Topics for ODL Design Summit from HP contains the following proposal, making the case for integrated hybrid OpenFlow:
We would like to share our experiences with Customer SDN deployments that require OpenFlow hybrid mode. Why it matters, implementation considerations, and how to achieve better support for it in ODLThe Open Networking Foundation (ONF), the body behind the OpenFlow standard, released Outcomes of the Hybrid Working Group in March 2013, concluding:
OpenFlow-compliant switches come in two types: OpenFlow-only, and OpenFlow-hybrid. OpenFlow-only switches support only OpenFlow operation, in those switches all packets are processed by the OpenFlow pipeline, and cannot be processed otherwise. OpenFlow-hybrid switches support both OpenFlow operation and normal Ethernet switching operation, i.e. traditional L2 Ethernet switching, VLAN isolation, L3 routing (IPv4 routing, IPv6 routing...), ACL and QoS processing
The rationale for supporting hybrid mode is twofold:
- Controlled switches have decades of embedded traditional networking logic. The controller does not add value to a solution if it replicates traditional forwarding logic. One alternative controller responsibility is that provides forwarding decisions when it wants to override the traditional data-plane forwarding decision.
- Controllers can be gradually incorporated into a traditional network. The common approach to enterprise SDN assumes a 100% pure SDN-controlled solution from the ground-up. This approach is expensive in terms of actual cost of new switches and in terms of downtime of the network. By providing a controller that can gradually migrate to an SDN solution, the hybrid approach enables customers to start seeing the value of having an SDN controller without requiring them to make a huge leap in replacing their existing network.
On the whole, the group determined that industry can address many of the issues related to the hybrid switch. ONF does not plan or intend to incorporate details of legacy protocols in OpenFlow. The priority of ONF in this context is to explore the migration of networks to OpenFlow.OpenDaylight has broad industry participation and should be a good forum to discuss integrated hybrid OpenFlow use cases, enhance open source controller support, and address multi-vendor interoperability. HP should find support for integrated hybrid OpenFlow among Open Daylight members:
- Brocade - Brocade has been shipping products supporting hybrid OpenFlow for over a year, see The Practical Path to SDN: Brocade OpenFlow Hybrid Port Mode. Brocade won the 2014 ONS SDN Idol competition with a solution for DDoS mitigation that combined their hybrid OpenFlow switches with the Open Daylight controller and InMon's real-time sFlow analytics software to address the challenge of mitigating large DDoS flood attacks - see ONS2014 SDN Idol finalist demonstrations
- Red Hat - Red Hat's Brent Salisbury is an OpenDaylight software developer and advocate for hybrid OpenFlow, see Hybrid OpenFlow Using The Normal Action
- Juniper - advocated for integrated hybrid OpenFlow at the 2012 ONF Summit, see Hybrid Programmable Forwarding Plane
Integrated hybrid OpenFlow is a practical method for rapidly creating and deploying compelling SDN solutions at scale in production networks. It's encouraging to see HP engaging the Open Daylight community to deliver solutions based on hybrid OpenFlow - hopefully their proposal will find the broad support it deserves and accelerate market adoption of hybrid OpenFlow based SDN.
Update October 8, 2014: Slides from the summit are available, OpenFlow-hybrid Mode