new approach for networking.
References
27
[1]:Kapil Bakshi,“Considerations for Software Defined Networking(SDN):Approaches and Use Cases,” IEEE Aerospace Conference, March 2013.
[2]:“Software-Defined Networking: The New Norm for Networks,” Open Networking Foundation(ONF) White Paper, April 2012.
[3]:“Software Defined Networking: A new paradigm for virtual, dynamic, flexible networking,” IBM Systems and Technology Thought Leadership White Paper, October 2012.
[4]: Hyojoon Kim and Nick Feamster, “Improving network management using SDN,” IEEE Communications Magazine, February 2013, pp.114-119.
28
Got any Questions?
29