length: 01:00:00

Mohammad Al Khalidi, Juniper ASCE

SDN is a concept by which the data and control plane are decoupled on a network level. The control plane functions are carried by a network controller, which controls the whole network devices. Hence, by programming the  centralized controller, you "program" the network behavior.

The idea came from application developers that would like to slice out a part of the network for testing new ideas and protocols, where any new protocol can be designed/tested and implemented on a life network, without affecting the network operations.


application layer: serves
control layer: controller
network layer: switches
host/data layer: clients


2 elements of SDN:
1. network controller
2. network switches.

a vendor can develop only network controller or only network switches or develop both controller & switches.


Main difference:
1. no protocol run between the network devices
2. when network switch receive packet for the first time, it buffers and consult the controller by sending the packet header
3. controller check the header, and based on the info, decides which rule to put & how to forward traffic
4. controller opens path for the data stream across the network


Advantages:
1. better network utilization & faster convergence
2. controller has more processing power
3. faster feature deployment
4. no need of routing protocol
5. mobility of the devices

Disadvantages:
1. latency
2. redundancy of controller - single point of failure(?)
3. complexity of controller


Openflow is the protocol that runs between the controller and the network devices. It is currently maintained by the Open Network Foundation.

Makes use of flow tables inside routers and switches, and allows the controller to manipulate these tables based on the network requirements.

Need of standardized protocol & vendor interoperability

Based on a match condition on the variables in the packet header (up to layer 4) -> filter based forwarding.

Openflow is not necessary the only protocol for controller/device communication for SDN networks. It is practically the only protocol being discussed in this field.

Current version: 1.3

Google is pretty happy with the SDN experiment, question arise such how the

SDN in practice:

wifi mobility was one of the first application was developed with the concept of SDN.


Load balancing:


benefit, controller knows where the clients and where the serves - hence it allows optimization of the traffic.
it really can optimize & make the best use of the links.



3. Application Driven Network.
the application can drive the controller decisions - it allow the servers to talk to controller and in turn the controller redirect the traffic
very mature: having the application to talk to the network.




Conclusion:

SDN started as concept to run testing programmable network along side the traditional network
SDN proved to be very appealing in many application - demands is up
interoperability between all vendor, cost reduction,

Labels: cissp, cpe7, webinar