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How SDN applications will change Layer 4-7 network services

With SDN apps, engineers can deploy virtual appliances for Layer 4-7 network services that will be automated for more granular traffic management.

While much of the attention around the impact of software-defined networking has been on the potential commoditization...

of Layer 2/3 Ethernet switching and routing hardware, SDN will also have a major impact on Layer 4-7 network services.

What are Layer 4-7 network services?

Layer 4-7 services optimize and secure the network and depend on a diverse group of elements, including load balancers, WAN optimization appliances, firewalls, SSL VPNs and Intrusion Detection and Prevention (IDS/IPS).

In aggregate, the Layer 4-7 networking market represents approximately $10 billion in end-user spending worldwide. Most of this spending goes toward network hardware appliances that are integrated with software and tightly tied to the underlying network to reduce latency, drive highly scalable performance and ensure reliability.

How SDN applications will change Layer 4-7 services

SDN can change Layer 4-7 network services by enabling virtual applications of load balancing, WAN acceleration and network security appliances. These virtual appliances use the information gathered by SDN controllers and provide a holistic view of the physical and virtual network. Virtual Layer 4-7 appliances then use this information along with granular programmability of flows on the network to enable application-specific services in the context of an overall SDN architecture.

When it comes to security, for example, SDN can use this information for traffic engineering to direct flows to specific firewalls or IDS/IPS elements, thus helping to align the right security application with the right traffic flow. In addition, separating the logical from the physical aspect of the network allows Layer 4-7 attributes to follow the application as virtual machines migrate to new physical locations.

Using SDN applications for Layer 4-7 network services can also result in savings. Traditional hardware-based Layer 4-7 elements can be quite expensive, while SDN technologies often offer the same functionality for lower CAPEX. Meanwhile SDN can improve automation of Layer 4-7 network services for a lower OPEX.

A number of SDN startups are already adopting SDN technologies to bring about better Layer 4-7 services. These companies include Embrane, ADARA, Big Switch, LineRate (now part of F5), Anuta Networks, Pluribus Networks and V-Armour Networks.

SDN for Layer 4-7 is not quite ready for prime time

The challenge in applying SDN to Layer 4-7 networking is that this segment of the market represents a diverse set of highly specialized applications that are difficult to consolidate and centralize. What's more, specialized hardware is often required to deliver high performance Layer 4-7 services.

In the near term, SDN Layer 4-7 capabilities are likely to be used by medium-sized enterprise customers. But, in the long run, SDN has the potential to significantly impact traditional Layer 4-7 appliances by offering more flexible, easy-to-manage and less expensive software-based functionality. The current leaders in Layer 4-7 will need to enhance their product offerings with SDN technologies to continue to be successful in this market.

About the author:
Lee Doyle is principal analyst at Doyle Research. Doyle Research provides targeted analysis on the Evolution of Intelligent Networks: SDN, OPEX and COTS. Lee Doyle has over 28 years of experience analyzing the IT, network and telecom markets. For more information please see, email me at and follow me on Twitter @leedoyle_dc.

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This was last published in April 2013

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