Flipping the Switch: A Mixed vs. Hybrid Approach to SDN Deployments

In a recent blog, we described some of the different approaches companies are taking to make the transition to software-defined networking (SDN). The unfortunate fact of the matter is that – unless there are extra resources / money lying around – it is very unlikely that any company will flip the switch from a traditional network to a software-defined one overnight. Instead, most companies will employ either a mixed or a hybrid approach. There are a host of reasons why companies might choose one approach over the other, and there are benefits and drawbacks to each of these approaches.

Mixing it up

A mixed approach requires companies to replace portions of their network with SDN equipment. For example, although Google has largely left their consumer-facing network unchanged, they’ve implemented SDN equipment in the connections between their data centers. They are concurrently running both an SDN network and a traditional network.

This approach allows companies to take advantage of the new technology, which is easier to manage, configure and deploy, without disturbing their existing network. The technology can effectively be tested without impacting revenue or day-to-day business needs. It can also help identify problems early on in the SDN deployment process so that issues can be corrected before they escalate.

One of the big downsides to this is the cost. Because an entire portion of the network is being switched over to SDN all at once, the equipment must all be replaced together, which can be quite costly. This can delay the completion of the change to a completely software-defined network. Companies may be more reluctant to replace the legacy portions of the network because the costs are bundled together, rather than spaced out. Additionally, IT staff and network administrators must either be trained or hired so that the SDN infrastructure can be appropriately managed alongside the existing network.

A mixed network should be approached with caution. Oftentimes, the legacy and SDN portions of the network have difficulty communicating with each other, so the deployment must be planned carefully in order to avoid problems. This can be a costly method as well, with large amounts of money spent at one time, making it a more difficult method for smaller companies to utilize.

Hybrid

A hybrid approach requires a box-by-box transition from legacy networks to SDN, for example, OpenFlow™. Utilizing hybrid switches and routers, a hybrid network can communicate with both legacy equipment and OpenFlow-based equipment, in the same way that a bilingual person can speak both English and Spanish.

Utilizing a hybrid approach can spread out the costs, allowing equipment to be replaced as it fails or as budgets permit, rather than replacing entire chunks of the network at one time. Because the costs are spread out, they can be easier to justify, which can actually speed the deployment of a full software-defined network over time. As more SDN-compatible equipment enters the network, tests can be run to identify possible problems. SDN can even be deployed in portions of the network to begin experiencing the benefits of the technology, without impacting performance on the rest of the network since the two technologies can talk to each other.

However, taking this approach can cause the network to become more complex, which can make troubleshooting difficult. Just as with a mixed approach, IT staff and network administrators must be able to work with both systems, adding costs in the form of training or new staff. It can also be a more difficult approach to get off the ground, since the costs begin accumulating for a period of time before the technology is implemented and the benefits experienced.

A hybrid approach is often more palatable to the mid-size companies that don’t have Google-levels of money to spend, but are looking to capitalize on the benefits of SDN technology. Though it can create complexity within the network, it also eliminates or reduces many of the problems associated with the mixed network approach. For most companies, it is a more ideal approach, reducing the upfront costs while still providing all the benefits of SDN. Many network equipment vendors are also offering SDN functions such OpenFlow compliance as an add-on to traditional networking functions.

We are an active member of the Open Network Foundation, working to drive the OpenFlow protocol. The company’s hardware and software offerings, which include QorIQ LS2 family and VortiQa SDN software solutions, provide a variety of options to OEM / ODM companies looking to build SDN designs.