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

Yang Zhang, Jean Tourrilhes, Zhi Li Zhang, Puneet Sharma

Research output: Contribution to journalArticlepeer-review


Demands for wide-area connectivity between enterprise site-edge networks and central office core networks/cloud data centers have grown rapidly. Various software defined wide area network (SD-WAN) solutions have been developed with the primary aim of improving WAN link utilization. However, mechanisms used by existing SD-WAN solutions fail to provide high reliability and performance required by today's edge to cloud applications. In this article, we present WAN-aware MPTCP which seamlessly aggregates multiple WAN links into a 'big pipe' for better WAN resilience thus minimizing application performance degradation under WAN link failures. We leverage the congestion control of MPTCP to balance traffic across multiple WAN links. The key innovation is to combine LAN virtualization at end systems with WAN virtualization at SD-WAN gateways. Through evaluation in both emulated testbeds and real-world deployment, we demonstrate the performance gain of WAN-aware MPTCP in terms of resilience and throughput over existing SD-WAN solutions.

Original languageEnglish (US)
Article number9328552
Pages (from-to)347-361
Number of pages15
JournalIEEE Transactions on Network and Service Management
Issue number1
StatePublished - Mar 2021

Bibliographical note

Funding Information:
Manuscript received June 2, 2020; revised October 24, 2020, December 24, 2020, and January 8, 2021; accepted January 13, 2021. Date of publication January 19, 2021; date of current version March 11, 2021. This work was supported in part by DoD ARO MURI under Award W911NF-12-1-0385; in part by DTRA under Grant HDTRA1-09-1-0050; and in part by NSF under Grant Grant CNS-1411636, Grant CNS-1618339, Grant CNS-1617729, Grant CNS 1814322, and Grant CNS183677. The associate editor coordinating the review of this article and approving it for publication was J. M. Kang. (Corresponding author: Yang Zhang.) Yang Zhang and Zhi-Li Zhang are with the Department of Computer Science, University of Minnesota–Twin Cities, Minneapolis, MN 55455 USA (e-mail:

Funding Information:
Gateway Routing: Routing on the SDN gateway forwards packets originated in a subnet to the associated WAN link. This relies on source-specific routing which is supported by most OSs. Only subnet-based static rules are required for routing instead of generating a rule for each flow. Return packets coming from WAN links are routed based on destination subnet (classical routing). Our routing technique is implemented to support both VxLAN tunneling to a remote gateway and direct routing to the Internet. The number of rules in both directions only depends on the number of subnets, independently of the number of clients. If the subnets are optimally allocated, subnet routing requires only a number of rules equal to the number of WAN links. This very low number of rules offers great scalability and avoids control plane churn.

Publisher Copyright:
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  • Software defined networks
  • edge networks
  • wide area networks


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