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Improving SD-WAN Resilience: From Vertical Handoff to WAN-Aware MPTCP

Enterprises are investing more and more in SD-WAN solutions as legacy dedicated WAN connections incur relatively high costs and are cumbersome to operate. One of the key challenges to SD-WAN adoption is lack of resilience with the ability to provide and maintain an acceptable level of service in the face of challenges to normal operation.


Jean Tourrilhes, a principal engineer in the Networking and Distributed Systems Lab of Hewlett Packard Labs, has been focused on SD-WAN and how Labs is helping to address SD-WAN’s resilience challenges. His long-awaited paper, co-authored with Puneet Sharma, about leveraging Multipath-TCP was published in March and gives us an idea of where improving SD-WAN resilience is headed.

We caught up with Jean to get his thoughts on the current and future state of SD-WAN.


What is SD-WAN and why is it important?
SD stands for software-defined and WAN stands for wide area networking and is basically any network connectivity outside a building. SD-WAN is a new way for companies to deploy WAN between their different offices. Instead of using dedicated links provided by telecommunication companies, it uses commodity Internet links and a layer of software-defined networking (SDN) management. SD-WAN is important because it makes WAN connectivity cheaper, and WAN connectivity is needed more and more because of the demands of the cloud and IoT.


What are some SD-WAN adoption and technical challenges?
Networking is always difficult and complicated, and it's always challenging with delays from all the different use cases and deployment scenarios. In the case of SD-WAN, the main challenge is that the commodity Internet links do not provide any of the performance and features that enterprises are used to with dedicated WAN links, so there is a lot of work in the SDN layer to provide an enterprise-class solution. One of them is resilience, as the commodity Internet links may suffer various kinds of outages.


How does HPE address the resilience challenge with its solutions?
At a high level, resilience is always solved by multipathing, which means deploying multiple paths between locations. At HPE, we have products that implement our own solutions that are mostly fallback like main path and backup path. Our solutions, such as Silver Peak, offer better performance than traditional solutions, both in terms of having applications aggregate the bandwidth of multiple links, but also making the impact of outages imperceptible.


What is your paper about?
Labs’ recently published paper presents research the team has done about using Multipath-TCP to provide resilience for SD-WAN deployments. Multipath-TCP is a new standard developed by IETF, the Internet standard organization. We’ve created mechanisms enabling Multipath-TCP to use the multiple links available at the SDN gateway, and further implemented mechanisms to improve the performance of Multipath-TCP to recover from outages. In particular, our paper extended the WAN-awareness from gateway to end hosts. This WAN awareness allows Multi-TCP to be used natively at end nodes that improves scalability and faster recovery from outages.


Dr. Joon-Myung Kang, the Guest Editor of the Special Issue on Advanced Management of Softwarized Networks is excited about the paper. “The major highlight of the work is to provide a strong impact for reliable wide-area data transfer between the cloud and edge locations using the MPTCP method.  WAN-aware MPTCP (WaMPTCP) is a simple yet effective idea that keeps the benefits of MPTCP even with a single physical NIC situation with consideration of WAN side network.”, says Dr. Kang. According to him reviewers liked the strong evaluation demonstrating the good performance gain of the WaMPTCP on both emulated testbeds as well as real-world deployment.


Title: Improving SD-WAN Resilience: From Vertical Handoff to WAN-Aware MPTCP

Authors:  Yang Zhang, Jean Tourrilhes, Zhi-Li Zhang, Puneet Sharma  

Journal: IEEE Transactions on Network and Service Management, Special Issue on Advanced Management of Softwarized Networks


About Jean Tourrilhes
Jean Tourrilhes has worked on many networking projects at Hewlett Packard Labs and has participated in various standardization and open source projects. His most notable contributions are in the areas of wireless LANs, Linux, OpenFlow, and SDN. Recently, he has been working on SD-WAN with projects on Multipath-TCP and bandwidth estimation.

About Puneet Sharma
Puneet Sharma is Director of Networking and Distributed Systems Lab and a Distinguished Technologist at Hewlett Packard Labs where he leads research on Edge-to-Cloud Infrastructure for 5G, IoT and AI. He is a Fellow of IEEE and Distinguished Scientist of ACM.s

About the Author


Managing Editor, Hewlett Packard Labs