Opportunities and Research Challenges of Hybrid Software Defined Networks ACM SIGCOMM Computer Communication Review table of contents archive Volume 44 Issue 2, April 2014 Authors: Stefano Vissicchio and Olivier Bonaventure from Université catholique de Louvain, Louvain-la-Neuve, BelgiumLaurent Vanbever from Princeton University, Princeton, NJ, USA

Outline Why use hybrid SDN (hSDN)? Type of hSDNs Tradeoff analysis Topology based hSDN (TB hSDN) Service based hSDN (SB hSDN) Class based hSDN ( CB hSDN) Integrated hSDN Tradeoff analysis Conclusion Future work Reference

Why use hybrid SDN (hSDN)? SDN has a lot of advantages. Simplify management Spur innovation Improve network flexibility However… Full SDN require huge number of initial deployment costs. Operator need to dismiss expensive commercial off-the-shelf network (CN) device to enable full SDN deployment. Training cost. Production-level SDN controller still seem hard to realize. They need: Security policy enforcement High availability Lowest possible delay

Why use hybrid SDNs (hSDN)? – cont’d However… The full SDN architecture may lack Reliability Robustness Scalability Hybrid SDN If we need centralized control and we also want scalability in our network, why do not we use hybrid SDN? If we do not have enough money to upgrade all device to support SDN, why do not we use hybrid SDN?

Topology based hSDN (TB hSDN) The network is partitioned in disjoint zones. In SDN (resp. CN ) zones, all services are provided by SDN (resp. CN). Transition strategy: CN manage the back-bone traffic SDN control non-critical traffic Why? It eases the introduction of new mechanisms to exchange information between SDN zones and CN zone. Forwarding Information Base (FIB) of SDN FIB of CN Physical link

Service based hSDNs (SB hSDNs) CN and SDN provide different service. Transition strategy: SDN progressively handles more and more services. Why? Operators may be willing to keep existed CN protocols instead of relying on new software to be integrated in the SDN controllers. SDN is used for services that CN solutions cannot satisfactorily provide. SDN provide edge-to edge tunneling and wide area network forwarding is delegated to CN Forwarding Information Base (FIB) of SDN FIB of CN Physical link

Class based hSDNs ( CB hSDNs) All node can be controlled by CN and SDN. All node provide all network service. Transition strategy: All node must support both CN and SDN protocols. This model may be adopted as a long-term design. Why? CN can work as a backup when SDN control plane crashes. Forwarding Information Base (FIB) of SDN FIB of CN Physical link

Integrated hSDNs SDN is responsible for all network services, and uses CN protocols as an interface to devices’ FIBs. Transition strategy: Step1: Move the control plane from CN to SDN Step2: Adding SDN devices and updating the SDN controller. Why? SDN is easy to offloaded when SDN is die. Forwarding Information Base (FIB) of SDN FIB of CN Physical link

Tradeoff analysis TB: Controller與CN control plane之間需要合作，讓cross-zone的service能夠正常地運作 SB: Data plane 需要協調好， CB: 如果要將CN的Traffic移到SDN traffic 會有困難 I:

Conclusion and future works. Explore the hSDN models. Some challenges of hSDN: The cross-paradigm techniques need to be studied. A control plane redesign would be needed to allow effective cooperation between SDN controllers and CN controllers. The added complexity of combined heterogeneous networks may hamper the development of SDN in a hSDN. Personal opinions: It provides some useful reference for me. My implementation belongs to SB hSDNs. I can use its example to convince others that my system is useful. Their design suggestions can be better. Personal opinions: It provides some useful reference for me. My implementation belongs to SB hSDNs. So what…?

Reference Software-Defined Networking (SDN) Definition [https://www.opennetworking.org/sdn-resources/sdn- definition]